How to plan a kitchen extension

Make room for your dream kitchen with an extension. Beautiful Kitchens' step-by-step guide takes you from brief to build.

Adding an extension is a great way to open up your kitchen. Not only can it create more space for cabinetry or an island, it could even allow you to turn your room into a kitchen-diner.

How long your extension will take to build will depend on the complexity of the project, but as a rough guide you should start planning the type and size of extension at least six months before your preferred day of completion.

Making initial plans

The kitchen layout needs to be decided early on so that all of the electrical and plumbing services can be positioned to suit your plan. ‘Work on the big picture, looking at all aspects in broad detail (outline design). Then introduce accuracy (scheme design) and fill in the detail (detail design),’ advises Hugo Tugman, founder of Architect Your Home.

Think about how much additional space you want your extension to provide, and overall budget. Homebuilding website Design Your House predicts that you can expect to pay around £1000sq m for a low-cost construction with no site constraints, and budget fittings and specification. This figure roughly doubles for a more complex structure with luxury features.

Choosing an architect

Once you’ve decided on a style and space, look for an architect or designer who will be able to advise you on what’s possible, guide you through the planning process and help you work on a budget. Make sure your architect is RIBA Chartered and make use of recommendations from family and friends.

When you have a shortlist ask to see example’s of the architect’s previous work and to speak with former clients. Your chosen architect will then undertake a site survey and present plans to you for approval.

Building regulations and planning permission

Once you have approved the architect’s plans you will know whether the extension falls under permitted development, or if you need to apply for permission. For advice about planning permission, visit Directgov. Under permitted development, you will still need to obtain building regulations approval. Building regulations apply to most work and ensure safety and energy efficiency. You can choose between a local authority inspector or private approved one, which may be quicker.

If you’re applying for planning permission and your house isn’t listed or subject to restrictions, your architect can submit the plans for you. Allow at least eight to ten weeks for the application to be processed. You may also require approval under the ‘Party Wall’ Act, which is a wall that stands on either side of a boundary of land belonging to two or more owners. Works with foundations within certain distances of the walls also fall within the act, not just work to the wall itself.
Finding a builder

When looking for a builder, try recommendations from friends and family if you like the look of their extensions, or you can post a job on Ratedpeople. Make sure any builders you request quotes from are TrustMark approved. Your architect should also be able to suggest contractors they’ve worked with before. Make sure to get references and check that they have relevant insurances and guarantees.

Costs vary for building works, and it is an idea to get several prices. Allow at least three weeks for contractors to prepare their prices, as they themselves are relying on sub-contractors to price parts, and then ask them to submit a proposed schedule.

Getting started on site

Once you have planning approval, Party Wall Agreement and a kitchen on order, the building work can begin. While preliminary works get under way, ‘second-fix’ design decisions and a tender can be made about finishes, lighting fittings and tiling.

You’ll need a contract with your builder and your architect can advise you on the type required. ‘Most contracts require staged payments against valuations,’ says Hugo Tugman, founder of Architect Your Home. ‘This means that your architect visits the project every payment period and issues a certificate to say what percentage of the total work is complete. You then pay against completed works.’

Allow plenty of time for flooring to be ordered.

Final stages

Once the building work is finished, any snagging issues can be dealt with. Snagging refers to the knock-on structural and finish effects of the building settling back on its foundations after the work is completed. Only when these have been done to your satisfaction should you make your last payment to your builder in return for a final certificate. Make sure that all electrical work, plumbing and gas supplies are signed off, too.

Before your kitchen cabinetry and appliances can be installed, you’ll need to lay your flooring. Then, fitting of your new kitchen should take up to four weeks. After the cabinets have been fitted, your kitchen company will template the worktops, which should take around two weeks. In the meantime, you can paint the walls and add fixtures and lighting. Then, once the worktops are in place, you’re done.

Useful kitchen extension contacts

Find an approved building inspector at the Construction Industry Council

For information about homebuilding, visit Design Your House

Details of planning permission can be found at Planning Portal

Find a RIBA Chartered architect at RIBA

For registered builders, try TrustMark

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