How-to · 4 min read
How long does a house extension take?
The build itself is only part of the timeline. Design and approvals come first, and getting those right is what keeps the build fast and calm. Here is a realistic breakdown for a typical extension in our area.
| Stage | Typical duration |
|---|---|
| Design and drawings | 2 to 4 weeks |
| Planning or permitted development approval | 4 to 8 weeks |
| Building control and structural design | Runs alongside the above |
| Single storey rear extension build | 10 to 16 weeks |
| Double storey or larger build | 16 to 24 weeks |
Why design and build is faster
When one team designs and builds, the drawings are buildable from day one, materials are ordered early, and there is no gap where a separately drawn scheme has to be re-priced and re-planned by a contractor. That alone often saves weeks.
What can add time
- A full planning application rather than permitted development.
- Party wall agreements with neighbours (start these early).
- Tricky groundworks, trees or drains discovered on site.
- Long lead times on special items like bespoke glazing.
We give you a clear programme with your fixed quotation, so you know the milestones before we start.
Frequently asked questions
How long does a single storey extension take to build?+
Usually around 10 to 16 weeks on site once design and approvals are complete, depending on size, glazing and finish.
Can I speed it up?+
The biggest time saving is starting design and approvals early and choosing permitted development where possible. A fast-track programme with extra resource can compress the build too.
Do I need to move out?+
Usually not for a single storey extension, though the kitchen may be out of action for a period if it is a kitchen extension.