How much does a UK house extension really cost? 

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The cheapest way I’ve found to get the cost down is to talk yourself out of the idea 😊

As a retired project manager, 8 years out, I found your extention costings extremely useful in order to bring me up to date on current material costs for 22-23. I am still asked to do work and to give advice, so costwise, your advice was first class, uncomplicated and suitably brief. I commend you sir. John Roake

Thanks for taking the time to do that breakdown of costs - very useful. And I'm glad you mentioned the costing of your own time. The trade off is your eye is always on the ball. As some of your earlier posters mentioned, Building Regs change all the time, adding to your costs. The great thing about being involved is that it (usually!) gets done how you want it. I'm 67 now and have got 2 projects on the go for two of my sons. I think these will be my last Particularly as they bought me the latest 1:24 scale Spitfire from Airfix for Xmas!

Eventhought I am not planning for the extension, the amount of knowledge and insight is amazing.

We're planning our extension at the moment; your breakdown is excellent and has put my mind at rest that my finger in the air costs are about right. Looking forward to your guidance on trades - normally I do everything myself but for speed and sheer amount of effort I'm considering getting blockwork and the like done by someone.

Thanks for posting such a detailed spreadsheet breakdown of the whole process. It's very open and generous of you to share your costs and experiences of the build. Very helpful and very interesting. I do feel like I have a sense of investment having lived through your last four houses though now! All the best for 2023.

Very,very useful; I've forwarded this to my brother-in-law who is thinking of extending their 1930s semi in South Liverpool. Appreciate the time and generosity of sharing. Tony

I’ve been waiting for some time for such a detailed and honest appraisal video. Absolutely fantastic. Subscribed

Coming from a Engineering background and having worked on construction projects for over 18yrs now, it's good to see someone breaking down a project on a residential extension. I've done extensions and I would have at around £96k from information and sizes off your plans. And that would be making a modest 10 to 12% I reckon. We only work to specification and above. Looks a nice job, well done. Regards

It has been a great following your journey with this project. Looking forward to the next one. Well done👍🏻

Really useful information. Thanks for taking the time to go through it all. Great job 👍🏼

Thank you for taking your time and sharing this with the public, top man 👍🏻

I did my own extension 4 years ago and came out at £26,000 with kitchen. That was 3m x 8m with bifolds toilet and utility. Bare in mind I only had a brickie, electrician and plasterer. Everything else I done myself including making sure building standards were met. But I've done projects in the past with work. It's not easy especially working full time as well but it's definitely worth the effort.

This was such a great video, from clarity to quality of information shared. Wow, super well done , subscribed !

I've only come across your channel yesterday but you are definitely one of my favourite content creators! So knowledgeable and just and all around nice guy!

Great video, really informative. We have an old (Victorian) stone-built detached house, to which we've done extensive renovations that have so far taken us 21 years, but we've done everything ourselves, except for some structural steelwork which the house needed in the cellars. One of the jobs we did was a full cellar restoration after the steelwork had been installed, this was a huge task as the cellars are full height rooms which cover the entire house footprint. I reckon we completed the work for about one tenth the cost of what it would have been if we had used contractors to do the same job, plus we probably got a higher standard of finish and everything was exactly how we wanted it. It is very hared work and very time-consuming, but you can't beat doing it yourself if you have the skills and the inclination

Most insightful of all the building videos I've watched, so many about the different ways to build but no one has broken in down by doing it yourself as opposed to asking the builder. thank you

Amazing, thank you so much! This is unbelievably useful as we're just starting out and trying to get as much info as possible. Much appreciated 🙏🏼

Excellent video on pricing a build and what it would deliver…really important way to break it down! Thank you for sharing!!

Great video. I’m a builder of 20+ years running my own business and even after all that time pricing jobs is my nemesis. I hate it with a passion, each job is so different and intricate that guide line costs per m2 are sometimes very vague and I certainly wouldn’t quote based on them alone. I have always considered it as gambling really. You can so easily come a cropper by not quoting enough and nothing is more soul destroying and financially crippling like under quoting and working for free, especially as it’s a very hard job both mentally and physically. One thing I would add is that I’ve deliberately not quoted for twice as many jobs as I’ve actually quoted for. This is because the job is comprised in some way e.g poor access, lack of room to operate, awkward neighbours etc. The number 1 reason though is because I’ve not gotten good vibes from the client. Too abrupt/rude, disorganised, unprepared for the realities of having your home turned upside down temporarily. It’s very much a two way thing. You must trust me to dismantle and rebuild the most expensive asset you will likely ever own and I have to trust you’re going to pay me for my work and be able to adapt and understand when things don’t go to plan i.e unforeseen problems and changes. As a final thought, most of the very best tradesman are the best because they do what they do best and that’s create actual real 3 dimensional objects and installations. That means they usually, like myself, hate doing paperwork and quoting otherwise they would just get a cushty office job in the warm and dry without breaking their back for what seems at times like not enough money. I’ll stop whingeing now 😂

Excellent video and breakdown of costs involved in this particular build. Every project is different and usually throws up its own issues.

Really useful, and many thanks for all your other videos. I'm about to start an extension, and this information is really valuable.

Wow I comprehended all of that! Your itemizing is really useful template for putting projects together to consider and maybe stagger stages of development to budget. Thanks 😊

Great video and really interesting. I'm on both sides of this, having been a joiner for 28 years and lecturing and working in construction. I am now halfway through an big extension at home that started pre COVID and due to spiralling materials costs, lockdown etc is still ongoing. As a self builder I have seen prices spiral during and post COVID... I wouldn't put any stead in pre 2019 prices...it's almost like a different era... In the last 4 months I have seen Aluminium window prices go up almost 40%. In the Swindon area building is going on at a staggering rate and materials demand and prices are definitely reflected in that... Don't even get me started on how expensive timber is. Our extension is 2 storey and single storey...roughly 60m2 . My original costings in 2020 using Spons (worth the purchase price as this really will give you a very accurate pricing structure) was £90k Inc £10k pc sum for kitchen and £5k for ensuite...this is materials and labour. I think realistically now we will be lucky if we keep it under £110k and I have done all the work...( Foundations with a mate who is a ground worker) all blockwork with another friend who is a bricky...so very much mates rates. All carpentry..roofing ..floors...concreting etc all me. Most of the plumbing fit out will be me but electrical work will be contracted out. Ours is what I would describe as High end build ( anthracite aluminium windows, Canadian cedar cladding, bespoke kitchen etc) so was always going to be on the high side but at the moment if you work on £2k per M2 you will give yourself some wiggle room. If your builder quotes £1k per M2 and doesn't itemise their quote then watch the extras roll in....or watch them bail. There are no 2 ways about it building is expensive at the moment and finding reputable builders is going to cost so don't kid yourself it will be cheap. One of the biggest single expenses is skips...holy cow waste removal has gone up over the years. I should point out we had 4 quotes pre COVID.... They ranged from £68k plus vat for just a water tight shell.. No kitchen, bathroom or floors / internal walls ( I was going to do those) to .. £160k plus Vat. ( With no PC sum for kitchen or en suite) none of the quotes included plans/architects fees, site surveys etc as I did all those myself. I think realistically if we handed our build to a good builder from the start and kept the same spec we would be looking at around £150-160k plus VAT... At the moment I am still on target for a £90k Inc vat spend but that includes everything including drive, gates and landscaping....so not just the 60m2... But remember I have done nearly all the work myself so no builders/ labour costs..but the quality is there it just takes time. ... It's the eternal triangle...Time, cost, quality.... Thanks for sharing your costs....all too often you see people running into financial difficulties when building ..relying on quotes and then looking at final figures trying to work out how they are 20% over quoted... Now imagine our situation where prices have literally doubled between pre COVID and post COVID.. god knows what we would have done if I hadn't been in trade. Take heed people ..never go for the lowest quote and always get references with pictures and testimonials you can follow up.

Thanks Andy, this was very interesting & meticulous. I really don’t know how you found enough time to do it all, then I read on another comment you had a day job too!! Amazing, well done to both of you 🙌👏👏👏👏.

Cheers Andy, very nice of you to share. Great job all around on the extension

thanks fella, i think this kind of vid gives a lot of clarity for how things are in the trade at the moment, i'm a 1 - 2 man band , but i used to work on major construction sites. its been hard to express the benefit of a well managed installaion/project. you have demonstrated here why it is worthwhile paying for a bit of managment experience in the pot.....You have this from previous projects but, thank you for opening peoples eyes to how much co-ordination goes into what is a beautiful extension.

Good thing I can do the planning myself and also build it myself, all I would need to pay for would be materials and the groundwork! It is extremely beneficial to acquire construction skills in your lifetime!

Been working in the trades my whole life and would agree with everything you said. We also much prefer working for self managed builds if the client knows what there doing. Generally less stressful lol!

Thanks for this, we’re about to get ready for an 8x3m kitchen extension, a pretty big kitchen. I’m grateful for these costings

Thanks for this Andy, very instructive, planning an extension myself in the near future so this is very useful ahead of getting any quotes !

Well done mate. We mainly did large commercial/corporate jobs when I was still in it but did do a few small builds and extensions too. I just dug out my last set of builders bibles from 2009. Its m2 averages are £750 for basic going up to £980 for high spec (stone, thermal etc). We had our own formula that fell in between at the time. My earliest edition (early 00's), from £350 m2! Gone a bit crazy eh? Again though, excellent video and grand job on the extension.👍

Thank you so much for this. We had virtually given up on the idea of proceeding with our 15sqm garden room (even having spent £6k on planning and drawings) after being given an estimate of £110k inc VAT for an empty shell by a member of the "Federation of Master Builders". That is £7200/sqm! It is time to start searching again for a builder that we can trust. There is a public need for information like this. Thanks again.

What an absolutely fantastic video - can't believe I found this amount of real knowledge/experience by accident... like/subscribed and looking forward to the next one 👍👍

I find it inspiring watching this and all your other vids Ive a small (very small)channel I am a plasterer in York I watch your channel to see how it should be done RU-vid that is I always try to give value and your channel really does show how it should be done. Cheers Alan

Very thorough breakdown of costings but, only what I'd expect from someone so meticulous and tidy.... well done to you both. HNY.

So I built a 30m2 kitchen-diner extension myself (which is very similar to yours). Three new walls, built 8m out the back of the property. Brickie and his dad (who did ground working) did the foundations, brickwork, got a solid flooring contractor in, cleared about 40 tonnes of spoil (sloping site) and sorted the scaffolding for £13k. I bought the bricks, blocks and insulation. I then did pretty much everything else myself (except the Part P wiring), including the roof (pitched with hip) windows, doors, plumbing and boarding the ceiling and walls. Paid a plaster £800 for a skim, and an electrician £600 for the Part P stuff (I bought all the lights, sockets and distribution board). Plans cost a few hundred quid and the local authority forgot to charge for the building inspection. Whole thing came in at under £30k. Then I blew over £20k on a Wren kitchen sadly. Lots of quartz!

Fantastic video. Great honest information, clearly presented.

I have been contemplating extending my house, looks like it’s achievable. Thanks for sharing

Great video as always. Also need to be mindful of the extra costs when using trades. They always find some issue that will inflate the quote.

I have recently completed an extension which included an outbuilding (no soundproofing concerns) but went through a similar process opting for it to be within permitted development too. The 2.5 M maximum height was a little open for debate when researching especially on slopped gardens. Unlike you, we had a difficult builder and although I had expected him to be here for a significant portion, he would send a couple of his guys over each day with little supervision. I ended up having to project manage making sure materials were ordered on time, sequencing deliveries and trades people so that work would progress. As I was losing confidence with him, I was forced to check and verify that everything was being done to the right standard in terms of building regs, including the checking that the correct size steel was used. I now know that this builder did not know how to price a job or made significant assumptions on costs including labour. We had a fixed sum contract in place which detailed every requirement he needed to meet and checked with him multiple times that if we was confident with what he quoted. He didn't finish the job and I had to complete a substantial amount myself as well as bringing trades (front drive, rear patio, guttering, fascias, internal doors, some tiling, fence panels, coping stones and so on). After all this and having to pay more for others to come and finish jobs, the total price per SQM (£1190) was fairly close to what you've achieved. We are in the Midlands so in terms of price could be considered somewhere in the middle. The above doesn't include the external landscaping work which came in at around £83 p/SQM. Year (s) 2019-2020 Overall building extension (including redeveloping existing rooms) size 114SQM and external hard landscaping around 300SQM. All done now and have very similar spreadsheet with every little item detailed (I thought no one else will do that, lol). Well done on keeping the kitchen costs so low too. Hopefully this may help others who are in the early stages of their journey. Cheers and GOD BLESS.

A brilliant video - super clear and has vindicated our recent decision to self manage!

Great work Andy..Well done to the whole family, love the Tape measures scattered around in shot. (luv mine)

Great video, which couldn’t have come at a more appropriate time as we start our own extension journey! We have witnessed several builder nightmares and hope we can avoid this happening to us. Would be interested to know where you got your kitchen quote from? Well done and look forward to seeing further videos.

Andy this was a great video . I do this also for a living and Builders are absolutely ripping it these days. No question raw materials are more expensive than previously but when you breakdown the costs properly it’s pure greed . Your man that said he couldn’t buy the materials for 64k will be someone who doesn’t know how to cost a job so he just over inflated to cover his incompetence. Keep up the good videos they’re excellent .

Very helpful to understand what cost could be, and I think you have done it for a very good price!

Excellent video and really helpful. It's amazing the variance on those quotes, and definitely pays to be informed and shop around eh

Wow that's really useful, a great video thank you, my extension and renovation work starts next month, my costs are coming in around £70k, but that includes total renovation of the downstairs. but ya, this is so stressful, I can't tell you, not for the faint hearted, I hate stress. if you don't like stress, don't do this! It has certainly put me off doing such a large project again, and we've not even started yet.

Just finished a double story 5x4.5m extension and it’s cost £40k. Project managed it ourselves and sourced all the trades. Builders were quoting double and more to do the entire build, so we’ve saved a fortune.

this is really, very very good information!! Thanks for your efforts here.

Thank you for creating this video! You have provided very helpful information.

I had the sales guy from Beers the building merchants in today as Im looking to build a 3mx8m second storey extension. For the blocks, concrete and cement, ive been quoted just under 1500 quid. Glazing will be well under 2k for 3 french doors and juliet glass rails. These prices are more realistic as were building it ourselves over a few months. Im seeing friends getting silly quotes of 75k for the same size. Ill be bringing mine in between 15 - 20k. Great video

Very thorough Andy thank you. Getting any decent tradesmen/company to quote and do a job is a nightmare. And i can quite understand why your other building company only does commercial stuff now and there are a variety of reasons why. Im really impressed with your spreadsheet skills 😊 by the why. There is another issue thats a modern day thing, so as we are a simular age. We grew up with people who do things and we learnt from them. Sadly a large proportion of people cant put a plug on. And if it cant be bought from amazon (expecting perfection from a box) they struggle. Just different times thats all. I recently bought a new washing machine and some younger people were amazed that it was plumbed in and working within half n hour, not a difficult job at all we both know, but you get the picture. Thank Andy great vids as always.

Great Video Andy, Great info and your house looks fab. Happy New Year and I look forward to your 2023 videos

Best break down ever on you tube. Very much appreciated ❤ thanks a lot.

Proper product placement with no less than three measuring tapes in the kitchen diner shots 👏

Hey boss, in the states what you did is called an "Addition" that's the common slang. I just finished a 4,000 sq ft addition to my existing 1500 sq ft home here in the states at the exact same time as you. Stated documenting it on my YT channel and got lost in the details. Phenomenal build on yours as always. Wouldnt expect anything different from you. Been with you since the beginning. Bring back "Measuring Up!!!" haha

About to extend our kitchen so very helpful, thanks

Really good level of detail I look forward to watching your other videos. We’ve been trying to figure out how much an extension would cost and had mixed results from speaking around.

Professional builders do not quote per SQM every job is different, access, ground conditions, materials, bi-folds, lanterns, structural work & services can vary price. For estimating & budgeting a ballpark of 2.5/3k per SQM would be quoted to a client in SE UK in early 2023, once client seems keen a full detailed quote would be done that could take several days to complete! Unfortunately, material prices at the highest ever brick are £1.20 + blocks £2.50+ plasterboard £10+ as well as other costs of running a building company fuel etc. Time a builder spends on site is not the only part of the job collection of materials, ordering, quoting, and liaising with clients many of us work 60-plus hours a week! Unfortunately, many clients don't see this & think they're getting ripped off, there are many rip-offs & cowboys around but just as many decent contractors get tarred with the same brush. Been a contractor 24 years & only working on recommendations & tell my clients I won't be the cheapest or most expensive but will do best job possible for a fair price.

Random number generator! LOL. Well done, Andy. I would call it a renovation with an addition. And just for folks watching, the cost per square foot or meter, think about what is included in the renovation and/or addition. If you add one bedroom, vs one bathroom or kitchen, you have the two extremes, considering what is to be included in the new space. A bedroom would be the simplest sort of addition, with the least expensive components, vs a bathroom or kitchen that would include millwork, fixtures, plumbing, and more complex electrical considerations. So many things to consider, so that is why throwing a cost per square whatever at a project is a dangerous attempt at budgeting. I proper design should be done first and then get bids or quotes from reputable contractors or subcontractors. I have been in the design business for over 30 years and built many new homes as well as done many a renovation and addition. Don't get caught without a plan folks, and be sure that you make as many notes on those plans as you can, so you don't have contractors coming back to you with their hands out.

awesome detail and explanation. Thanks for sharing!

Thanks for the video Andy,this could be really useful for people contemplating this type of extension.👍👍

This must have taken a lot of work. Thanks Andy. Good job you are a complete control freak, looks like it's saved you about a hundred grand! Well done to you and Mrs Mac👏🏼

Did you look at sip panels for the walls? They can be prefabricated and put up in days compared to the traditional wet trades. The thermal values are excellent and can be really cost effective.

I used to do loads of extensions in gosforth and jesmond areas, these are the sort of areas good builders can get a good name for themselves, good video mate

Thanks for this video! I’m thinking about building my own extension and have been following your build. I’ve just subscribed, keep up the great work. 👍👏👏👏

In the U.S. we primarily use 'addition' to describe any new added space, but extension also works.

I managed a 7 meter dee and 8 m wide wall to wall extension, bedroom on first floor and a dormer in about £140000. I think I need another £20-30000 to now fully fit it out. It has ufh and tiling on all three floors, no radiators and new wiring. I achieved it by doing the work myself with my father and hiring two day labourers who did the grunt work. The only thing I outsourced to contractors was brickwork, skimming and the hot water cylinder installation and the electric fuse board. I did pipe work and electrics myself. Tiling myself. Etc etc. it’s taken two years of my life and probably another 6 months before I can get back to other stuff. But I have thoroughly enjoyed it. I won’t ever do it again though. 😂

Thank you! Very very helpful. Much appreciate a very detailed breakdown to give me a better idea on what to expect.

Congratulations, that was a great achievement, great informative video.

Biggest gripe I have is contractors who would rather grossly overprice a job instead of saying they’re to busy or not interested.

I clicked on this with very low expectations but I am now subscribed. Good job!

Well this gives me some hope, as I start our 90m2 extension in Consett. Great video.

Just finished our kitchen extension (3m x 2.4m),Including upgrading kitchen units and new quartz worktop and semi solid oak floor. I had a brickie, plasterer, joiner and plumber in. I did the wiring myself and I supplied all materials. I did all groundwork myself. Including planning, building control, architect and structural engineer fees, the total cost was £14500. Our expected cost was £15k.

Love the product placement! Reminds me I could do with a tape measure!😂

Excellent and helpful. It put me off doing it but I understand the process much better. Demystification. Thanks

Great video mate. Well explained. Many thanks

Best advice I’ll give to anyone living in England, try and find some Polish or non-English tradesmen or builders, they’ll do just as a good job at two thirds of the price.

Excellent as always. Been looking forward to this one. Our wrap around single storey extension project is due to start in May. I am dreading our re-quote a month before. We got our price in feb 21 (edit Feb 22 sorry) and then booked our preferred builder based on reputation and then chose to wait over a year to get them. In terms of cost comparison, the 3 quotes we got were all within 10k for a circa 90k project and the average was bang on what the architect guessed prior to gaining quotations. I should add our project includes a complete ground floor rework (remove all walls and create new rooms), large bifold, large glass feature window and 2 triple velux roof windows in a pitched roof plus move of an existing window and sill adjustment plus plumbing and electrics (we just need to source flooring, kitchen and final decoration. I am also wondering what effect the new building regs will have on the re-quote: We didn't get regs done until after the change so the walls have changed for example, cavity now wider etc, so assumed more insulation. I would love to do some of the project management but just don't have etc time with work or other family commitments. Am tempted to fit the kitchen myself though and will be doing some built in cupboard work.

Excellent vid and whole series.

What a brilliant video. Great honestly well delivered.

My wife and I bought just under an acre of land for the purpose of eventually building our own home. We appointed an architect. He asked if you could delay building this home for atleast 12 months because building materials had gone up by at least 20%

That’s crazy. I thought I could do a nice diy little extension for under 20 grand! I’d be doing brickwork myself

Thanks for that, a great breakdown on the costs.

Great video & break-down of your amazing extension... thank-you. Don't take this the wrong way... but - you're an 'Anorak' of the best kind - you have all the detail, keep records & present it really well. I'm in the electrical trade & was like a 'nodding dog' for almost all of it. Also... it's fab it how you can show folks how to silcone a shower one day then build an extension the next - bonkers! LOL Well done mate... Anyway, I don't want to give you too much praise!

Great video, very helpful. Always best to get 3-5 quotes. A friend of mine saved £34,000 in total on a high quality extension just by getting different quotes. The ironic thing was, the expensive builders called back a month later asking if they've found a builder for the project. One reduced his original quote by £23,000 and another by £32,000. Shocking how much builders inflate the price.

Fascinating as ever. I guess my #1 question is - if you were me, and therefore totally not a DIY person or skilled in any relevant trade, what would that have done to the costs? Do you know how much time/money a builder would have charged for the hours they would have needed? I'm assuming you are well aware how long it should have taken. I once tried to "manage" a significant refurb and the disagreements at the tail end with the builder were extremely stressful and unpleasant so I appreciate the fantastic job you did here - amazing!

We are getting quotes for a double story extension 50m2 x2 and a single story at the back of about 25m2 but also a total refurb of the old kitchen. I find your breakdown of cost very helpful. We are in the Wickham area. Quotes in the first instant ranged from 54k up to 120k.

Thanks for sharing and taking the time to break it down in such detail .. very helpful .. thank you ..

Andy, thanks for being so well organised as to be able to provide that info! I guess you sacrificed the opportunity of a fair amount of income to be able to work on the house yourself. Did I miss you saying how long it all took? All the best

It has been inspirational to follow and well done, you are an absolute gent! One question: If you were to include your own labour,, how many hours did you commit to the project and if you were to pay yourself an average hourly rate, how much would that have cost?

Great video explaining the costs.

Great financial analysis there. Top job!

Excellent video, I'm glad I stumbled across this (Subscribed). I've been refurbishing our home for some time now, doing all the work myself. We still have a single story kitchen diner extension that we want to build on the back and were going to leave this bit for a professional builder but with costs of things the way they are now, this has really inspired me to look into managing the build myself. I have most of the tools that I'd need already for the bits that I'd do. One question though. I'd love to get my hands on your Excel template for costs that I could customise. Have you considered sharing this? Good work on this.

I knew a guy who built a wooden boat. When we asked how much it cost he said, “I took all the receipts, organized them and put them in a binder as I went along. When I was done I sat down, opened the binder, then immediately closed it and threw it in the trash. I enjoy the boat too much to know how much I paid for it.”

An excellent comprehensive guide!

Excellent!!! Yep roof and the windows doors were slightly over.

I live in a high cost area (thanks London) so I think my single story extension, wetroom, new bathroom, garden studio, refurb kitchen and total redecoration of the whole house as well as painting the exterior was around half what people in my neck of wood say. I did do a lot of upcycling like used one door as the back door (no bi-folds) and the other one went into the studio, and 2 second hand solid oak doors kitchens to make mine. I could have done it a lot cheaper, but I did splash out in certain areas like ceramic flooring and taps. Not sure I want to ever see a heat gun (spindles are a nightmare) or a paint roller again.