How Long Does a Loft Conversion Take?

Before anyone arrives

Measured survey and drawings usually take two to three weeks. Structural calculations run alongside or just after. If the scheme is permitted development you can start once building control is notified. If it needs planning permission, add the statutory determination period and allow for validation delays at the start.

Party wall notices, where the work affects a shared wall, carry their own statutory notice periods. Serving them early costs nothing and serving them late stops the job.

On site, by conversion type

Timings assume a standard house, reasonable access and no surprises in the roof.

Rooflight conversion, no dormer: roughly 4 weeks · Rear dormer with one bedroom and en suite: 5 to 6 weeks · Hip to gable with rear dormer: 6 to 8 weeks · L shaped dormer, two rooms plus bathroom: 8 to 10 weeks · Mansard or roof raise: 10 weeks and upwards

The noisy and the disruptive weeks

Weeks one and two carry the noise: opening up, cutting timber, dropping steels into place. If anyone works from home, this is the fortnight to be elsewhere on the loudest days, and a good contractor will tell you which those are.

The genuinely intrusive moment is forming the stairwell, when a ceiling comes down in the house below. After that the work moves upstairs and the house returns to something like normal.

What pushes programmes out

Delays are rarely mysterious. They cluster in the same few places every time.

Structural surprises once the roof is open, such as undersized or damaged timbers · Late decisions on staircase position, sanitaryware or window sizes · Long lead times on made to measure staircases and glazing · Building control inspection scheduling at key hold points · Weather during the days the roof is open, which good sequencing minimises

Keeping it on time

Make the decisions that have lead times first, then keep a weekly written update rather than a daily conversation on site. A programme with named stages and expected dates is easy to check against reality, and it makes slippage visible while it can still be recovered.

Frequently asked questions

Can I live in the house during a loft conversion?

Almost always yes. Access is external through the scaffold and the roof for most of the build, with one significant intrusion when the stairwell is formed.

How long is the roof open to the weather?

Usually a matter of days, and the opening is temporarily covered outside working hours. Sequencing aims to get the dormer carcass weathertight as fast as possible.

Do I need to move out for the staircase?

No, but expect one dusty, noisy day in the middle of the house, with the landing sheeted and the room below out of use.

How far ahead should I book?

Allow six to twelve weeks of design, calculation and consent work before the first day on site, longer if a planning application is required.