How Much Does A Kitchen 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 a terrace street in London? Preferably on a Victorian semi I’m guessing? Well read on…

First just a quick caveat, these figures are our estimates at the time of publishing, Brexit and Covid are effecting costs, mostly wood and concrete at the moment. Also all prices mentioned are London centric, things may well be cheaper elsewhere!

For this rough estimate though, we’re going to assume you have middle ground taste in finishes, kitchens and bathrooms with the odd splurge of luxury finish to bring the whole lot up a level and a few eBay and Facebook Marketplace finds thrown in for good measure and character. 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 terraced houses don’t have… This ‘paperwork’ as we call it is going to come in at around £5-9K mostly dependent on your chosen architect.

It’s at this time you’ll also want to factor in your Interior Design – you may think this is early but it makes total sense to start now. Interior designers can work with your architect to ensure that your final design and living space is every inch perfection. How will those wall sconces go in if there’s no wiring ready for them? How will you know where to put plug sockets if you don’t know what furniture and lighting plans you’re going with? What finishes will you be using? And so on…

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 for ease here, 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 panic or compromise. During this time you’ll need the steels that the structural calculations company have said are necessary. Usually these are to support the original back wall of the house and also to support the new back wall above the back doors. There may be more if for example, you’re removing a chimney breast to make way for flush kitchen units. Steels you can budget for around £4,000.

Then, once the place is built we have to deck it out. By this point you will have made all your major interior design decisions and paint, flooring and bathroom items will be coming into play.

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, plumbing to attach and doors to be hung. All of which needs fitting, so more labour. This is why a first fix extension seems like such a good option for the bank balance but in the end, often costs more as you add on the necessary extras towards the end, not to mention the possibility of having to find decorators and kitchen fitters to continue the job. Many choose this first fix option with the intention of finishing off a lot of the decorating themselves, which is great if you have the time but often you don’t, leaving you with a room painted here, some tiles laid there, someone called in for this, a balls up with that and often it can end up costing more (certainly taking a lot more time) than if you had got an all in cost (which can seem scary a scary figure at first but often when you break it down, makes sense)… an extension is a big space to paint yourself and be warned, painting fresh plaster needs a good 4 coats!

So with that in mind, we’re going to take this rough price gauge up to the ‘I can actually live in the house now stage’ or, in trade terms ‘2nd Fix’. You’ve got to buy your kitchen, hard to say a price for this as it’s so dependent on tastes, providers and appliances but let’s give it a range of £7-15K, £7 being your Wickes kitchen with some extra drawer inserts and home brand appliances and £15 + being your MasterClasses and branded appliances. Then maybe a downstairs loo to go under the stairs? £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 for a lovely over Island light fitting or two put by about £500.

All in all, if we stick to the middle of these estimates you’re looking at an average cost of around £111,000 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! And, it’s where we really go into our element.

If you’re planning an extension or renovation and want advise or interior design services LFF Studio offers both in person appointments and 1:1 Video consultations for advise as well as a full service design studio. We’d love to chat about your project! Get in touch below or join our free Facebook Group – Ain’t nobody like a home body, where Lu checks in daily to answer any questions you may have about interiors or renovation!


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