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How Much Does An Extension Cost?

It’s a tough cookie to crumble this one, but we’re going to try. So you want to know how much it costs to get one of these lovely big kitchen extensions in London? Preferably on a Victorian semi I’m guessing? Well read on…

For a rough estimate, we’re going to assume you have middle ground taste in finishes, kitchens and bathrooms with the odd splurge luxury to bring the whole lot up a level and a few eBay finds thrown in for good measure and character (often the kind of mix we like). To keep it simple, we’ll also assume that your extension is going to be 3 meters which, unless you are in a conservation area will mean it falls under permitted development and therefore no planning is needed.

To start with you’ll want your building plans, structural calculations and to instruct a Building Regulations company. We suggest going through a private company for this rather than the council who tend to be a bit slow when it comes to visits. You’ll need any relevant water permissions and a party wall agreement unless you are detached and surrounded on all sides by a little bit of land, a luxury most of us don’t have… This ‘paperwork’ as we call it is going to come in at around £5-9K mostly dependent on your chosen architect.

Then we get to work! You’re looking at about 3-5 months for a kitchen extension and ground floor remodel, in labour fees that means you’ll probably find yourself somewhere in the region of £35-40K. Building materials go on top of that and again, unless you are having something fancy (which we’re assuming you’re not) you’ll probably be looking at around £35-45K in materials, although always budget more. Materials are a really hard one to gauge and almost always go over budget so stick an extra 10K somewhere or know that you could get a little loan to the same amount if really necessary that way you never need to have a panic.

How much does a kitchen extension cost

Then, once the place is built we have to deck it out. Many people fall into a bit of a trap here when their build is agreed to take them to ‘first fix’ only. First fix is when you get left with plastered walls ready and waiting to be painted, an empty room waiting for a kitchen, bathrooms to tile and plumb and doors to be hung. All of this also needs fitting, so more labour. This is why a first fix extension seems like such a good option for the balance books but in the end often ends up costing more as you addon the necessary extras towards the end. Many people that choose this first fix option end up adding all these items on, painting a room here, laying some tiles there and it often stacks up to more than if you had got an all in cost… an extension is a big space to paint yourself and be warned, painting fresh plaster needs a good 4 coats!

How much does an extension cots in London

So with that in mind, we’re going to take this rough price gauge up to the ‘I can actually live in this stage’ or, 2nd Fix. You’ve got to buy your kitchen, hard to say a price for this as it’s so dependent and appliances but let’s give it a range of £4-10K. Then maybe a downstairs loo? £400-600 (assuming the plumbing and creation has already happened). Paint (we’ll go conservative and steer clear of the top shelf brands for now) approx £200-£300. Flooring, tiles, real wood or a wood effect laminate could range, again dependent on sq meterage anywhere from £1000-£4000. Bit of marble or Quartz for your worktop? Budget for about £3-5k.

Back bi-fold doors and roof windows will range from £6-8K and a lovely over Island light fitting about £400.

All in all, if we stick to the middle of these estimates you’re looking at an average cost of around £105,000 with your cheapest option, if you’re really thrifty, around £89K.

Then you have to start thinking about your furniture… sure to save some budget for that too, it’s the most fun!

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  1. Great article! This is a really useful resource. I googled like a lunatic for weeks trying to get a rough guide like this but really struggled. Now I feel confident our choices and builder are all on track, because it does seem like a hell of a lot of money!!

    1. Hi Claire! I know – it does seem like an awful lot but when you break it all down it goes quick! It should add that value onto your home though so see it more as investing the money rather than spending it! Glad we could be of service!