Range from the cheapest single storey extension £47,000 (A S G Developments - Herts LTD based in AL10) to the dearest single storey extension £54,360 (NJG BUILDING SOLUTIONS LTD based in AL7).
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 AL9 by posting a job with HaMuch and we will send it to extension builders in AL9.

"Single storey extension"
WELWYN
| Location in UK | Hourly Rate | Daily Rate |
|---|---|---|
| Single Storey Extension near Hatfield | £54 | £241 |
| Single Storey Extension near Potters Bar | £38 | £240 |
| Single Storey Extension near Welwyn Garden City | £36 | £229 |
| Single Storey Extension near St Albans | £52 | £242 |
| Single Storey Extension near Cheshunt | £41 | £244 |
| Single Storey Extension near Hertford | £39 | £247 |
| Single Storey Extension near High Barnet | £37 | £236 |
| Single Storey Extension near Borehamwood | £37 | £238 |
| Single Storey Extension near Harpenden | £69 | £256 |
| Single Storey Extension near Hoddesdon | £40 | £252 |