Architects Advice When Designing Your Extension







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Embarking on a home extension can feel daunting, particularly if this is your first renovation and you don't know where to start. However, the potential for your home extension to change the way you live is so exciting and will be well worth it in the long run.

We chat to Delve Architects, a dynamic London based Architect practice, who share with us their tips on ensuring the design of your home extension is perfect for now and the future.

Gellatly Road extension, by Delve Architects. Image by Emanuelis Stasaitis.

Where do you recommend starting when thinking of design ideas for a home extension?

Our advice would be to allow yourself some initial thinking space – to let your imagination run free with all the ways in which you would like your dream home to work for you.  

In our opinion, the beauty of architecture is that there is never a right or wrong answer, simply different arrangements of spaces that work for different people at different stages of their lives.

Are you keen cooks, intent on opening up the kitchen as the central hub of the house? Do you long to retreat to a cosy snug at the end of a long working day? Do you want to be able to watch the kids play in the garden while you potter about the house?

Reflect on your priorities, and immerse yourself in the many websites and resources offering inspiration. You might even want to begin creating your own mood-board at the start of the design process, which we can review together and bring to life in the right way for your home.

This window seat is such a wonderful feature of this extension by Delve Architects. Image by Emanuelis Stasaitis.

When it comes to giving your architect a brief on a home extension, what advice do you have?

The main aim when briefing your architect or designer is to be clear about your needs and preferences. Which spaces do you wish were bigger or smaller? Where in the house are you in desperate need of additional storage? Are there any parts of the living space that cause you a real headache? Where in the house do you spend most of your time?

Having all of this clear in your mind upfront will allow your architect to push these themes forward through the design. It will ensure your new home reflects your living preferences and is not held back by stereotypical layouts or constraints.

Also bear in mind that flexibility in design gives a family the right setting to grow without wholesale future redevelopments. A layout within which rooms can change function when required helps achieve this, and we recommend seeing your design as a master plan for the property - giving you a blue print which you can work towards over a number of stages if needed.

A modern larder in this kitchen keeps the space feeling streamlined and uncluttered - by Delve Architects. Image by Emanuelis Stasaitis.

What other considerations are key before a home extension?

Alongside your design brief, there are a number of practical considerations to be aware of before you get started:


It’s advisable to have a ballpark budget clear in your mind upfront. Your architect will use this to guide you on what’s achievable, ensuring any design options presented are feasible based on how much you’re looking to put towards your refurbishment.


Your total project costs will likely include: Council planning costs; professional fees e.g. for an architect, a structural engineer, building control inspector and party wall surveyor; building and materials costs; VAT at 20% (with only a few exceptions); fixtures, fittings and furnishings.


It’s always best to speak to your neighbours at the outset of your project. This can help alleviate any possible concerns before a formal planning application is submitted.

Planning permission

Your local Council will need to grant permission for your design to be realised, including allowing neighbours and local residents the opportunity to comment on your plans. We’ve taken many designs through planning, and it typically takes around eight weeks for permission to be granted, unless you utilise the permitted development rights provided to households.

Appointing a contractor

It’s crucial to find the right building contractor to suit your project and personality. We ask a minimum of four contractors to price each build. This gives a clear indication of build cost as well as inviting different types of contractor to tender.

Delve Architects can chat to you about their design process and any ideas you may have.

If you need more help on where to start, you can use our handy tools, including our cost calculator, budget tool and detailed checklist.

Published: August 23, 2021

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