cost of 2-storey extension

[ajrobb]

I have a 2 bed end of terrace house built in 1978. It has 4.5m of garden at the side of the house adjoining the bottoms of neighbours gardens. This is crying out for an extension. The garden rises about 1.5m to the side boundary. It is on chalk downland.

Any ideas of the cost of a 2-storey extension, brick elevation under pitched concrete tile roof, 3.5m x 8.8m with a new soil stack?

How much more would it cost to build it as 3-stories with dormer window to the rear?

 

[glangri2]

How long is a piece of string?

How much of the job are you going to do yourself ?

I have embarked on a similar sized extension (7.3 x 3.2) on the end of my house. I got a quote from a local guy to build the shell, and he said £38K which I thought was extortionate seeing as that didn't include plumbing, electrics, plastering, and the whole ground floor is garage !

As it is, I am doing it myself (over a much longer period) and am aiming to come in at somewhere under the £15K mark.

As for the 3 storey question, it costs hardly anything more to specify floor joists instead of ceiling joists for the loft space (although you do loose headroom, so I am lowering the ceiling of the bedroom to compensate), and then it is a case of insulatiing the rafter space in accordance with regs.

I have gone for Veelux style windows rather than a dormer.

The big costs associated with it are going to be installing the second flight of stairs and the fire doors required.

Sorry, I haven't really helped you in terms of an overall cost have I ?

 

[freddiemercurystwin]

Around £900 per m2 per floor.

 

[noseall]

I got a quote from a local guy to build the shell, and he said £38K which I thought was extortionate

Two storey?

High end but not extortionate. You live in a fantasy world.

 

[tfish]

iv just paid 34k shell inc studwork walls and floors

i have two dormas outback too.

I was looking at around 50k all in, but the extenstion is huge i think its a foot wider than my house.

 

[ajrobb]

How much of the job are you going to do yourself?

I'd get the shell, windows, plumbing and electrics done by registered builders as I'll want to sell.

The big costs associated with it are going to be installing the second flight of stairs and the fire doors required.

Good point. I'll probably stick with just 2 storeys.

I was draining the cold tank yesterday and found the ridge is only about 7'9" above the 100mm truss joists. I'm not going to get much of a room in the roof without a massive dormer .

I suspect trusses will be cheaper than separate beams and rafters. I assume rendered block is cheaper than brick. The existing brick elevations already need re-pointing after only 32 years. I'll try and persuade the local Planning Dept that bare brick on the end wall is 'obviously unsuitable' . At the end of a cul-de-sac, it is not visible from the road.

 

[peweuk]

I'm building a 2 Storey extension at present - 10m x 5.5m.
3 Beds (all en-suite) on first floor, 2 receptions and new hallway with stairs on ground floor.

The shell is up and roof on (cut in, not trussed) and tiled with first floor joists in. Ground floor insulated (walls and floors) and plastered, and all windows in on both floors. Wiring complete on ground floor.

I've done it all on my own over the last 14 months - not full time (except for exterior rendering) and spent £12,500 so far.

First floor requires the flooring, insulation/plasterboard on external walls, studwork/plasterboard for interior walls and ceilings, wiring and en-suites installed.

My estimate is a further £7,500 to £8,000 to finish in about 3 - 4 months.

A total cost of about £20,000 and about 18 months work (not full time) seemed a much more attractive option than the £65 - £80K estimates I was given when I first looked at the project and got in some quotes.

 

[noseall]

I'm building a 2 Storey extension at present - 10m x 5.5m.
3 Beds (all en-suite) on first floor, 2 receptions and new hallway with stairs on ground floor.

The shell is up and roof on (cut in, not trussed) and tiled with first floor joists in. Ground floor insulated (walls and floors) and plastered, and all windows in on both floors. Wiring complete on ground floor.

I've done it all on my own over the last 14 months - not full time (except for exterior rendering) and spent £12,500 so far.

First floor requires the flooring, insulation/plasterboard on external walls, studwork/plasterboard for interior walls and ceilings, wiring and en-suites installed.

My estimate is a further £7,500 to £8,000 to finish in about 3 - 4 months.

A total cost of about £20,000 and about 18 months work (not full time) seemed a much more attractive option than the £65 - £80K estimates I was given when I first looked at the project and got in some quotes.

If the people around you can put up with the excruciatingly slow process then fill ya boots. I suppose if you were a real stingy tightwad and stretched the job out to ten years i bet you could probably scrounge the entire extension for free.

Most of my customers want to stay married and have a usable extension after 12 weeks.

Ho hum.

Good luck!.

 

[peweuk]

If the people around you can put up with the excruciatingly slow process then fill ya boots

The work has caused no inconvenience at all

I suppose if you were a real stingy tightwad and stretched the job out to ten years

Being stingy has nothing to do with it. I do it because I enjoy it and get satisfaction from it. I am building at my pace to accommodate the other things that I have to do - I also have a life

i bet you could probably scrounge the entire extension for free.

Not the objective - although there are so many rip-off merchants it the building trade around where I live that cost does have to be considered.

Most of my customers want to stay married

Having seen the mess that is created by some of the local tradesman, I think my wife would have left me if I'd let any of them loose on the job - and the size of the extension it would have been for a lot longer than 12 weeks - some of the initial quotes I had said to allow for up to 6 months - but that may have been said to justify their rip-off quotes

 

[noseall]

£1000 p/m per floor is an accepted approximate costing of an extension finished to a standard level.

If you think you are being ripped off because a builder wants to earn a crust, then you are either mean or living in a fantasy world.

 

[peweuk]

Living in a dream world ? hardly.

At your guide of £1000 p/m (I assume you mean p/sq.m) per floor you are suggesting you would have quoted me £110,000 - according to you for 12 weeks work. Excluding materials which cost me £20,000 that's the equivalent of £360,000 p.a.

Even for 3 guys thats £120,000 p.a per man - and I'm dreaming ???

With that sort of income I guess you never consider costs and just pay what you are asked for for everything, and to you anyone trying to get the best for their money is mean.

Anyway - this is now going off the original posters topic - so enough said.

 

[freddiemercurystwin]

peweuk, £1000 per m2 per floor is a rough guide for having the lot built including all professional fees, trades and finishes whether you agree or do not. It is a guide used in the industry and is quoted throughout the web when people look for a rough price. Comparing it to a completely self built project over many months is irrelevant.

 

[hotrod]

some of the local tradesman I think my wife would have left me if I'd let any of them loose on the job

Who could blame her? The majority of tradesmen are well toned from the manual labour that keeps them in tip top condition physically. I have heard many a tale of the bored housewife fed up of waiting for "stingy weedy hubby" to finish the diy and taking a shine to a bit of "rough and ready".

 

[glangri2]

£1000 p/m per floor is an accepted approximate costing of an extension finished to a standard level.

That is fair enough, but for DIY enthusiasts, who want to do a large portion of the work themeselves, what would be an accepted approximate costing p/m per floor for having just the shell built.

If I wanted a 2 storey 40msq shell built, (No windows, No electrics, No plumbing, No plastering, no internal floor or ceiling finishing) how much less would it be likely to cost p/m?

 

[garyo]

I'm doing a single storey front extension at the moment, doing 100% of the work myself, and I'll be lucky to get it in below £450 per m2.

Mine is only 8 square metres, and there are economies of scale the bigger that you go (footings/walls/UPVC being expensive, perimeter to area ratio kind of stuff, planning and building control fees...)

Spending your own free time rather than spending money for a builder is an interesting thing to ponder. You're effectively taking a second job on top of your full time career, but rather than just benefiting from a builders equivalent take home pay, you're also avoiding his tax, NI, employers NI, cost of sale, profit margin, insurance premiums, advertising, yada yada. So it's not really a level playing field, not really a fair comparison, and not at all scalable

Gary