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​How to build your perfect kitchen DIY extension

Johannes van Graan Johannes van Graan
Ashley Road Modern balcony, veranda & terrace by Concept Eight Architects Modern
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Out of all the home renovations, DIY and makeover projects, creating a large and open-plan kitchen extension is probably the most popular. Due to its benefits (like more space for entertaining), a spacious and stylish kitchen is one of the most sought-after features in a modern home. 

After all, a kitchen is not just about cooking and eating – it's where a family can spend quality time together by socialising, working and relaxing. However, before we can pick out stools for the new island, we have to start at the beginning: knowing where the new space is going to come from, getting the layout right, and having a look at some estimated costs…

1. How much will it cost?

Kitchen, dining room and folding doors opening to garden Modern kitchen by Holloways of Ludlow Bespoke Kitchens & Cabinetry Modern Wood Wood effect
Holloways of Ludlow Bespoke Kitchens & Cabinetry

Kitchen, dining room and folding doors opening to garden

Holloways of Ludlow Bespoke Kitchens & Cabinetry

The overall price will vary depending on the amount of work being carried out, although these numbers can serve as a guide:  

• Redesigning work can cost £500-800 per m². 

• Converting a garage will be about £950-1,250 per m². 

• A basic extension can cost you £1,050-1,450 per m². 

• A more individual extension with bespoke windows and doors will cost £1,450-1,850. 

• Cellar conversions cost £950-1,150 per m². 

• New basement extensions can be around £2,500-4,000 per m².

2. How much space will be needed?

Headlands Cottage - Interior Modern kitchen by Barc Architects Modern
Barc Architects

Headlands Cottage—Interior

Barc Architects

That all depends how you plan on using your new extension. Ask yourself these questions first:  

• Will your kitchen be solely for preparing meals, or do you require dining space too? 

• Do you want to be visible when cooking, or tucked around a corner? 

• Will you entertain in the kitchen, or only have informal dining there? 

• Do you want the kitchen to share in some open-plan living space?  

• Do you need a separate utility room, larder or store?

3. How to find the required space

If you want your kitchen to have access to the garden (or some privacy), it is likely to be situated at the rear of the house. For easy access, it should be accessible from the main hallway and not through another room. 

The extra space may be achieved by remodelling the existing layout, removing a few internal walls to link two rooms together, or converting and linking an internal garage.

4. How to find the required space

​Kitchen and sitting area with views of the back garden at Bedford Gardens house. Modern kitchen by Nash Baker Architects Ltd Modern Glass
Nash Baker Architects Ltd

​Kitchen and sitting area with views of the back garden at Bedford Gardens house.

Nash Baker Architects Ltd

Another option would be to extend the rear or side of your home to gain some extra space. If you live in a townhouse, it might make sense to convert and/or extend the cellar to form a basement storey, with a lightwell leading up to the back garden.

Small extensions to your house may not require planning permission if they fall within the definition of permitted development. But larger extensions, or additions to a flat, will always entail planning permission. 

Alterations to a listed building always require listed building consent, whether or not the work is permitted development.

5. How to design your kitchen extension

Should you be planning on redesigning your home and making only internal alterations to create more space (such as knocking down a wall between the kitchen and dining room), you could draw up the layout plans yourself to scale, and then commission an engineer to prepare drawings and calculations for the structural alterations for submission to the local authority and to pass on to your builder.

No planning permission or other drawings will be required. However, if your property is leasehold, permission from the freeholder will need to be obtained. 

If you plan on extending to gain more space, you will need drawings of the layout, elevations and all the design details, showing how the project will comply with the Building Regulations. It’s best to leave these drawings to a professional, such as an architect or an architectural technical designer.

6. How to design your kitchen extension

Major renovation, extension and loft. Fulham W6 Modern kitchen by TOTUS Modern

Major renovation, extension and loft. Fulham W6


It is quite crucial to get the design of the space correct, as this will help to ensure the kitchen is in the right location, plus offers easy access from the central hallway. It will also help you gain the most light, plan your different zones for cooking, dining and living, plus decide where to position utility space and appropriate lighting.

Once your space is all set out, you can start thinking about the kitchen’s layout. We recommend consulting two or three experienced kitchen planners for their expert ideas. Make sure you give them a clear brief of what you are trying to achieve, but listen to their advice in terms of layout to suit the space (such as designing an L-shaped layout, or introducing an island or appliance wall).

Once the main layout is agreed upon, you can finalise details like cabinetry, worktops, backsplashes, fittings, etc.

7. How to design your kitchen extension

Once you've finalised your layout and chosen your supplier, the designer will be able to produce detailed wiring and plumbing plans. These are to help the builders put the services in place during the building phase. 

Then we move on to having the plastering and decorating work done and the flooring laid, ready for the kitchen installers to arrive.

Good luck, and remember to enjoy it! 

Want to see where you can save some money with your new extension? Then have a look at: How can we cut the cost of our home extension?.

Planning a kitchen extension? Share your ideas, below....
Whitton Drive by GK Architects Ltd Modern

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