Turning the wasted area in your attic into a habitable room (or two) is one of the best ways to add space and value – but there are some loft conversion mistakes that could ruin all your efforts.

While many common errors can be avoided if you thoroughly research how to plan a loft conversion, it is also useful to be aware of the mistakes most frequently made by homeowners in order to ensure you don't follow in their footsteps.

To help you out, I reached out to the experts to ask which mistakes they most commonly see people making and for advice on how to carry out a loft conversion that is nothing but a success.

1. Underestimating the need for head height

The number one mistake all the experts I spoke to listed was a failure to look into how much head height is required for people's loft conversion ideas to become a reality.

'A loft conversion is a major project, and even small mistakes can lead to costly delays or problems down the line,' picks up Rob Wood, MD of Simply Loft. 'Lofts need a minimum of 2.2 metres headroom (measured from floor to ridge beam) to meet building regulations comfortably. Always measure before committing.'

'One of the biggest issues is not checking the head height properly before starting,' agrees home improvement expert Myles Robinson. 'Just because the loft looks roomy doesn't mean it's suitable for conversion. Always get a proper survey done early to avoid design headaches down the line.'

2. Assuming planning permission won't be needed

While planning permission for loft conversions is often not needed, you should never take this as a given.

'Although many loft conversions don’t need planning permission, some in conservation areas or to listed buildings will,' explains Tina Patel, RIBA-chartered architect and director at Architect Your Home. 'In conservation areas, there are strict guidelines on the sizes of any dormer extensions and even the type of rooflights to use and you will almost always need permission for any external changes.

'You should always check if you benefit from permitted development for lofts as it is not just homes in conservation areas that don’t have these rights. We have seen instances from the 1960s where permitted development rights have been removed from the entire estate,' continues Tina.

'Where you do have rights, you need to be careful to ensure the requirements are carefully followed; there are requirements in terms of volume that can be added at loft level, limitations on height relative to the existing roof, materials that can't be used and set backs on dormer extensions – if not followed this would be a breach of your permitted development rights and the council could take enforcement action.

It is always worth getting a Certificate of Lawfulness from the council – this is important not just to be sure that the proposal meets the requirements but useful if you ever need to sell the house.'

3. Ignoring loft conversion building regs

Just because your loft falls within permitted development, you will still need to adhere to loft conversion building regulations.

'Even if planning isn’t needed, building regulations approval definitely is,' says Myles Robinson. 'Skipping this step or going with a builder who doesn’t stick to the rules can lead to problems when you try to sell.'

The building regs surrounding loft conversions cover all kinds of things, but an area of particular confusion seems to be fire safety.

'A common mistake we see in lofts is poor understanding of fire regulations,' picks up Tina Patel. 'With an extra storey you will want to ensure you and your family are protected in the unfortunate event of a fire.

'There are requirements within dormers for these to be fire rated so as to stop the spread of fire to neighbouring properties (again, something often overlooked as it can be a bit more expensive to get this right). Use of a non-combustible board, such as Supalux, on the dormer walls can prevent the spread of fire to neighbouring properties. The doors to all habitable rooms at loft level will need to be fire rated and you may also need to consider changing doors to the lower levels in the house too.'

4. Poor staircase planning

All too often, homeowners focus solely on the design and construction of the new loft conversion without fully thinking through how it they will actually access it – so think through your loft conversion stairs carefully.

'A bad staircase layout can waste space or ruin the flow of your home,' warns Rob Wood. 'Get expert advice early to avoid awkward placements.'

'A badly positioned staircase can eat into the floor below and disrupt your existing layout,' further explains Myles Robinson. 'We often see conversions where the stairs have been added as an afterthought, rather than integrated into the design from the start. Ideally, stairs should rise above your existing staircase, so you're not cutting into valuable bedroom or hallway space.'

5. Skipping structural checks

This is, potentially, a very serious mistake that could not only mean your loft conversion costs will soar, but also that you risk the safety of your home's occupants.

'It is common for people to try to save costs on structural checks hoping that the existing building will handle the extra load,' says Farook Member, director and home design expert at QS Supplies. 'Always have a structural engineer check the joists. The floor may have to be reinforced to meet building regulations and avoid sagging.'

If you are using a reputable loft conversion specialist or builder with experience of loft conversions, they should carry out all of these checks and advise you before any structural work gets underway.

6. Misjudging good bathroom design

Depending on what you plan on using your newly converted loft for, you may well want to include some attic bathroom ideas, or a shower room, up there. This needs to be carefully planned in if you want to ensure it benefits rather than negatively impacts your existing spaces.

'Often adding a loft means needing an additional bathroom – if you only have one existing bathroom and a combi boiler it is highly likely that this will not be able to support an extra bathroom with hot water requirements and heating,' explains Tina Patel.

'What is the point of having two bathrooms if they cannot be used at the same time? This is something that is often overlooked and early infrastructure considerations can avoid this – you may need to factor in a boiler upgrade and even increase of the incoming water supply pipe to your home if the pressure is insufficient in order to avoid issues with trickling water from your shower.'

Tina has some further advice for those considering using a macerator for their new loft conversion bathroom.

'Unless done well, the use of sanitary macerators in loft bathrooms can be problematic – these are used for drainage of soil waste and involve the waste being crushed so it can flow through a smaller pipe,' explains Tina. 'The big issue is that they can be noisy so you end up with your desired en-suite but then because they are so noisy you can't use the bathroom as intended! This can be avoided by considering the drainage route from the outset so that it can be picked up through the main system in a concealed way.'

7. Failing to budget properly

This is a really big one – unless you go into your loft conversion project fully aware of how much it is going to cost you, there is a risk that you'll run out of funds midway through.

While the average loft conversion costs between £50,000 and £90,000, it is possible for them to end up coming in at more than this, particularly if you need to lower the ceilings in the rooms below.

It is also worth noting that there are some often-overlooked costs to factor in, including insulation, good lighting, flooring, electrics and, of course, final decoration.

8. Trying to squeeze too much in

It is all too easy, in the excitement of planning the perfect loft space, to expect too much from your newly converted attic room.

‘’A big mistake is trying to squeeze in too much,' agrees Myles Robinson. 'It’s easy to get carried away thinking about extra bedrooms or a bathroom up there, but the space has to work comfortably.

'Poor layout planning can leave you with awkward corners, unusable eaves, or rooms that just feel tight and out of proportion. The best loft conversions make smart use of light and storage, fitted wardrobes into the eaves or clever built-ins. These can make all the difference.'

9. Overlooking the need for adequate insulation

Just as with garage conversions, lofts were usually not constructed with day-to-day habitation in mind. What this means is that they will need upgrading in order to feel comfortable to spend time in.

'Ventilation and insulation are often overlooked,' points out Myles Robinson. 'Lofts tend to get warm in summer and cold in winter, so getting your insulation right, not just to meet regulations but to make the space actually comfortable, is essential.

'Without proper ventilation, especially in a loft bathroom, you’ll end up with condensation issues and potentially mould,' continues Myles. 'Make sure extractor fans are vented properly to the outside and not just into the roof space.'

10. Forgetting the importance of good storage

Great storage forms a key part of any successful room scheme, so failing to build in enough is a huge mistake.

'Often, we see people try to make the room feel bigger by bringing the eaves space into the room,' begins Tina Patel. 'Although this may, in theory, sound like it will increase the footprint, as you get closer to the lower part of the pitch at the front of the property this space is difficult to stand in and so not useable and impossible to clean well. It is far better to have well designed storage in this space to allow you to manage the head room and retain some storage for things that used to be in the attic such as Christmas tree decorations and suitcases.

'It is also a great place to store the boiler and hot water cylinder if you have nowhere else to locate them – if height is limited, you can use a horizontal one.'

FAQs

Do I need a structural engineer for a loft conversion?

Just as when building an extension, structural engineers are frequently brought into loft conversion projects, particularly during the building regulations stage when they will calculate the weight of your proposed structure, and specify key elements needed for support and so on.

While using a structural engineer is highly recommended, there is not a legal requirement, and in some cases your chosen loft conversion specialist will be able to carry out the calculations needed. That said, a structural engineer really can come in handy when it comes to applying for building regs approval, even submitting forms on your behalf.

A loft conversion won't be for everybody. If you are still unsure, take a closer look at all the extension ideas available before making your final decision.

Transforming the space in your attic into a useable room is one of the best ways to gain extra space without extending your house, but it can be hard to choose between the different types of loft conversion in order to select the best one for your home and needs.

Everything from the age of your property to your budget, the size of space you need to what you want to use it for should play a part in the kind of conversion you opt for.

There are five main options available to most people considering loft conversion ideas: rooflight; dormer; hip-to-gable; mansard and modular. Here, with the help of the experts, we'll take a look at each, explaining how they are constructed, their pros and cons as well as how much they're likely to cost.

Rooflight loft conversions

Before, or at the very least at the same time as, you look fully into how to plan a loft conversion, you need to understand the decisions you will be faced with. If you are worried about loft conversion costs, you'll be happy to learn that this is the simplest and cheapest type of loft conversion. It is also sometimes referred to as a Velux loft conversion.

'If you want your loft conversion to be simple yet effective then a skylight or Velux conversion may be best,' explains Rob Wood, MD of Simply Loft. 'The structure of your roof isn’t changed in any way – windows are simply added. It’s ideal for creating a spare bedroom or an office space, although does not maximise your space internally so it’s not the best option if you want to create a couple of additional rooms.'

'With this type of loft conversion you often do not need planning permission,' adds Ian Garner, project coordinator at Absolute Lofts. 'What’s more, because there are no large alterations made to the roof, it is likely to help keep the cost of the conversion down.'

Average cost: From £50,000

Pros of rooflight conversions

• Cheapest
• Least disruptive
• Usually classed as Permitted Development
• Relatively quick to complete

Cons of rooflight loft conversions

• Limited headroom
• Not suitable for all types of loft, such as trussed

Dormer loft conversions

This is another incredibly popular and widely-seen type of loft conversion, suitable for most roof constructions. If you are wondering if you need planning permission for a loft conversion then this is a style that usually falls under permitted development.

'This is the most popular type of loft conversion we work on and usually doesn’t require planning permission (although it’s always worth checking this),' says Rob Wood. 'It can provide up to 50 cubic metres of additional space and lots of head height.'

'A dormer loft conversion involves installing a box shaped structure into the pitched roof (sloped roof) of your home,' picks up Ian Garner. 'The right-angles of the dormer create a flat rather than sloped roof, giving you ample headroom and classic room shape dimensions. As the main windows face directly outwards, a dormer lets in lots of natural light and offers great views of the outside.'

There is actually not just one type of dormer loft conversion, making it a versatile option too.

• Flat roof dormer: These are a common type of dormer with, as the name suggests, a flat roof. They typically sit to the rear of a house and extend the full width of the building.
• Side dormer: These are added to the side of a sloping roof. 'They are ideal for adding space to a property where the roof ridge runs from the front to the back of the home,' says Ian Garner.  
• Front pitched dormer: These are small dormers with pitched, rather than flat, roofs.
• L-shaped dormer: These involve two dormers that are connected to create an L-shape – perfect for creating bigger spaces.

Average cost: From £55,000

Pros of dormer loft conversions

• Leaves you will a full-height space
• Allows for the use of standard, vertical windows
• Makes it possible to fit patio doors and balconies
• Lots of design flexibility
• Often won't require planning permission

Cons of a dormer loft conversion

• More expensive than rooflight conversions
• May not feel as light as conversions lit by rooflights, depending on the angle of the roofline

Hip-to-gable loft conversions

Hip-to-gable loft conversions are suitable for most types of properties with a hipped roof – one that has all its sides sloping equally downwards from the top to the vertical walls.

'The loft space is constructed by turning one of the sides of the hip roof into a gable roof, creating a triangular-shaped, vertical end wall,' explains Ian Garner. 'The new gabled section of roof creates additional height and floor space for the new loft room.'

'You can even add a dormer to this, combining the two conversion types for an extra large space,' adds Rob Wood.

You can sometimes create this type of loft conversion using Permitted Development but you'll need to check with your local planning office.

Average cost: From £60,000

Pros of hip-to-gable loft conversions

• Perfect for creating large new spaces
• Lots of headroom
• Adds considerable value to a property

Cons of hip-to-gable loft conversions

• More structural work needed
• Not suitable for terraced homes
• Expensive
• May require planning permission

Mansard loft conversions

If your extension ideas require you to get the very most space from your loft conversion, this is the option for you.

'If you’re seeking to super-size your loft space, a mansard loft conversion is the largest loft renovation you can choose,' says Ian Garner.

'A mansard conversion is typically built to the rear of your property and has a horizontal roof with an almost vertical 72-degree back wall,' continues Ian. 'Windows are usually housed within a box-shaped dormer which project slightly, enhancing internal space even further and allowing natural light to flood in.'

A double mansard is another option, whereby a mansard is added to both the front and rear of the house, essentially creating a whole new storey.

Average cost: From £69,000.

Pros of mansard loft conversions

• Add almost a whole new storey to a house
• Suitable for all kinds of house, including terraced
• Allow in lots of natural light

Cons of a mansard loft conversion

• Most expensive
• Usually needs full planning permission

Modular loft conversions

Right up there at the top of the price scale, but also one of the best ways to get tonnes of extra space, lie modular loft conversions.

In reality, no conversion really takes place. Rather, the entire roof of the house is lifted away to be replaced with a prefabricated structure, complete with walls (exterior and interior), floor and new roof. Often, these structures can also be specified with radiators, lights, sockets and switches, radiators and even stairs if you wish. Plasterboarding and skimming will also often be included.

Although this all sounds terribly disruptive when compared to building an extension, as most of the work is carried out off-site, ready to be craned into place, it actually makes the whole thing simple and very speedy. As everything is agreed upfront, the chance of any hidden costs is reduced too.

Average cost: From £53,000

Pros of modular loft conversions

• Fixed price agreed upfront
• Speedy build times
• Adds lots of value to a house
• Suitable for all kinds of roof constructions
• Considerable space added (a whole new storey, in fact)

Cons of modular loft conversions

• Expensive
• Require planning permission
• Access needed for cranes and delivery lorries
• Less design flexibility than some other types

FAQs

What's the cheapest type of loft conversion?

If you were hoping to keep a lid on your extension costs and want to convert your loft on a budget, the best option will be a rooflight (aka skylight or Velux) loft conversion.

'This is one of the simplest and most cost effective loft conversions to build as the roof of the property is not altered in any way and only windows are added,' explains Rob Wood.

If you are after more ways of adding space to your home without extending, there are loads of garage conversion ideas worth checking out too.

If you're planning on turning your loft into living space, then one of the first hurdles is how you will get to it – in short, where will your loft conversion staircase go and how do you design a flight that meets all the regulations?

When planning a loft conversion, you not only need to think about the type of roof construction you're dealing with and whether or not planning permission will be granted for what you're hoping to achieve, but also the feasibility of your project.

If you can't access your newly converted space from the storeys below, the whole thing will be a write off – which is where our guide to loft conversion stairs comes in. We asked the experts everything, from the best way to position them to how to overcome any obstacles you might encounter.

What are the rules for loft conversion stairs?

Before you even begin to think about staircase ideas for your loft access, it is vital that you make yourself aware of the building regulations surrounding this all-important aspect.

Rob Wood, MD of Simply Loft shares the key points to be aware of:

• Loft stairs must have minimum headroom of 2m (can be reduced slightly in limited spaces)
• Have a maximum pitch of 42 degrees

Architect Tina Patel from Architect Your Home has some further useful information on loft conversion building regulations for homeowners considering converting their loft.

'The building regulations that cover stairs also outline requirements for handrails, although you can be creative around how these are dealt with,' she begins. 'Although there is no minimum width requirement, we would recommend 90cm wide to be able to comfortably get furniture up – although if limited, you can go for a little less.

'There are also considerations for depth and height for each step – consistency is key here and no step can be taller than 220mm in a domestic setting.'

Finally, fire regulations will need to be observed if you want your loft conversion to meet current standards.

'An important consideration is that of fire, and how someone can escape from the top floor,' explains Tina Patel. 'In most instances (unless you are installing a domestic sprinkler system) where the staircase leads all the way to ground exit level, you will need to have a protected hallway. This can impact doors in hallways too and these should be clear of the top and bottom of stairs. If this will eat up too much space, you can think about the use of sliding doors to help.'

Where's the best place to put your loft conversion stairs?

Once you understand the building regulations concerning your loft staircase, you should have clearer idea of the most practical place for it within your loft conversion ideas as a whole.

'Ideally your new stairs will go above the existing staircase below to save space and maintain flow,' picks up Rob Wood. 'If that’s not possible, consider placing them off the landing or within a larger room, for example the main bedroom – but be mindful of your layout.'

'Where you put stairs often depends on a number of parameters,' picks up Tina Patel. 'The starting point would be the layout at first floor level and how much of this you are willing to change, as well as what type of space you want to create in the new loft. For example, if you want two rooms, often a stair through the middle can be a clever way of getting space for storage at the first floor level and maximising rooms in the loft.'

'Whether or not you are adding extra volumetric space at loft level, either by undertaking a hip-to-gable extension or adding a dormer will also have a role to play,' continues Tina.

'If you are in a terrace, the positioning will depend on whether you are extending out to the section to the rear known as an 'outrigger' as well as the main roof – often these two spaces in old Victorian homes in particular can be at different levels so this will impact how a staircase can be positioned as you may need access at both levels.'

Does a loft conversion mean sacrificing a bedroom?

Depending on the layout of your first floor, it may well make sense to use either an entire bedroom or at least part of a larger room, to accommodate the new staircase. In many semi-detached and terrace properties, it makes sense to use some small box room ideas for your new stairs.

'Typically, your staircase will go over the one coming up from the ground floor, and in many instances, you may need to pinch some space from one of the first floor rooms to allow for this,' explains Tina Patel.

'This will ensure that you get clear headroom at both levels – clear headroom, under the regulations, means you need to have 2m minimum clearance in a vertical line from each step to the structure above. This can be tight if you do not have a lot of height in the existing loft although there are workarounds, such as using better performing insulation and lowering ceilings at first floor level,' continues Tina. 'It is also worth remembering that you don't need 2m clearance in rooms, only to staircases.

'Normally, we would advise that to comfortably accommodate a staircase, the attic space, before any conversion, from the existing structure in the roof floor to the pitched roof structure should be over 2.4m – this will allow for insulation and increasing the floor thickness, which will most likely be needed since most existing attics are not designed to take the loads needed to become living spaces.'

What space-saving options are there?

If you are really struggling to find space for a standard staircase, when it comes to buying a staircase, bear in mind that there are space-saving staircases to consider.

'If space is very tight, you can consider an alternating stair,' explains Tina Patel. 'These can be real space savers, albeit not great where children may be using the steps as you use one step per foot to get up.'

Another option to consider where space is really limited is a spiral staircase. Providing they adhere to building regs requirements, they can be ideal where floor space is pinched.

What is the best type of staircase for loft conversions?

This really does depend on your layout and the design of your home but, in an ideal world, your loft stairs would match your principle staircase, as well as your hallway ideas.

'We make sure that every new staircase matches the same design, look and feel to the existing staircases,' picks up Ian Garner, project coordinator at Absolute Lofts. 'We’ll even use an existing spindle as a pattern guide to ensure a bespoke finish. This is also the case with the newel posts and handrails, meaning consistent looking staircases throughout that look as though they’ve always been there.'

Rob Wood has some more tips on loft stair design. 'Use turns or spirals to save space and consider adding storage underneath in the form of drawers and cupboards,' he says. This can help if you are worried about where to store the things that were previously stored in your loft.

'Keep the finish light and open to avoid cramping the area too,' adds Rob.

'Generally, in terms of design, think about how you can get natural light all the way down through the stair, either by a tall window or skylight at the top,' suggests Tina Patel. 'If you can, be creative with storage on the landing too.'

FAQs

How will you get furniture to your loft conversion?

Something many homeowners overlook when planning the perfect loft space is how they will get their furniture into their newly converted loft – big mistake.

There are several different approaches to consider when getting bulkier items of furniture, such as beds, bathtubs and sofas, into a loft conversion.

Perhaps the simplest is to opt for pieces that are supplied flat-packed, ready to be put together in-situ. At the very least, choosing modular furniture that can be broken down into sections should make life easier. You could also consider having custom made storage, such as built-in wardrobes and drawers, that will be constructed within the loft.

If you have fallen in love with a bed or sofa that just can't be taken up the stairs into your new loft space, however, many companies out there have furniture lifts and hoists that make it possible to take large items in through loft windows.

In any case, inform the delivery company of the spatial restrictions so that they know what to expect in advance.

Remember, when budgeting for your loft conversion costs, to include your staircase, as well as any additional costs you might incur by using a delivery company to hoist large furniture into the new space.

Loft conversions are a hugely popular way to add both space and value to all kinds of properties, offering many benefits over other kinds of extensions. That said, while they often won't require you to get formal planning consent, you will still need to familiarise yourself with loft conversion building regulations if you don't want to run into any issues.

Many homeowners looking into how to plan a loft conversion feel confused by the world of building regulations – and it isn't hard to see why. There is so much terminology to get to grips with and 'Approved Documents' to look into.

Fear not, though, our guide is here to demystify building regulations for loft conversions and ensure that your new addition runs without a hitch from start to finish.

What are the building regulations for a loft conversion?

If you are still a little unsure of what the building regulations are, let us explain. They are basically a set of standards, made up of Approved Documents, each of which relates to a different element of a property, from its structure to how energy efficient it is. They were put in place in order to ensure that homes are both safe to live in as well as comfortable. They are constantly changing and being added to and these days focus very much on energy efficiency. Whether you are building an extension or converting your loft, these regs will apply.

'Anyone contemplating a loft conversion must ensure that they comply with building and planning regulations,' explains MD of Simply Loft Rob Wood. 'Building regulations will cover structural safety, fire safety, insulation and ventilation, and escape routes.'

Which Approved Documents relate to loft conversions?

Although this list isn't exhaustive, in general, the Approved Documents you should familiarise yourself with when developing your loft conversions ideas are:

• Approved Document A: Structural safety
• Approved Document B: Fire safety
• Approved Document L: Energy efficiency
• Approved Document K: Protection from falling
• Approved document P: Electrical safety

Building regs for structural safety

Approved Document A lays out all the standards that must be met in relation to the structural safety of your loft conversion.

When looking at how to create the perfect loft space, it is often discovered that the roof and floor structures need to be modified. In this case, a structural engineer will usually be brought in do do the necessarily calculations to submit to Building Control.

'The drawings and calculations engineers do are submitted to Building Control,' explains architect Graham Ford of Graham Ford Architects. 'Once the design has been approved and correctly installed then Part A of the building regulations can be approved. This sign off is one of the key parts of gaining your completion certificate, along with thermal design, fire design and all other aspects of the building regulations.'

How do you satisfy fire safety regulations?

Meeting the fire safety section of the building regulations is hugely important and a large part of this means understanding fire door regulations.

All loft conversions are required to have a protected escape route leading from the loft to the exit on the ground floor. The route should offer protection from fire for at least 30 minutes. Additionally, loft staircases must offer 30 minutes of fire resistance. They will need to be checked to ensure they comply with building regs.

When it comes to the matter of fire doors, most doors used within a loft conversion will need to be fire doors and fire resistant to 20 minutes.

What building regs relate to loft staircases?

Whatever your new staircase ideas leading to your loft conversion look like, they will need to meet the standards set out in Approved Document K.

Stairs should have a minimum headroom of 2m with a pitch no greater than 42°. In addition, they must not be any less than 800mm wide and their handrails should sit 900mm-1000mm above the pitch line.

Finally, the gaps between any spindles in the balustrades must be no larger than 99mm.

Could building regulations mean I can't convert my loft?

One very important section of the building regulations surrounding loft conversions relates to headroom and, in certain cases, where they can't be met, a loft conversion can be very tricky (or expensive).

'There is a minimum requirement of 2.0m at the top stem of the loft stairs (reduced to 1.9m in the centre of the step if it is under a sloping ceiling), and in addition, many homeowners will want to maximise the finished height to give a feeling of spaciousness,' explains Rob Wood.

The good news is that if you don't currently have the headroom in your existing loft space, there are ways of increasing it – although this may push up your loft conversion costs.

'Whatever the reason(s) for increasing the height in the loft, there are potentially two ways that this can be achieved,' picks up Rob Wood. 'In properties that have a very tall ceiling on the level below the loft, it may be possible to lower the ceilings on that level to effectively increase the height in the loft. This can be intrusive on the household and typically means redecorating multiple rooms. It may also mean having to vacate the home for a period during construction.

'A more popular approach is to raise the roof to gain the extra loft height needed,' continues Rob. 'This will almost certainly need planning permission as it usually falls outside of permitted development rights. Detached properties are more likely to be granted consent than semi-detached or terraced properties. If only small increases in height (5-10cm) are needed this can often be achieved with minimal extra work and cost, but if larger gains in height are to be achieved this may require substantial extra works and potentially replacing the whole roof structure.'

How can you ensure your loft conversion meets building regs?

In most cases, homeowners will use either an architect or loft conversion specialist to oversee their project, in which case they should be able to advise on complying with the regs. In many cases, they will also be able to submit your plans to Building Control.

However, if you have decided to project manage your own extension or loft conversion, the job will fall to you. You can either use the local authority building control service or a private registered building control approver.

Inspectors will visit at set stages during the conversion to ensure it complies with the regs before signing it off and issuing a completion certificate.

If your builder is registered with a competent persons scheme, they might be able to self-certify some or all the work.

What kind of application do I need to submit?

There are two ways to approach obtaining building regulations approval: a Building Notice or a Full Plans Application.

A Building Notice is usually sufficient for smaller projects such as a loft conversion or small extension ideas. Either you or your builder will give notice to your local authority building control that you are starting a loft conversion and provide simple details of the work that will be carried out. Once this has been done, you can begin and inspections will be carried out as the project progresses. While this is a simpler and quicker route, it can sometimes mean having to go back and alter certain aspects that the inspector might not be happy with.

A Full Plans Application is best for larger or more complex loft conversions. In this case, full architectural drawings, specifications and other relevant documents will be submitted before any work begins. While more arduous, this approach means everything is pre-approved.

What happens if you don't get building regulations approval?

If you fail to inform Building Control of your plans and plough ahead without, you risk being asked to go back and change work which could be costly and very disruptive. In addition, it could make it almost impossible when it comes to sell your house in the future.

FAQs

What other approvals will be needed to convert a loft?

In addition to building regs approval, there are other approvals that might be required.

Although planning permission for loft conversions is not always needed, don't assume anything. Although in many cases loft conversions fall under Permitted Development, there are cases where it won't apply, such as in Conservation Areas or where you are working on a listed building.

It is also worth noting that some types of loft conversion, such as those which have significantly altered the existing roof construction, will not fall under permitted development. Your architect, builder or loft conversion specialist will be able to advise you here.

If you live in a semi-detached or terraced house and your loft conversion will affect a shared wall you need do comply with the Party Wall Act. This can help if you are worried your neighbour will stop you from converting your loft.

And, finally, if you don't own the freehold of your house, additional permissions will be needed.

Still undecided on the best way to add space to your house? Take a look at our advice on extension vs loft conversion to help you choose.

EDITOR’S NOTE: An earlier version of this article included a quote from a purported expert whose credentials we have not been able to verify. The quote has been removed. We regret this lapse in our verification process and have updated our internal protocols to reduce the risk of recurrence.

If you want to ease space pressures in your home, there are a few options available to you, primarily adding more square footage or converting existing space into something more usable. But when weighing up an extension vs a loft conversion, how do you decide on the best route for your home?

Building an extension or planning a loft conversion will both require significant investment, so you'll want to be sure you choose the option that is going to serve you and your property in the most effective way.

To help, we've spoken to the experts to compare how these two projects compare in terms of cost, impact and potential.

Which is right for you — an extension or loft conversion?

If your goal is to increase living space, both an extension and a loft conversion will achieve that, without you needing to move house. But each has their own set of advantages and drawbacks that will need to be carefully considered.

Adding a single-storey extension (or even opting for a two-storey extension) will increase your home's overall square footage, but you'll have to sacrifice some garden space to accommodate it. And it tends to be more expensive to add new space.

On the other hand, a loft conversion makes better use of space you already have, turning an often underused and neglected area into usable living space — leaving your garden unaffected. You can also include dormer windows in your design to maximise the area. However, you'll need to sacrifice some internal space for stairs into the converted loft, even if you opt for a super space-saving staircase, and you might be concerned about what to do with all the stuff you currently have stored in your loft.

You'll also need to factor in the fire door regulations that you will need to meet to adhere to Building Regulations requirements. And, remember, not all roofs are suitable for conversion.

James Ginley, Technical Surveying Director at e.surv Chartered Surveyors, adds: 'When deciding between a loft conversion and an extension, homeowners should consider their property type, existing space, and long-term needs. For a loft conversion, ensure the roof structure allows for enough headroom and that the floor can support additional weight.

'For extensions, consider whether there is sufficient outdoor space and planning permission requirements. Both options should align with your budget, lifestyle, and how you envision using the added space, whether it's for bedrooms, living areas, or home offices, and also which will be more valuable to potential home buyers if you do decide to sell in the future.'

You should also think about what you want to use the additional space for. For example, if you want a bigger kitchen, then a loft conversion won't suit your needs, but if you need an extra bedroom, creating a master suite in the loft could be just the ticket.

Property expert, author of Renovating for Profit and serial renovator Michael Holmes says: 'For families needing additional bedroom space, a loft conversion typically represents the most cost-effective solution - provided your existing roof geometry is suitable - and creates a natural flow with existing upper-floor bedrooms. However, if you're planning an annexe for multi-generational living, a ground-floor extension often proves more practical.

'For those prioritising lifestyle enhancement over essential bedroom space, a ground-floor extension - typically to create a contemporary open-plan kitchen and living space - might be the better first step.'

This also leads on to any permissions you might need when it comes to adding more space. Some changes might class as Permitted Development, whereas others will require you to apply for planning permission instead. Michael adds: 'When faced with the dilemma of choosing between a loft conversion and an extension while budget constraints prevent doing both simultaneously, I always advise homeowners to secure planning permission or prior approval for both projects upfront. This strategic approach locks in your development rights and provides valuable flexibility for the future. The decision on which to tackle first should be driven by your immediate living requirements.'

Is it cheaper to extend or do a loft conversion?

When comparing the cost of loft conversions and extensions, converting your loft tends to work out cheaper, as James Ginley explains: 'Loft conversions are generally cheaper than extensions because they repurpose existing space and typically require less structural work, but this will depend on the type and age of the home.

'While costs can vary depending on specifications and location, a standard loft conversion is often less expensive than building outwards, which involves groundwork, foundations, and potentially higher material and labour costs alongside a likely longer planning permission process.'

Michael breaks down costs further, saying: 'Looking at the financial implications, expect to budget £2,200-£3,300/m² for a single-storey extension, while loft conversions range from £1,500-£2,000/m² for a straightforward rooflight solution to £2,000-£2,800/m² for a dormer conversion. Remember to factor in a 25-35% premium for projects in Greater London and the South East, plus 20% VAT on all costs.'

However, not all loft spaces are suitable for conversion. If there is not enough available headroom in your current loft, then a solution may be to raise the roof, or lower the ceiling below, which will add to the cost. Your existing roof structure may make conversion more complex, depending on where and how the trusses are positioned. Your home's foundations will be a factor too — can they support the additional load? If not, then that is extra expense to be considered too.

And so it may be that the cost of a single storey extension actually works out cheaper, and if you need more space than that, two-storey extension costs could work out more cost-effective than single storey additions.

Which adds more value – an extension or a loft conversion?

Done well, extending your home can increase it's value, as James explains: 'Both options can significantly increase your home's value, but this largely depends on your location and the type of property.' This will likely be more of a concern if you are planning on selling your home down the line. If you are, you'll need to research ceiling property prices in your area so you can see if adding more space is financially viable.

'Loft conversions, especially those that add an extra bedroom and bathroom, can yield a high return on investment in urban areas,' adds James. 'Extensions, on the other hand, can appeal to families looking for larger living areas and often offer more flexibility in design, which may attract buyers. Consulting a property expert or surveyor can help you understand which option aligns better with your market and also current desirable home trends.'

Does an extension or a loft conversion add more space?

If you want to add significant square footage, then an extension might be a better solution, as you're not restricted by the confines of the existing roof, (although the rules around planning permission for an extension may impose some limitations too).

'Extensions can provide greater versatility and more significant space overall, but they involve heavier construction work, which may disrupt your daily life,' says James.

Ultimately, the best choice for your home will depend on your existing home, your budget and how you want to use the additional space. But choose a good architect, who specialises in projects like yours, and they'll help you determine the most suitable option, and one that meets your budget.

If you are looking to expand your home, there are various ways you can do it. But for those looking for additional space upstairs, converting the loft can be particularly ideal. But do you need planning permission for a loft conversion?

Unfortunately, it is not the most straightforward question to answer. If a loft conversion is on your wish list, whether you need planning permission or not will depend on a few different factors. 'The need for planning permission for a loft conversion can vary based on the type of property and its location,' says Rob Wood, managing director at Simply Loft.

If you're set on your loft conversion ideas to add space without extending the footprint of a house (they're usually cheaper to complete than an extension too) then you'll need to understand when you might need planning permission, and when you can move forward without it.

Do I need planning permission for a loft conversion?

This is a complex question to answer, as whether or not you need planning permission to convert your loft will depend on where you live, the specifics of your project and whether your home has undergone significant extensions in the past.

In many cases, you won't need to submit a planning application before you convert a loft. This is because this kind of project is often classed as Permitted Development.

But this isn't a blanket rule, especially if your home is located in a designated zone like a National Park or Area of Outstanding Natural Beauty. So you'll need to check with your local planning authority before you start.

Professional planning consultant Simon Rix, founder of Planix.uk explains: 'To ensure your loft conversion falls under Permitted Development, it’s important to first verify that your home is eligible, taking into account any previous developments or extensions, and whether your home is located in a designated area where such rights don’t apply.'

It can be a huge mistake to just assume your project will fall within your Permitted Development rights because your neighbour didn't have to apply for planning permission for something similar.

'Certain criteria must be met to qualify, such as ensuring the conversion doesn’t exceed specific size limits or alter the roof's highest point,' adds Simon Rix. 'Even if your project meets these criteria, it's advisable to apply for a Lawful Development Certificate from your local council to confirm that planning permission isn't required. This certificate not only provides peace of mind but also serves as a valuable document for future property transactions.'

Can I convert my loft without planning permission?

You won't always need planning permission to covert your loft, as it may be classed as Permitted Development instead. In order for your loft conversion project to fall within the scope of PD, it will need to meet a set of strict criteria:

• Size: If you live in a terraced house, your design should not increase the size of your roof space by more than 40 cubic metres. In other types of houses, this increases to 50 cubic metres.
• Roof height changes: You can't make the existing roof any higher than it is already without planning permission.
• Chimney alterations: Without planning permission you can't add, alter or replace any existing chimneys or flues.
• Window placement: Under permitted development, any new windows to the side of the conversion must be obscured.
• Positioning: Unless you are carrying out a hip to gable loft conversion, your new addition will have to be set back a minimum of 200mm from the eaves. You will also not be allowed to extend the roof more than any existing roof slope that can be seen from the principle elevation.
• Balconies: Balconies, with the exception of Juliet balconies, cannot be constructed under permitted development.

However, if your project should have planning permission and you go ahead without it, then that's a different story.

You could submit a retrospective planning application, but there is no guarantee that permission will be granted. By not having the correct permissions in place, you could face a hefty fine, legal action and even end up having to undo all the work, which could leave you thousands of pounds out of pocket.

When will a loft conversion need planning permission?

If your proposed loft conversion scheme falls outside of the Permitted Development criteria, or you live in a designated area, you will most likely need to apply for planning permission.

'For houses in designated areas, such as conservation areas or those considered listed buildings, additional planning consent is usually required,' explains Rob Wood. 'These areas often have stricter regulations to preserve the character and appearance of the local neighbourhood and community.'

'The design itself must adhere to specific limits regarding the size, materials used and impact on the roof structure,' picks up Simon Rix.

'If your project involves significant alterations, such as with a mansard loft conversion or the addition of a balcony, a full planning application will be necessary. Using a good planning consultant can help navigate these complexities and avoid costly errors, ensuring your project proceeds smoothly.'

'It is important to consult your local authority’s guidelines along with speaking to a professional or an architect about the size and type of your loft conversion,' points out Rob Wood.

FAQs

How do I apply for planning permission for a loft conversion if I need it?

If you find that planning permission is going to be needed for your loft conversion, you can make an application through the Planning Portal or via your local authority's website.

You'll also want to read this tips for securing planning permission first time round to optimise your chances of success (and get you through the process as quickly as possible).

You will need to bear this in mind when budgeting for your loft conversion costs as you can expect fees of around £250 and a service charge of £70.

If you converted your loft without the required consent, you could apply for retrospective planning permission. But this is a huge gamble as there is no guarantee your application will be approved, and you may be required to make changes to, or undo, the work you have done.

Can a neighbour stop my loft conversion?

If you live in a terraced or semi-detached property, might be worried whether your neighbour can stop you from converting your loft.

While they can't stop you from doing the work, provided it meets the criteria of Permitted Development, or that you have the necessary permissions and notifications in place, they can cause delays and stress.

The best way to avoid this is to communicate your plans with your neighbours early on, listen to any concerns they may have, and see if you can reach a mutual agreement that puts their mind at ease without compromising on your plans.

If disagreements arise regarding the party wall, then you may need the help of a party wall surveyor to put them to bed.

Does my loft conversion need building regulations approval?

Regardless of whether your project needs planning permission or not, it will still need to comply with loft conversion building regulations.

'Building regulations cover aspects such as fire safety, structural stability, insulation, ventilation and accessibility,' explains Rob Wood. 'Compliance with these regulations ensures that the loft conversion is safe, energy-efficient, and in line with established building standards.'

If you use an architect or specialist loft conversion company they will help you ensure your project meets all the requirements of building regulations. This could include, for example, adhering to rules around the installation of a new staircase or following fire door regulations.

Do I need a party wall agreement for a loft conversion?

If your loft conversion involves any walls that are shared with another house, you should get a party wall agreement. This is sometimes the case when a conversion requires a new structural beam to be inserted into the shared wall.

'As well as planning permission for your loft conversion, you’ll also have to consider a party wall agreement before work can begin on your project,' advises Rob Wood. 'This is an agreement amongst neighbours if you share a wall or are close in proximity to your neighbouring properties that the construction is accepted by the neighbour.'

You can either serve a Party Wall Notice to your neighbour(s) yourself, or use a Party Wall Surveyor.

Do I need planning permission to board my loft?

If you want to board your loft to use it as storage space, then you won't need planning permission. But if you are worried about the strength of any joists, then it is best to get a professional to assess the space.

Boarding a loft could be tackled by an experienced and competent DIYer, but if you've not done anything like it before, it's definitely best to pay a professional to do it for you.

A loft conversion won't be right for everyone and in some cases building an extension - either single or double storey - is the only way to get the additional space you need.

Even if you decide not to convert your loft into habitable space, you should still make sure it is properly insulated in time for winter.

Are you planning on converting your loft? Let us know in the comments below.

Have you spotted nasty damp in your attic space? Don’t lose sleep over the soggy situation, as we're here to explain how to stop loft insulation once and for all.

Why does condensation form in the attic? Lofts often have little ventilation or heat regulation and so when finding ways to keep your house warm air can become trapped. When the temperature outside our home is cold, and it’s warm downstairs, the clash of conditions leads to water build up on the inside as the trapped air turns to vapour.

'Condensation can be a common issue in lofts due to the temperature difference between the warm air inside your home and the colder air in the loft,' confirms Myles Robinson from CompareBoilerQuotes.co.uk. 'When warm air comes into contact with colder surfaces, such as the roof or walls in your loft, it can cause moisture to condense and form droplets.'

Unless steps are put into place to get rid of loft condensation and prevent it from returning, the nasty dampness can soon lead to expensive structural damage and health-hazardous black mould appearing. Poor roof quality, lack of loft insulation and no air ventilation are the main causes of condensation in the loft. So, fixing these problems will soon prevent loft condensation in the first place.

How to stop loft condensation

Before you can get going with how to stop loft condensation, you'll probably have to get rid of any existing moisture. To dry out existing condensation, first try to regulate the temperature downstairs. Wipe down attic windows, if any, with a window vac that sucks up moisture or paper towels and a clean microfiber cloth. Also open windows for periods of time during the day to flush out dense, damp air. 

The best dehumidifiers are an effective method when removing existing condensation from a loft, or, moisture absorbers, like the UniBond AERO 360, are a budget-friendly alternative.

 'The salts attract moisture from the surroundings, becoming deliquescent and ‘trapping’ the moisture in the dehumidifier,' says Dr Jonathan Kirby, from Dryzone. 'They are ideal for small areas and great at collecting warm moist air to lower condensation.'

1. Fix the roof

As your roof takes the brunt of weather conditions, it is more likely to be affected by temperatures. To prevent condensation from forming in your loft the roof is the first port of call. 

'Check for any signs of leaks or water ingress from the roof or pipes,' advises Myles. 'Water intrusion can worsen condensation issues and also cause other damage. If you notice any leaks, I suggest fixing them promptly to prevent further problems down the line.'

2. Install insulation

Good quality insulation in the loft will keep the space protected. Knowing how to insulate a loft is vital if you want to create a condensation-free zone.

'Proper insulation can help maintain a more consistent temperature in your loft, minimising the risk of condensation,' explains Myles. 'I recommend using insulation materials with a vapour barrier to prevent moisture from reaching the colder surfaces.'

3. Seal any gaps

Don’t forget the loft hatch as this can allow of lot of air to escape through. 

'Check that your loft insulation hasn’t been pushed into the eaves blocking airflow from there and that your loft hatch is correctly sealed to prevent heat loss from the house,' says Rob Stone, founder of Instaloft.

'A great hack for [hatch installation] is to use self-adhesive foam tape - which you can pick up from hardware stores or from Amazon,' adds Tony Adams from Village Heating.

4. Increase air ventilation

Another important step to prevent loft condensation is to ensure that there is a good amount of air circulation in the attic and throughout the rest of your property.

Rob suggests the simplest way to stop condensation in a loft is to install some lap vents. 'These simple vents will add additional circulation of air around the loft and as they are so easy to install you don’t really need a tradesperson to fit them for you. They just slide in between the gaps in your roofing felt meaning no cutting, no screwing and no tools needed.'

Installing windows is an obvious way of increasing ventilation in the loft, so now is the perfect excuse to plan that dream loft conversion.

'This will help to reduce the impacts of condensation. It will additionally bring more natural light into the space and offer the chance to create a multifunctional room,' explains Simon Tcherniak from Neville Johnson.

5. Declutter the loft

An organised space will also aid airflow so avoid using your loft as a crowded dumping ground and add the loft to you list of rooms to declutter. Store items in stackable clear boxes that are clearly labelled so you can see what is in each of them. 

FAQ

When looking to expand an existing home, adding a loft conversion for more space or building an extension on a house are often the most popular solutions. The latter is usually the least intrusive, but a building upwards and converting the loft area will give you so much more space, especially if you have a growing family and you need more bedrooms.

This narrow Victorian two bedroomed property was too small for the family who lived in it - the couple had two children and they needed space for a guest room, too.  They contacted Daniel Rees, founder of Rees Architects to see how they could expand their existing space to accommodate their needs. 

Here, Daniel explains how the team created a considered loft extension to create a balanced family home.

Building loft conversion for more space

‘As a rear extension wouldn’t have helped in gaining extra bedrooms, a loft conversion was the best solution. We needed to use every inch of space purposefully and intentionally,’ explains Daniel of Rees Architects, ‘making the existing plan work hard with thoughtful design was essential. It was also important to create a space that felt warm and generous while being functional'. 

'The ceiling height in the loft area was only two metres high,' continues architect Daniel, 'not considering the space that would be occupied by the structural framework for the planned main dormer and rear dormer over the outrigger.'

'We wanted to solve this in a holistic way, so we lowered the ceilings on the two floors below to achieve more height in the new loft space. By doing so, we have created three floors that feel proportionally aligned rather than one that obviously lacks height.'

Main bedroom

The window seat ideas in the main bedroom have been clad in plywood and offer comfortable seating so that the owners can enjoy views out into the garden. 

As space is limited, this integrated solution also means that there’s no need to bring in more furniture, which would reduce the available floor area. The muted colour palette compliments the pared-back interior design helping to establish a calming retreat.

'We left the beams in the master bedroom and spare room exposed, ' continues Daniel, 'and we painted them the same colour as the walls to create a greater sense of space and depth.'

'Built-in wardrobes make the most out of the eaves,' continues Daniel, 'and we’ve also integrated hidden storage behind the clothes rails. Angled brass skirting helps create an optical illusion of more height and adds to the crisp and clean aesthetics. Glazing also plays an important role by bringing in natural light in each section of the new loft.’

In the bedroom, the loft conversion ideas feature exposed beams have been completely modernised and painted in the same shade as the walls so that they blend in. Matt black downlights and wall-mounted lighting have been carefully positioned to create a sense of symmetry that’s replicated throughout the loft area. 

The bed is almost level with the window seat so there are no obstructions of the garden views. Sections of the walls feature a layer of rubber and cork material - these both contrast against the black features, but also have a functional use, too. The material has acoustic insulation properties so it effectively absorbs sound.

Plywood cupboards have been fitted under the eaves and reflect the same material directly opposite it surrounding the window. Storage, while essential, has been designed to blend in as much as possible so as not to create a distraction. 

The minimalist handless design ensures the scheme maintains an uncluttered look, all in keeping with the idea of creating a space to unwind.

Hallway doors

In order to maximise the available floor space in the new loft, one of the many one clever storage solutions for the small spaces that the architects created was the  doors for the master bedroom and ensuite. 

With both doors open, you gain access to the bedroom and en suite. Close them and that section of hallway effectively becomes an additional section of bedroom, with the ensuite closed off from the rest of the floor. 

These bespoke doors feature magnets on each leaf that help keep them fully open at 90° and feature a flush finish. Here (see above) the doors are open and conceal the cork and rubber wall. 

When the right door is closed (see below), it allows for privacy in the bathroom space and on the left, it helps contain the guest bedroom. The black colourways used conforms to the minimalist style that’s been adopted throughout.

When the hallway doors are closed, a section of the corridor becomes incorporated into the master bedroom. This section of hallway also features a large rooflight with an integrated blackout blind.

The bathroom

The modern bathroom ideas feature clean and uncluttered fixtures and fittings with wall-hung sanitaryware making the space feel bigger. The walls have been covered in marmoleum that’s made from 97% natural raw materials that is CO2 neutral. 

Marmoleum is a practical low maintenance surface is both durable and offers a simple, clean finish with no breaks as you would have with wall tiles. 

The windows have been positioned to create a sense of more space than there actually is, giving an elongated appearance.

The attic bathroom ideas also feature a compact walk-in shower, there’s no glass enclosure to keep clean, but the wall helps contain the water. 

The same marmoleum material has been applied onto the floors using a different pattern that reflects the texture of the cork and rubber walls nearby. Again, sleek matte black shower fittings help finish the contemporary look.

The guest bedroom

The guest bedroom can be used as a multifunctional space with moveable furniture enabling the owners to adapt it to their needs. Here, the olive green walls and dark floors present an effective contrast, while the window guides your sightline out towards the garden.

The space feels bright despite the deep hues that have been adopted, with the light-coloured furnishings and ceiling adding to the sense of airyness.

The property before works began

The terraced property had a standard, cramped Victorian setup which didn’t meet the needs of modern family life. The owners needed more space for their growing family, as well as a guest room to host visitors. The existing layout only had two bedrooms and didn’t maximise on the existing floor plan.

Focus on: Dormer loft extensions

Daniel Rees From Rees Architects gives us the lowdown

• CONSIDER CLEARANCE A minimum head height required is between 2 and 2.2m, so if your loft is currently under 2.5m then it will be difficult to make it work once the structural space is taken into account.
• ADDING LIGHT Placing a roof window directly above the staircase in a dormer extension is a smart way to bring light into the house. If the loft room is small then it’s also an idea to leave the staircase open to the room and put the entrance door to this area on the floor below.
• STICK TO THE RULES Permitted development and most planning policies do not allow you to raise the ridge of the roof, although if your neighbours have higher roofs then it might be possible, but still unlikely.
• STRETCH IT OUT Hipped roofs (those featuring three or four slopes to the roof), rather than the usual two, may allow you to extend across the entire roof line, so long as it doesn’t go above the highest ridge line.
• TOTAL SPACE Under permitted development, you can add up to 40 cubic metres to a terraced house, including an end of terrace. This goes up to 50 metres for semi-detached and detached houses.

Converting your loft can ease space pressures on your home, and add value, without needing to change the overall footprint. But a key factor for anyone wanting to tackle a project like this will be to determine how much a loft conversion costs.

With so many different loft conversion ideas possible, the costs can vary wildly. But I've spoken to loft conversion experts to reveal how much the different options will cost. I've also looked at how this cost can change depending on where you live in the country, and reveal how much more you can expect to pay if you live in London.

If any of the figures make your eyes water, I've also shared my advice as an experienced renovator on what you can do to lower the price.

How much does a loft conversion cost?

'An average loft conversion cost can range anywhere from £50,000 - £90,000 and upwards,' explains MD of Simply Loft Rob Wood. 'The typical cost of a loft conversion is based on many factors such as size, type of loft, where you are located in the UK and any internal specifications that are required such as windows, doors, bathrooms etc.'

For example, if you are planning a loft conversion to be a new principle bedroom suite with bathroom within the conversion you will need to factor in plumbing, making it a more expensive project than if you just want to use it as a hobby room.

The price may also be affected by how suitable your loft is for conversion.

We asked Rob how much homeowners can expect to pay for different types of loft conversions. All of these estimated costings include VAT.

• A rooflight conversion starts at around £50,000
• L-shaped conversions start at around £50,000
• A rear dormer loft conversion begins at £55,000
• A hip-to-gable loft conversion starts at £60,000
• A mansard loft conversion starts at £69,000.

However, if you live in London, you can expect to pay around 20-25% more than elsewhere in the country. This is due to higher labour and material costs, and potential challenges that come along with access to deliver materials or undertake the work.

To illustrate this further, let's take a couple of examples. Resi states that a mid-range, average size (45m2) rooflight conversion outside of London will cost an average of £57,500 to build. However, for the same thing in London, you can expect to pay about £70,000 for the construction (not including VAT).

For a hip-to-gable loft conversion, with no dormer, and of the same size and spec, would cost around £72,500 outside of London, rising to £92,500 if you live in the capital.

A mansard loft conversion, outside of London would have average build costs of £72,500, according to Resi, whereas the same thing inside London would cost around £87,500.

What is the cheapest type of loft conversion?

The cheapest type of loft conversion is a rooflight loft conversion, which should definitely be considered if you want to convert your loft on a budget. 'This is the cheapest method as it does not alter the structure of your loft roofline,' says Rob Wood. 'However, whilst this is the cheapest type of loft conversion, it may not maximise the space potential of your loft.'

Adding a dormer window might add to the costs, but could be absolutely worth it if it provides you with additional usable floorspace.

What's the most expensive type of loft conversion?

A mansard loft conversion is usually the most expensive type of project, but costs can also go even higher with a high spec modular loft conversion (where the room is assembled off-site and craned into place).

If you live in a home with a flat roof, you might think a loft conversion is impossible. But as Rob explains, it may be more possible than you think. However, it's not cheap. 'The most expensive type of lofts to build are London Valley (butterfly) roofs or flat roofs, where there is no loft cavity to convert i.e. you are effectively doing a second floor extension,' he points out. 'These start at around £80K upwards depending on size.'

What can affect the cost of your loft conversion?

Effective budgeting is key if you want to avoid loft conversion mistakes. If you are trying to cost your loft conversion project, you'll need to take various factors into consideration.

• Where you live. Converting a loft in London will cost 20-25% more than other parts of the UK.
• Type of property. The loft in a terraced property may be smaller in area than a detached house, but it could be a more challenging project, which would affect the price.
• Roof pitch and structure. If you live in a house with a steeply pitched roof, you might have enough head height in order to go for a cheaper type of conversion. However, if your roof has a shallow pitch, you will need to opt for something more expensive to make the space usable. When it comes to structure, trussed roofs can be more complex to convert, which can mean additional costs.
• What you want to use the new space for. If you’re interested in attic bathroom ideas or in adding a kitchen into your loft this will put up the price due to the extra expertise and labour required. Rob adds: 'Budgeting for your loft conversion all depends on the type of transformation you desire. For example, if no exterior alterations are needed it will be cheaper.'

How can you lower loft conversion costs?

Thankfully, whatever type of loft conversion you want, there are ways of cutting costs.

In fact, Checkatrade estimates that costs can come in as low as £27,500 for a 30m2 skylight loft conversion. If that's closer to your available budget, then make sure you follow these tips.

Shop wisely

'You can alter the price of your conversion by choosing cheaper fittings, such as your windows and doors,' explains Rob Wood.

'Avoid using blockwork or brickwork for any of the side walls of the loft,' further advises Rob Wood. 'Try and use stud work (wood) clad in tiles as this is more economical and quicker to build.' Some types of exterior cladding will also be cheaper than others, so do your research.

Stick to the plan

'You should also try to avoid changing your mind midway through a project,' continues Rob. 'The more changes you make, the longer the build will take and the more it will cost. You should aim to agree on as much of the scope with a contractor before signing up.

DIY where you can

With any kind of renovation project, you can save money by doing some elements on a DIY basis. But it's crucial that you only attempt tasks that are within your capabilities, otherwise you could end up paying more to get a professional in to rectify your mistakes.

Keep glass to a minimum

'And, finally, avoiding lots of windows and expensive glazing in a loft conversion will also help to keep costs lower, although we do recommend a minimum of two to three windows to keep the conversion feeling bright,' concludes Rob.

FAQs

Is a loft conversion cheaper than an extension?

If you are considering building an extension instead of converting your loft you will be interested to learn that, in most cases, it is cheaper to convert a loft than build an extension. The cost of building the average extension lies somewhere between £1,500-£2,250/m². Loft conversions come in at lower than this, starting from around £900/m2, although they can rise to £2,500 in some areas and for some designs.

Unlike extensions, lofts are relatively self-contained in the early stages of building. They can be accessed from the outside – meaning you can continue living in the house while work is underway. Consider this a cost-saving bonus, there are no temporary extra living expenses to factor in.

Will a loft conversion add value?

When determining whether a loft conversion will add value, you might also be weighing up whether that's a better option than moving to a different property that may better suit your needs.

According to the Royal Institution of Chartered Surveyors (RICS), the cost of the average basic loft conversion equates to one third of the cost of moving to a new property with an extra room. The Institution also predicts it could increase the value of your home by approximately 25 per cent.

As well as loft conversions, there are other brilliant ways to add space without extending – sometimes a remodel of the existing layout can help. You should also take a look at some brilliant garage conversion ideas – you might just find you have the space you need for that extra guest bedroom after all.

Planning a loft conversion can be a complex process, but getting it right is essential if you want a project than runs smoothly and a successful result.

And it's well worth considering some loft conversion ideas as a solution to a home that's not currently meeting your needs. If there's one thing I've learned in my years of experience as a homes journalist writing about renovation, is that the most cost-effective way to add space to your home is to make better use of the space you already have.

Here I break down where you should start with a loft conversion, what options are available to you, how long it takes, as well as answering the common FAQs that homeowners have before taking on a loft conversion.

How to plan a loft conversion

These are the steps and decisions you can expect to make when converting a loft. By following these, you can plan effectively and hopefully dodge common loft conversion mistakes that could leave you dissatisfied with the final result and out of pocket.

1. Check your loft is suitable for conversion

Before you get your heart set on a loft conversion, you need to assess whether your loft is suitable for conversion in the first place. You will usually rely on a loft conversion expert to determine this for you, but it never hurts to be as clued up as you can be.

‘Most properties will be suitable for a loft conversion as long as the loft measures 2.3m at the highest point. Other features that will help you decide whether your loft space is suitable are the pitch of the roof, the type of structure, and obstacles, such as water tanks or chimney stacks,’ explains John Allen, managing director at Econoloft.

Pre-1960s buildings are often the easiest to convert, thanks to their steep roof pitch and traditional framed roof.

On the other hand, post-1960s properties often have a more complex trussed roof structure. It's not impossible to convert a roof like this, but it's a more complicated process, which will usually make it more expensive.

Regardless of the property you live in, there will always be structural considerations to be made. Most lofts need additional support from steel beams to strengthen the floor and roof. Foundations should also be checked to make sure they are fit to support the additional load. If not, then a structural engineer will be needed to determine the best solution.

2. Choose your loft conversion route

Loft conversions are complex projects so it's best to use a professional. You could use an architect or architectural designer for your loft conversion, or you could opt for a specialist loft conversion company instead.

Whoever you choose, make sure you ask the following questions:

• Do you need planning permission for a loft conversion?
• Do they have public liability insurance and what does this cover?
• Are they registered with an official trade body?
• Are they registered with a competent person scheme. Will they take care of all planning permissions / building regulation approvals?
• Do they offer insurance-backed warranties?
• How long have they been trading for?
• Can they give you up to 3 references of recent work they’ve completed?
• Do they use sub-contractors or their own employees?
• What experience do their sub-contractors/employees have and are they covered by insurance?
  

Don't be afraid to contact their previous clients. The likelihood is that if they are pleased with the result they'll want to shout it from the roof tops, and if not, they'll definitely let you know!

3. Find out what permissions you need

The next step is to find out whether you need planning permission for your loft conversion and get to grips with the building regulations you'll need to meet.

In many cases, you will be able to convert your loft under Permitted Development (PD) which means you won't need to apply for planning permission.

However if you live in a listed building or a designated zone, like a Conservation Area or National Park, then you will need to apply for planning permission for your loft conversion. This is because your PD rights may have been restricted or removed altogether. It's best to check with your local authority before you begin to make sure.

If you want to build something that goes beyond PD criteria, then you will also need planning permission. These criteria include:

• Materials must be similar to those used in the existing house.
• The size should not exceed the original roof space by more than 40 cubic metres for terraced houses or 50 cubic metres otherwise.
• The conversion must not exceed the height of the existing roof.
• The eaves of the original roof are maintained (or reinstated).
• You will need planning permission to include verandas, balconies or raised platforms.

Loft conversion building regulations will apply regardless of whether you need planning permission or not. If your loft conversion takes your home's usable space over three floors, then you will also need to adhere to fire door regulations.

If you live in a semi-detached or terraced property, then you may also need to have a party wall agreement in place. If you're worried your neighbour might stop you converting your loft, we asked the legal experts where you stand and what you can do.

4. Work out your budget

Cost is a hugely influential factor when it comes to any kind of renovation, and a loft conversion is no different. So you'll need to determine how much a loft conversion costs to see what you can afford.

If you want to convert your loft on a budget, the cheapest type of loft conversion is a rooflight loft conversion (sometimes called a VELUX loft conversion), which doesn't involve any external alteration to the roof, apart from the addition of a rooflight or two.

The most expensive type of loft conversion would be a mansard loft conversion.

The size of your loft will understandably influence the cost, as will the type of property you live in and the specification you choose.

Detached homes can be relatively straightforward, but terraced properties, with their potential access issues and the fact they share walls with neighbouring properties, can see costs totting up.

5. Decide on the type of loft conversion

The best type of loft conversion will largely be influenced by your budget, current roof structure and the amount of space you are looking to create. Your loft conversion company will be able to advise on the best option for your home.

In homes that already have a steeply pitched roof, a simple rooflight loft conversion could easily be possible. If your roof pitch isn't as steep, then you might need to create additional headspace by adapting the shape of the roof, which will increase the amount of usable floorspace, with a dormer or mansard loft conversion.

6. Determine how long your loft conversion will take

How long a loft conversion takes will depend on the type of loft conversion you opt for, where you live and whether there are any unforeseen issues along the way. Somewhere in the region of three to four months is reasonable.

For the build itself, you are looking at anything from about four weeks for a rooflight conversion, about six for a dormer and up to eight weeks for a mansard loft conversion.

Add on to that between two and four weeks to finalise the design, around 12 weeks for planning permission and party wall agreements (if required), and another couple of weeks for finishing touches.

However, if there are planning concerns, material shortages or inclement weather, these can all cause delays to your project.

7. Assess the level of disruption you could face

Fortunately, the disruption caused by a loft conversion is relatively minimal as most of the work will be contained to the loft space (and accessed from the outside with scaffolding) for the majority of the project. But it's still a building project, so some disruption is to be expected.

‘If structural changes are required, such as installing new beams or reinforcing the floor, it may involve some noise, dust, and temporary inconvenience, and if a bathroom or additional electrical wiring needs to be installed, there may be some disruption to existing services. However, experienced contractors can often minimise this by careful planning and co-ordination,’ says Daniel Kerley, company director at Loft Living.

If the project becomes too disruptive, you may want to decamp elsewhere if you can until the work is complete.

8. Decide on how to heat, ventilate and insulate a loft conversion

You'll need to check that your existing boiler can cope with the additional heating and hot water demand. If not, you will need a new one.

Water pressure will be a key consideration too. ‘You’ll need to check your water pressure. Adding in an extra floor means water has further to travel upwards which can cause issues. This can easily be alleviated by installing a pump to generate water pressure: you’ll need to know before plumbing things in whether a pump is required,’ says Barrie Cutchie, design director at BC Designs.

We all know that hot air rises, which means lofts can get warm. Having an openable window at each end of the new space can help provide decent air flow.

When it comes to insulation, there are two options, but Building Control will specify the type you need.

• The cold roof method. This involves filling the space between the rafters with 7cm-thick slab foam insulation, with a 5cm space between the roof felt and the insulation for ventilation. Then a 3cm of slab insulation is then attached to the inside of the rafters. This gives a total of 10cm of insulation. The roof section of the loft conversion will require 30cm of mineral wool insulation, or 15cm of slab foam insulation.
• The warm roof method. This method involves installing 10cm of insulation on top of the rafters, and a covering capping, followed by the tile battens and tiles. This is only really an option if the roof covering has been stripped off, like when a dormer is being added. The dormer walls can be insulated with 10cm Celotex between the studwork.

9. Choosing loft conversion stairs

Whether you choose an architect or a loft conversion company to create a new room in the loft, they will be able to advise on the best place for your loft conversion stairs to go.

They'll make sure the stairs meet all the necessary guidelines in terms of head height, number and size of the steps, and any balustrades. They will also advise on the best location for them, and ensure they feel in-keeping with the rest of your home.

10. Inform your home insurance provider

Before work starts on your loft conversion, make sure you let your home insurance provider know, otherwise you could invalidate your policy.

Not all policies cover building work, like loft conversions, so you might need to take out specialist renovation insurance.

FAQs

Can I include a bathroom in a loft conversion?

You can add a bathroom to your loft conversion, but it's positioning should be planned carefully.

‘The difficulty of incorporating attic bathroom ideas depends on the loft’s current layout, the available space, and the proximity of existing plumbing and drainage systems,’ says Daniel Kerley.

‘With plumbing, the cheapest and easiest way is to make sure your new bathroom sits over the top of an existing one. It makes running water and soil pipes much easier,’ adds Barrie Cutchie.

There may need to be further structural considerations too, as Barry explains: ‘Depending on the weight and load-bearing requirements of the bathroom fixtures, such as the bathtub or shower, you may need to reinforce the floor structure. This could involve adding extra support beams or joists to ensure the loft can accommodate the extra weight.'

How can I prevent my loft conversion from getting too hot?

Hot air rises, and as a result, your loft conversion will naturally be the warmest room in the house. Therefore, it is vital to factor in cooling methods.

Sensor-operated windows – that open when the temperature reaches a certain level and close if rain is detected – are a great option. ‘Consider installing windows that can be opened to create cross-ventilation and using extractor fans or mechanical ventilation systems to enhance air circulation,’ advises Daniel.

You can pair windows with blinds or curtains to restrict the amount of light (and heat) that enters the space during the hottest times of the day.

Can I add storage to a loft conversion?

If you store things in your loft, you might be concerned about what to do with that stuff if you choose to convert it to living space.

But fortunately a loft conversion doesn't take away all of your storage solutions. Under the eaves is the perfect place for a bit of additional storage, which can be factored in to your loft design.

Bespoke furniture that fits to the contours of a sloped ceiling will help to maximise storage space, and make the new room feel polished.

Once you'd added the physical space, follow these expert tips to make it look it's best.