Building an extension timeline
Read through our extension checklist to keep on track and make sure nothing's forgotten!
Works will vary depending on the type of extension you're having done, but a timeline will give you a better understanding of what's involved.
From laying down the foundations to finishing the plastering, here's a general works plan for a standard single-storey extension:
This refers to everything before the point of finished plastered walls.
- Builders will arrive on site.
- Preparation begins for the groundwork and foundations.
- Superstructure starts, which includes building up a (DPC).
- Drains are installed.
- Lintels are fixed in place.
- A concrete floor and insulation is put in place.
- The building of external walls begins, which includes block work or brickwork
- Cavity wall insulation will be fitted.
- Wall tiles are then used to fix the new walls to those in the existing house.
Week 6 - 7
- Internal walls are built at this stage.
- Followed by the roof structure and roof covering.
- A carpenter will build the roof structure.
- Roofing membrane will then be laid over the rafters before roof battens are fitted in place.
- Windows and doors will now be installed.
- First fix carpentry, plumbing and electrics begin.
- The extension should be watertight by now and the three trades work closely together at this stage to ensure each knows what the other is doing.
- Stud work might begin now.
- Break through from the existing house and steels are put in place.
- This can be a very messy time, so if you're living at the property or just don't want your things to get covered in dust, it's a good idea to seal everything off as much as possible.
- Plastering, followed by a period of about a week for drying out.
This refers to everything that comes after plastering has finished.
- Second fix electrics meaning sockets will be made live, switches put into place and lights will be fitted.
- Second fix plumbing where taps are installed and connections completed.
- Flooring will be fitted and kitchen units installed, if applicable.
- Snagging, which means any leaks, problems with electrics and anything that's not quite right should be reported to the builders as soon as possible after finishing.