How much contingency buildin work

[nachosTrafficante]

Been quoted £60k for running’s small kitchen into kitchen diner with utility by building extension, new megaflop, moving stairs, insulation loft a demolition of outbuildings.

That’s just building.

House bought for 485, ceiling price for house probably 560k

I'd probably want another 15k in the kitty. There might be unforeseen problems but you might change your mind about things mid-way through or the estimate can be a bit inaccurate if the builder forgot about a thing or two.