Did your extension cost anything like the 2k per m square rule of thumb?

[Grobagsforever]

Got planning permission for a 27 m square extension (over 2 stories it's 27m Square in total). So in theory even taking into south east extra and allowing 3k per m square it will come in under 100k, but no one seems to pay that little round here.

So before I go through the quotes am curious to know if yours was anything close to the guide??

Yes ours was (2 years ago) although VAT on top, but it depends what you are having done and your quote includes.

Where did you get the £2k per m2 figure from? Not being arsey, I've been a quantity surveyor for 30 years and just want to give you a complete answer

We are south east and have a single storey extension planned. 6 by 4. Our quotes have ranged from £60k to £80k not including kitchen or VAT.
We have one quote of £35k to do just the basic build from a builder that's had a job cancelled so has availability ASAP.

@Tomorrowisanewday seems to be the generally accepted internet wisdom and also my architect

Thanks Minne!

As a pp says, quites can vary enormously from say a pure build cost, to a quote for a more finished / high spec job.

Our quote included some electrics done although we paid to upgrade from basic white plug sockets etc (it didnt include any electrics at all for the kitchen as it didn't include kitchen / fitting), plumbing for bathroom but not fittings or installation. It included windows but we paid on top for bi-folds, radiators, external / internal doors, and obviously kitchen, bathrooms, fittings, flooring, decoration etc.

13.5sqm per room for an extension seems very small? ... are you sure that's the size? ..surely that's only approx 16ft by 12ft room? ... even double to that fit one room in each floor and I'd question if the extension is even worth doing? ... I'd want it to be less than £100K too!

Yes, 6 years ago worked out at £1800 psm not including the kitchen

Think mine worked out at around £1,400 per sq m (excluding the vat) four years ago, just for the build including wiring, heating and for fitting a new bathroom and an en suite (we provided the bath/shower loos etc). That was for a three-storey extension (so approx 30sq m per storey) with the top area being a continuation of the “loft” room. I am told the footings and roof are big costs so I guess with three storeys, we got optimum bang for our buck, so to speak. Incidentally our quotes varied enormously: £79; two at £120k and one at £250k. We picked the £120k.

£79k not £79!!

@shouldbeworking.. yes the measurements on the downstairs are 4.57 * 3, so 13.71 m squared. It's to replace a conservatory and add a double room on top. Not massive no, but will create a lovely open plan kitchen diner instead of dining in freezing conservatory and a much needed 4th bedroom.

Going a bit bigger doesn’t increase costs much. I would make it worth the upheaval. Ours was in excess of £2000
Pm2, but it’s very high end finish.

I’m SE and we had a single storey extension last year and it came in at about £1350 per sq m , that included a pitched roof with 2 velux windows , electrics , plastering . The knock through and fairly complicated steel was 3k ( included in the sq m cost) . It was cheap because we found a lovely but extremely dodgy builder , what should have been a straight forward job took months to complete and eventually we outsourced the knock through to a different company and organised our own plasterer . That said it’s been built to a great standard and we are very happy with it . The builder , last time I heard , is now an estate agent .

We are currently going through this now. South east also. It will cost us £140k to get it built for 50 m2 but we are doing some bits ourselves to save money. Good builder has worked for us on a past house. Alot of our quotes came in higher ( not unexpected as it's a more complicated build) our architect told us to budget £3k pm2 to complete.

This does include £3k on bat surveillance.

Our single storey extension 5 years ago was in significant excess of £2k/m^2. There were reasons for that, we had to pick special bricks to match and we had to have handmade wooden windows. But we paid about £55k for a 3m*5.5m extension with vaulted ceiling, purely for the build cost - so, to plastered walls, electrics and heating. Everything else (flooring, decorating, kitchen) was ok top

Paid £2037 per square metre for the build and electrics. Ground floor only and included 5m sliders, underfloor heating and several Velux windows. Spent more on kitchen and fitting out what became a utility.

Brilliant quality and in hindsight think we got a very good deal. On aspect was we were not in a hurry so meant the builder had us as an awaiting order which suited him

Gosh that all seems incredibly expensive OP. We are just at the beginning of this process, with an architect currently doing some drawings but if it's going to be £3k/sqm there's no way we'll go ahead with it. We're not in the SE but still somewhere with very high demand for builders.

@bubbles - I can't. Planning permission for something larger got refused :-(

@flora that sounds incredibly stressful, glad it's all ok now!!

@slighty, thanks that's really useful, but what on Earth is bat surveillance??

Thanks @raindrops!

Sounds like a great deal @marie!

@pepp- the south east IS significantly more expensive than everywhere else though and my part is especially expensive:-(

We extended by 5m x 5m in London. The full cost including new kitchen, glass sliding doors, new window frames, flooring, etc etc etc was £100k. We didn’t go for things like underfloor heating etc which would have cost more.