If the foundation needs underpinning then this can add £000's to the cost.
Or even make it not viable (shifting clay or a raft required?)

If access is limited or there are other specific site conditions which mean
the builder is going to spend an extra week there, then this too will bump
up the price.

A pitched roof can be 33% more than a flat one.

So your £15,000 estimate quickly turns into a £30,000 quote. Or it puts you
off doing it, when in fact you could get it done for £10,000

You really need a local builder to look at it and give an estimate based on
his past experience.

You won't get an accurate/meaningful estimate here I'm afraid

dg

"SuzySue" wrote in message
om...
I was thinking of maybe having a bedroom extension built.

It would be on the 1st floor and on top of an already existing flat
roof kitchen extension. I don't know if the foundations of the
kitchen extension were designed to hold the weight of an additional
floor as it was already built.

The extension would be approximately 7ft x 7ft built of blocks and
pebble dashed. The wall of the house which would have to be knocked
out to extend outwards would be (I assume) a load bearing wall as it
is an external wall).

Was just wondering if anyone would know roughly what it might cost to
build such a bedroom extension. Just a vague idea...