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How much would it cost to build a 3m x 9m single storey extension to a semi-detached house approximatley

the extension would be a small utility room, entrance lobby and extension to the existing kitchen. I would like an approx price for the structure/ roof and all new internal walls including any plastering works, electrical works and mechanical works.

Yrob_walker1984 16th Jan, 2012 Extensions
11 Answers u78

Anything from £1000-£1700 per m2.Depends on where you are and who quotes it.There are lots of factors that may change it anyway.This wouldnt allow for foundation variances.If you needed to excavate to a depth of say 2.2m or have piling,this would cost you more money.As for electrics etc,we would need to know roughly how much is needed as i have had clients ask for 20 downlights in one room lol.Only real way of getting a good estimate or an exact quote would be to get a few tradesmen to visit the job.

Roc builders 16th Jan, 2012

Going from various previous jobs, The average cost is about £1000 sqm. This is to a plastered finish with plumbing, electrics, windows, plastering etc etc This is dependant on what finish you have inside the property, whether it be kitchen, Bathroom etc. If its just a basic room with just painted walls and carpet it will be cheaper, but its a good average cost to go by before you get too involved with builders and planning office etc. Hope this helps.

Empire Renovation 16th Jan, 2012

I would think you are looking at around the £30000 mark, but obviously that would depend on what type of soil you have, existing footings and also if any trrees interfere with the footings. Hope this helps.

Solutions Carpentry & Building 16th Jan, 2012

Hi Rob,
I do not know where you live and area, the price could range from £800 to £1000 per metre square, so your extension should cost you £21600 or 27'000

kind Regards

Howard @ Ullyses

Ullyses limited 16th Jan, 2012

At current rates the cost of your extension would be about £25 to £30k

Prestbury Developments and Refurbishments Ltd 16th Jan, 2012

Difficult to price without seeing drawings & regs but a good guide would be between £1200-£1500 per m2 depending on spec.

m w building construction and property maintenance 16th Jan, 2012

depending on the material and the final quality of your fixtures and fittings i would say around £18,000- £24,000

banktop construction 16th Jan, 2012

if you allowed £27,000 then you would,nt be far off.


hi Rob
you wouldn't be far out with budgeting 20k-25k as a finished plastered shell with skirting and doors. ready to paint

jd kent 16th Jan, 2012

Around £25000

Spencer Construction 17th Jan, 2012

32k plus but this is a rough guesstimate ,important factors inc ground conditions,access to site,spec of elecs and mechanical ect ect

substructure 16th Jan, 2012
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