When it comes to extending your home, the two major questions on your mind will probably be: how much will it cost and how long is it going to take?

On both of these points, it can be a challenge to get one set number, as every project is its own unique thing. However, for anyone who wants to get a rough idea of what the calendar will likely look like, we’ve caught up with the team at Resi.co.uk.

As the UK’s leading home extension platform, Resi has helped over 4000 renovators bring their ideas to life, so know a thing or two about timings. Their unique platform provides everything a homeowner needs to get their project onsite, including design, planning, surveys, finance, contractors, and much more. Therefore, if anyone knows the ins and outs of building an extension, it’s these guys!

Here is a breakdown of the key stages most extensions will face and the timings involved. 



2-3 weeks

How long will my extension take

Image Credit: Resi

So, you’re ready to extend and get things kicked off. The first thing you’re going to need is a set of existing drawings. If you don’t already have drawings of your home as it stands today, then you’ll need to hire a surveyor to carry out a measured survey.

The survey itself shouldn’t take longer than a day to complete. However, you should budget time to find a surveyor and find a time for them to visit your home. 

How your survey will be carried out will depend on the type you opt for, either a traditional hand survey or laser variety. Hand surveys can take between 4-5 hours to complete, while a laser survey can be done in as little as 45 minutes. Laser surveys also offer more accuracy, as they create a digital twin of your home, rather than just taking down a few measurements. 



2-5 weeks

How long will an extension take

Image Credit: My Bespoke Room

With your existing drawings in hand, you’ll be ready to start working with a designer. You should factor in time for an initial conversation on ideas, the first round of drawings, plus at least one set of revisions. If the process runs smoothly, you can get your designs on paper within a month, though this will vary depending on the number of changes you request. 

Once you’re happy with how your extension has been drawn together, then your designer can package up their work, ready for the planning stage. 


Tackling an extension? We can use your architect's plans and help you create a cohesive, functional and beautiful space. Our consultancy service starts from £195 for four hours. Book a free call with us now so we can set this up for you!




8-10 weeks

extension planning

Image Credit: My Bespoke Room

Whether you’re going down the route of traditional planning or permitted development rights, you’ll still need to factor in 8-10 weeks in order to obtain either approval or a lawful development certificate.

The bulk of this time will be spent waiting for your local planning authority to review your application. However, you should also allow time for the application to be validated. 


Building regulations

4-8 weeks

timeline of an extension

Image Credit: Resi

While the drawings prepared during the planning stage were concerned with the future look of your property, you’ll still need to flesh out the technical details before you get onsite. At a minimum, this will involve working with a structural engineer, but you may choose to take things a step further and commission of building regulations package. 

At Resi, we always recommend you take the time to invest in a building regulations package. Their benefits include…

  • Your technicians will provide a detailed set of drawings, ensuring your future space meets all the legal requirements. This protects you both in the eyes of the law and ensures you spot any issues before construction takes place.
  • The level of detail in this package means contractors can provide a better quote during the tendering stage, as well as have a comprehensive plan to work from during construction. 

Though this may draw out this stage of your project, it's always better to be safe than sorry when it comes to regulation! 


Tender process

2-4 weeks

planning an extension

Image Credit: My Bespoke Room

The tender process is just a fancy way of saying that you’re hiring a builder.

It’s recommended that you have at least three quotes when it comes to choosing your contractor. To make sure you get these three, we would suggest approaching five or more contractors.

If you’re looking for a place to start when it comes to finding a contractor, you can try approaching family and friends for their recommendations. Remember, you don’t need a license or any other kind of qualification to be a contractor, so it’s important to find a professional that’s trustworthy.

You may also find your architect or other professional might be able to help, as they’ll have regular contact with professionals in this sector and will have established good working relationships with the best of them. 



2-4 months

Landscape blog image 600 width (15)-1

Image Credit: Resi

Construction is where all your hard work pays off, but it can be a very intense process. From your foundations, masonry, to roofing, there’s a lot that goes into a new house extension. That’s why the entire process tends to take between 8 to 16 weeks. 

An important decision you’ll need to make is whether or not you want to live on site. While renting can be very expensive, sometimes a short term rental is the best option. Don’t forget, there will be dust and scaffolding; your water might be turned off; site waste might need to be moved through the house if you don’t have any other site access. Basically, it’ll be a very unpleasant place to live.

Before works begin, it would be worth sitting down with your contractors to understand the realities of what construction is going to be like. 

And there you have it, your extension is in the world, ready for you to make your own. For more advice on building a new extension, book a free Resi consultation or get a quote for their services in minutes.  


If you want an expert second opinion on your plans our consultancy package could be just what you need. The service starts from just £195 - find out how it works or to book your free, no-obligation consultation:



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