A flat roof extension is a great way to add extra space to your home without splashing out on the costs of a pitched roof extension. Often exempt from planning permission rules, you can build a flat roof extension up to 3 metres in height as long as it's not visible from a road. But how much do they cost in B20?

A flat roof extension ranges from the cheapest of £21,528 (D&J Advanced Builders based in B44) to the dearest of £22,800 (Sperin Interiors based in B66), but these are just estimates. While they give you an idea of who will be better value, the best way to compare costs is to get real quotes. 

Find out how much your flat roof extension will cost in B20 by posting a job with HaMuch. We'll send it to extension builders in B20.