Two Storey Extension Cost

tafer2uk

My wife and I were hoping to build a small two storey extension to the rear of our property, with a small side extension. The total floor area for both comes to 63m2. The architect we employed to design the extension stated that he expected the cost to be approximately £1000m2 finished to a basic specification including kitchen, upvc double glazing, and bathroom furniture in two en-suites.

Looking around various websites and using their building tool calculators this seems a little optimistic but should be looking closer to £70k.

http://householdquotes.co.uk/cost-of-extension/

https://www.homebuilding.co.uk/


In the search for a builder which has been a struggle the two that have got back to us have both come in at £105k including VAT but excluding kitchen and bathroom fitting which we think will take the total cost closer to £115k.

I appreciate the quality of the final finish can have a big impact on the price but for the basic build what are peoples thoughts on the price quoted? I live in Yorkshire if that helps. Thanks for any input anyone has as we've never done anything like this before and so are pretty much clueless.

krey

not sure if someone can give you an answer because of the obvious-how long is a piece of a string.
If you are doing it yourself about £12-17k depending on materials used for materials for that size + the planing costs/architecht fees and other rather fixed legal fees.
Hire someone to do it for you... Depends...could be £50k ,could be £150k -depending on how badly they want to rip you off.
Bare shell building costs (materials) are around £80-£120 per sqm + everything that you put inside.

Doozergirl

The £1000 a metre figure has been banded around for well over a decade. The first time I heard it, at least. And that would be for a new build square house to a very basic specification. New builds don't attract VAT.

A square house costs less to build than a rectangular one. That costs less than a house that has protrusions. A house with rooms in the loft is cheaper per square foot than one with a loft space. A straight up and down with gable ends is easier than a house with lots of valleys. Big houses are much cheaper per metre than small ones.

There is no formula but £1000 is not only woefully out of date it forgets a whopping 20% of VAT and suggests that building is a science not an art.

It is an art.

Your architect doesn't do much in the way of building!

Furts

You are being highly selective in your link to homebuilding. It clearly states basic building at £1000-1680 then adds caveats which can increase this price - sloping ground, poor ground conditions and so on.

A one off house to current Buildings Regulations, and reasonable finish has a guide price at £1500. To equate to an extension then add VAT to this.

I suggest you have almost zero chance of engaging a builder and achieving £1000 as a metre square price. By default one can then ask why your architect is suggesting this figure. What level of competence exists here?

Think it through but equally ask how you expect to achieve two en suites and a kitchen for under £10000 - these being your figures.

tafer2uk

Thanks for the replies guys.

None of them are my figures hence the question. I may have been selective in the websites but the homebuilding website and magazine is one I subscribe to, and as a publication allegedly specialising in the field assumed it would be reasonably accurate. There is a calculator they have that asks you to put in various details and the figure it came back with was £68k including VAT.

I do plan to quiz the architect about the figures as he's a very experienced (30+ years) RIBA architect. Whilst I never thought he would be an expert on building costs, as someone himself who has done two self builds and has worked with lots of local builders I did expected him to be within £10k given he presumably would know if our extension had any issues such as sloping ground, poor ground conditions etc.

The fact that the builders both came in at a very similar price made me think something doesn't add up.

Thanks again.

Schoolworker

In based in Scotland and we have plans passed for a 2 story rear extension. Awaiting byild ing warrant at the moment hopefully in be done in 2 months and then we can see what happens. I have approached 4 builders to quote from our passed plans.
Still waiting for quotes from 2 builders. Had one high quote of £80k and other one is £55k but not sure if this include money for kitchen/bathrooms.
I thought it would be £60k and we would use some savings for contingency and of course decoration .
Time will tell but I'm learning that builders take their own time to cone back with their quote never mind if this will be started later this year.

System

with an extension, basing costs on 1k per m2 is complete folly, I'm surprised someone with that experience would give you those figures.
There are so many variables with extensions, especially 2 storey ones, slappings into existing buildings, foundations/drainage etc - what kind of information have you issued to contractors? have you given them a full set of detailed drawings and specifications, schedule of works etc?

tafer2uk

The builders have been given detailed plans, technical drawings, building regulation paperwork and structural engineers calculations. All that side has been paid for.

The price we have asked a quoted for is the basic structure finished to plaster walls. The extension requires the roof tying into the existing roof as well as the bricks being toothed.

Out of interest Schoolworker what size is your extension?

Furts

tafer2uk wrote: »

Thanks for the replies guys.

None of them are my figures hence the question. I may have been selective in the websites but the homebuilding website and magazine is one I subscribe to, and as a publication allegedly specialising in the field assumed it would be reasonably accurate. There is a calculator they have that asks you to put in various details and the figure it came back with was £68k including VAT.



Thanks again.

You come across as reluctant to accept figures given to you by experienced people, and you have now estimated your build cost at only £899+VAT per metre squared. For an extension you are stretching credibility beyond any reasonable grounds.

I said you were being selective, but this was a polite way of saying re-read the articles and stop deluding yourself.

I wish you well.

tafer2uk

Furts wrote: »

You come across as reluctant to accept figures given to you by experienced people, and you have now estimated your build cost at only £899+VAT per metre squared. For an extension you are stretching credibility beyond any reasonable grounds.

I said you were being selective, but this was a polite way of saying re-read the articles and stop deluding yourself.

I wish you well.

You call it 'deluding myself' I call it research. I 100% take on board all the comments. I am in no way saying I should be able to get the extension built at £899+ VAT per m2. I was merely trying to explain where I got the figures from. I have totally taken on board everybody's comments and based on what's been said I won't be asking for any more quotes from builders as it would be unfair to waste their time.

Best wishes to you too and I genuinely thank you for taking the time to respond as it does all help with my research into how we decide to proceed.

:beer:

Doozergirl

A really lovely builder will be able to work out what you can get for your budget. If a budget is set, then sometimes it's better to work backwards from it, addressing the list of wants and needs.

I prefer to work that way. There is nothing more frustrating than producing a quote for someone to find out that they just can't afford it.

Plan the project as a whole, paying attention to budget.