How to insulate a shed – step by step for keeping a shed warm and dry

Find out how to insulate a shed in this guide to keeping it free from damp, mould, heat and cold
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  • Knowing how to insulate a shed might sound excessive for what is often a glorified storage space, but there are numerous reasons why it’s a good idea.

    Energy-efficiency is the buzz word when it comes to insulating your home, but it is also worth protecting your shed too.‘By keeping the shed temperature regulated, it’s easier to keep it looking its best and helps avoid damage from rust and insects as well as damp and mould,’ says Tony Kersey, Homebase Buying Manager.

    ‘Having an insulated shed means that you’ll create an optimum environment for both you and the shed,’ adds B&Q Category Planner James Benfield. ‘This is necessary if you’re storing weather-sensitive equipment or electronics, such as lawn mowers or strimmers.’

    How to insulate a shed – step by step

    black shed at the end of garden

    Image credit: Future plc/Colin Poole

    ‘Insulating a timber shed is relatively easy to do yourself,’ says Jenny Davis at Forest Garden. ‘DIY stores have everything you need to tackle the job over a weekend. Whether it’s a tool shed, garden office or potter’s retreat, when your structure is free from drafts and moisture the possibilities of what you can store in and do with that building are endless.’

    1. Work out how much insulation you need

    Measure the height, length and width of your shed floor and walls and include the space for the studs in this. ‘Don’t forget to measure the height and width of any windows and doors, then multiply the measurements to find the area of each window or door and subtract them from the total square meterage of the wall and floor,’ says Rated People builder, Nathan Hyatt-Mitchell. ‘When it comes to the roof, you’ll need to measure between the rafters.’

    2. Choose which shed insulation to use

    There are various types of insulation, depending on where you want to position them – roof, walls, floor. Most are available as rolls or boards, which are fitted between wall studs and roof joists and then covered with plywood. If you’re really trying to save money, there are ways to insulate a shed for free.

    ‘When selecting the insulation for your shed consider cost, efficiency, insulation properties, use of the shed and ease of installation,’ says Monica Cleere, ToolStation.

    Types of shed insulation

    white garden shed

    Image credit: Future Plc / David Giles

    Mineral (stone) wool (aka Rockwool)

    Available in slabs, stone wool is easy to lay vertically or horizontally. It’s denser than fibreglass (see below), has good thermal and acoustic qualities and is non-combustible. Protective equipment is required when handling.

    ‘Because of its sound-proofing properties, stone wool is great if you’re looking at turning a shed into a workspace,’ says Rose Milner. ‘Stone wool boards usually friction fit between studs so don’t require fixings, making them easy to install. However, you’ll also need breather membranes and vapour control layers to prevent any damp ingress, which can eat into the usable space.’

    PIR or foam slabs/boards

    Great for heat retention and sound-proofing, these lightweight boards are easy to cut and install. They can be used for suspended wooden floors, pitched roofs and internal walls, and secured with adhesive or ‘friction fit’. These would suit those who use noisy power tools, due to their thermal and acoustic properties.

    Multi-foil

    ‘Multi-foil is an excellent option for sheds, and is often more cost-effective than PIR as well as being simpler to install,’ says Rosie Milner. ‘Although, if you were converting your shed to a garden room, it does require air gaps to be the most effective and wouldn’t work so well in a fully-sealed environment.’

    Sheeps wool (thermafleece)

    Made with 75% British wool and 25% recycled polyester, thermafleece can be installed without gloves or protective clothing. It’s breathable, durable and easy to install. Cosywool slabs friction fit and don’t slump, so they’re great for shed walls.

    Hemp

    If you prefer plant fibres, Natrahemp fleece can be handled without gloves, fits securely between studs, joints (or rafters), and provides excellent thermal and acoustic insulation.

    ‘We would recommend natural insulation, like sheep’s wool, as it’s less prone to slumping,’ says Rose Milner. ‘PIR board or multi-foil insulation are also good. All of these options are simple to fit and don’t require moisture protection – and unlike fibreglass, only minimal PPE is recommended, making them ideal options for DIYers.’

    Fibreglass wool

    Generally used for roof and loft insulation, fibreglass wool is available in rolls, relatively inexpensive and simple to install. However, it’s vital to wear protective goggles, mask and gloves when handling glass wool, as it’s itchy to work with and the tiny fibres can irritate skin, eyes and lungs.

    ‘Fibreglass loft insulation is not ideal for sheds,’ says Insulation Superstore’s Rosie Milner. ‘It’s more suitable rolled out in the loft, as it’s susceptible to ‘slumping’ if installed vertically.’

    3. Clear the shed and prepare the space

    Empty your shed completely and make any necessary repairs. ‘Check for any leaks, damp and gaps and seal with a wood-based sealant,’ says Rated People builder, Nathan Hyatt-Mitchell.

    ‘A shed will lose heat through the roof too, so secure any loose roofing material externally and seal around the doors and windows with silicone or spray foam too.’

    4. Make sure you have the right equipment

    Thermawrap foil insulation

    Image credit: ToolStation

    Once you’ve chosen the insulation, check the manufacturer’s recommended list of tools required and specific installation instructions. Depending on the insulation you’re using generally you’ll need a dust sheet, staple gun, stanley knife, measuring tape, hammer, nails, adhesive and a hand saw, plus protective goggles, gloves and overalls if required.

    If you’re including the inside of a pitched roof you’ll likely need a step ladder and a friend to hold it too.

    5. How to insulate a shed

    Cut strips of insulation by length and width to fit between each stud in the walls, pitched roof or floor. Deal with any obstacles that might get in the way of the insulation being laid and (if required) add a vapour barrier.

    ‘Press the insulation gently between the two studs and be aware the moisture barrier must face towards the room,’ says Rated People’s builder, Nathan Hyatt-Mitchell. ‘There are various options to secure the insulation; use a staple gun for walls and use steel wire for floors.’ Of course if you’ve chosen ‘friction fit’ this can just be wedged between the studs.

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