Extensions Question

Idea of cost for second floor extension only

hi, I am moving into a property which has a first floor extension and planning permission for a bathroom on the second floor which is yet to be completed

what would the rough cost be for building this second foor bathroom please? size is approx 3.2m x 2.5m, pitched tiled roof, block with 50mm insulation cavity, rendered exterior

I appreciate there are many criteria, but any rough ideas would be great

many thanks

8 Answers

Best Answer

average price for this would bee 9k to 11k but not sure if the foundations would be strong enough to build on existing foundations you would need to find if the foundations are deep enough through a structural engineeri noticed you have planning permission so foundations may be ok to build on

Answered 14th Mar 2011

Finebuild Builders

Member since 26 Feb 2009

it all depends on architects spec.with building regs.once
you have this most builders could give you
a fixed price.

Answered 14th Mar 2011

clark&mccarthy building & carpentry ltd

Member since 3 Apr 2011

Hi your right, it does variy, depending on alot of factors, ie to what finsh, point of finish, access for water etc.

Prices variy from around £6000 upwards, depending on building control spec and calcs??

Answered 14th Mar 2011

JS Loft Conversions

Member since 12 Mar 2011

I think you will be closer to £9,000 for labor and materials. look out for deals on things like insulation. Right now B&Q and wickes are doing offers like buy one get 3 free.
Best Wishes From Trade Man's World

Answered 28th Mar 2011

Trade Man's World

Member since 12 Jul 2008

hi, the average cost for this project would be aprox £1200 per square meter of area then your required fittings would be added as extra to the schedule of build.

regards les davenport

Answered 14th Mar 2011

les davenport building contractors

Member since 18 Feb 2011

to be build on top of exsisting extension is normally straight forward ya ground floor extension will cost alot more just to get out of ground normaiily 15k with fittings

Answered 1st Apr 2011


Member since 31 Oct 2008

hi providing the exsisting footings are adequite enough for double story which you may need to do a test dig.All depends on what the arcitect specifies but i would base the new extention on 750/800 a square metrealso depends on finsh ans access.

Answered 25th Mar 2011


Member since 5 Nov 2010

I noticed you have planning permission etc, so take it you have approval to build on top of existing.
I would base the price on 1k per square metre, about £8k plus vat.
Any interior fittings may add to this.

Answered 15th Mar 2011


Member since 29 Oct 2008

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