Building cost per square metre for extensions

[Rossmoyne]

Can it really be that, in the present economic climate, with people competing for business, building costs are quoted arbitrarily at �1,000 per square metre by architects and assorted web sites, no matter what is being built or where? Are there not some British or Polish builders in the West Country who might say this need not always be the case? The reason for this question is parental concern for daughter and family, who have planning permission for an uncontentious, and what they thought a reasonable, extension to a very small house, only to find that the area multiplied by this �1,000 figure is beyond their current means. Would be grateful for any views, thoughts or recent experience on this subject.

[buildersmate]

This is precisely the problem with this sort of very rough estimator. It doesn't apply in London or in rural Scotland, or to bungalows, nor three storey buildings on steep slopes, or to small extensions.
Fact: there is no such thing as an 'average' house.
Kitchen extensions: a significant element of the cost is the new kitchen, but you can spent �1500 or �15k on these. How does that work against �1k sqm? - it doesn't.
The way to get the best price is through competition - three builders all keen for the work - that assures you are getting a reasonable price.
If you want to understand whether what you are thinking is vaguely within budget, ask a builder around - not for a quote, but a rough appraisal of what it might cost. Won't take long and gives you enough to go on.

[Rossmoyne]

Many thanks, buildersmate, that's a refreshing dose of common sense and a great practical help. Will forward it to daughter. Thanks also for speedy reply.

[The Builder]

I couldn't agree more with what BM has said. In common with many small builders, I always calculate from first principles - ie I use a spreadsheet to list all trades and all materials connected with each trade. I never fail to get a figure that I'm happy with, and is quotable. Larger builders can't be bothered to be honest, so they use arbitrary sq. metre costs. The cost difference can be quite staggering :o)

[Rossmoyne]

Thank you, "The Builder", very clear and useful, much appreciated. Have forwarded it to my family, who are a little more cheerful than they were this morning!