Easy way of calculating house extension costs?

ali_hooch

Hi Im hoping to have an extension of 39' x 14, can anyone tell me roughly what price we would be paying in cambs area for single story and if this included pipe work, electrics roof, doors etc? Im out of touch lol. thanks ali

Cal_Retired

I am planning a bedroom/bathroom extension 3,5m x 7m single story, sloping roof - I can see others have listed approximate costs per sq metre for "brick" build - are there any other cheaper methods of constructions, maybe lighter so the groundworks don't have to be so deep/big -

does anyone make prefabricated walls? Or methods such as Hempcrete which seem to be lighter,
also seen a house made of compressed plastic panels, developed by Swansea-based Affresol.

And will a green roof be cheaper than welsh slate?
Thanks for any help you can give,

lincroft1710

Cal_Retired wrote: »

I am planning a bedroom/bathroom extension 3,5m x 7m single story, sloping roof - I can see others have listed approximate costs per sq metre for "brick" build - are there any other cheaper methods of constructions, maybe lighter so the groundworks don't have to be so deep/big -

does anyone make prefabricated walls? Or methods such as Hempcrete which seem to be lighter,
also seen a house made of compressed plastic panels, developed by Swansea-based Affresol.

And will a green roof be cheaper than welsh slate?
Thanks for any help you can give,

An extension providing additional living accommodation has to have building regulations approval. Unless the construction is 2 brick/block walls thick with insulation between the walls, with a suitably insulated roof, you're unlikely to get BR approval.

Foundations usually have to be deep enough to support a 2 storey extension.

It is possible to put up an extension using inferior or non traditional construction, but the usage would probably be limited to garden room or conservatory.

Talk to your local building control officer. He/she will soon tell you what you can and can't do.

free1000

I'm looking at the possibility of adding a second story to a barn that is approx 70' long by 16'6 wide.

The current roof is tiled so I expect that the existing tiles could be reused. Not sure about the existing beams, but they have nice character so it would be good to reuse them for the roof after its been raised.

So I suppose this would require raising the existing walls by a 1-1.5 metres, putting in a floor and then knocking out the existing walls downstairs in a number of places. Installing a couple of stairwells and so on.

What would be the rule of thumb for estimating the cost of this today? For the structural work. Is £1200 per square meter reasonable?