Single Storey Extension Cost

6 Sep 2017
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United Kingdom
I live in the Peterborough area and am considering a very basic approx. 6m x 3m single storey 'lean-to style' side extension to my detached house.

The budget is VERY tight, so am looking for just the shell really and I'd look to do all internal work including the windows and doors myself/with help from friends who are electricians/plumbers etc. So foundations, 3x walls and a lean-to tiled roof is needed. The external house walls are cavity breeze block with render over. The house is on a corner plot, so there is plenty of room for a side extension, without it being anywhere near the boundary.

Can anyone advise what sort of cost I'd be looking at? I happy to do any labouring required to make the job cheaper (i.e clearing the site back to earth etc...)

I understand it's not just as simple as giving a price, but I am just looking for a rough guide to see if it's anywhere at all near my budget as I'd hate to pay for plans to get drawn up in order for builders to quote, only to find out that the build cost is way above what I can afford.

Also, just to complicate matters, there is a foul water inspection chamber within the area that the extension would go. This is owned by the water company and serves my house along with two neighbouring properties, so would need moving - does anyone have any idea how much this would likely cost, or would there be any cheaper alternatives to moving it? (the water company state they will not permit an inspection hatch within a building)

Many thanks
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If it's rendered block you may as well do it all yourself and have a Pro render it. It should be quite easy for you to cost the materials.

A mate of mine is having something similar built (but with brick outside). And it's costing him £1060 per sq/mtr all in so yours would be around £19,000 if you didn't lift a finger to help.

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