How much to budget for a extension?

m0t

I have a chalet bungalow style house so 2 rooms on the first floor and everything else on the ground floor, the ground floor then being wider than the first floor with the roof sloping down.

A lot of houses around us have extended the first floor so it's as wide as the ground floor by removing the bottom bit of the roof and building a wooden box which makes the building cube shaped. Depending on how much of the space they take up it adds about 20 square meters and allows a bathroom to be placed upstairs.

What I can't work out is how much this should cost. People seem to quote £2k per square metre but I can't work out how realistic this is for what we need doing.

For comparison a house a couple of roads away has had the shell done in about 2 weeks and I would have thought this would be cheaper than something downstairs that requires groundwork and foundations.

What's the best way to get an idea of the cost of this? I'm really looking for the cost of a partitioned extension that's complete externally but a shell internally.

cattie

I think it's best that you state what area you're in as something here down south is going to cost a lot more than a similar job up North.

Doozergirl

You want what is called a dormer extension.

It would be cheaper than something with foundations, yes, but you're talking about quite an intensive amount of work in a small area.

The shells on anything happen very quickly, it then slows down when you're dealing with the detail.

It's really hard to even guess at a price without seeing the place.