Range from the cheapest single storey extension £51,320 (JPL Building and Landscaping based in IG9) to the dearest single storey extension £55,000 (Nouvell Decor based in IG9).
Comparing extension builders estimates for fitting a downstairs toilet gives you an idea of who will be better value but the best way to compare costs is to get actual quotes.
What to do - Get rates and quotes to build a single storey extension in IG10 by posting a job with HaMuch and we will send it to extension builders in IG10.

"Single storey extension"
EPPING FOREST