1st Floor Extension

[Noel]

I viewed a house yesterday with a large ground floor extension to the rear which I'm considering making an offer on. To make it work I'd like to add a first floor extension. The extension would measure 350 sq ft and include 2 beds plus 1 or 2 en-suites (the current bathroom would need to be relocated to create access). The ground floor we'd open up the extension to create a kitchen/family room.

I've checked local planning applications and several neighbours have had similar extensions approved.

The questions I have are:

What is the difference in foundations between single and 2 storey extensions?
How long is a piece of string - HOW MUCH- ?

A mate has indicated £100 per sq ft would be a reasonable guide, dependant on the foundations.

Any advice much appreciated.

Noel

[Spudler]

First off, when was the extension built?
Depending on that factor you may be able to whip the roof off and build straight on top of the existing. £100-120/sq ft is a realistic guide if your building from scratch, it will be greatly reduced if the foundations are already up to spec/depth etc.

[Noel]

The houses a 1970's vintage and was extended in 1985. It's flat roof extension.

I'm hoping it would be an easier roof off option but knowing my luck it won't be.

[Spudler]

There's a good chance the foundations will be ok for depth (cant recall exact yr regs changed) so the next step is to dig an inspection hole the depth of the foundation, and get it inspected, then either you'll get the nod or its back to the drawing board...and that will be expensive im affraid.

[anonymous-user]

Spudler said:

There's a good chance the foundations will be ok for depth (cant recall exact yr regs changed) so the next step is to dig an inspection hole the depth of the foundation, and get it inspected, then either you'll get the nod or its back to the drawing board...and that will be expensive im affraid.

+1

[Escort2dr]

Our house was built in about 2003 - would the building regs then have ensured that the single storey bit (not an extension) would have foundations designed to suit building a first floor on top?

[Spudler]

Escort2dr said:

Our house was built in about 2003 - would the building regs then have ensured that the single storey bit (not an extension) would have foundations designed to suit building a first floor on top?

Absolutely. Even single garages that will never have another story on them have to comply the same as housing.

[MikeyT]

Foundations are now 1m x 450 I think ... (for single storey) which means that it is okay to tack on a second storey years later.

[Noel]

I've just spoken to the planning dept. who confirm the application for the extension was in 1980. Then spoke to the Building Control Officer who was of the opinion that in 1980 the fouindations are likely to have been 1m strip so should be ok.

The agent assures me the extension was done with a future 2nd storey. On that basis is the £100 per sq ft figure ok?

Edited by Noel on Monday 1st February 12:00

[herbialfa]

Depends on your locality!

London and the surrounding areas are a bit more than that.

I always tell clients £1000 per square metre is what you budget for.

However this will be way above your budget as most of the money goes into the ground!

You've already done that!