Keep the weather out

Whenever the building is open to the weather for more than a few days, and particularly on a re-roof, a loft conversion or a fire or water damage repair where what is underneath is finished or occupied. A week of rain into an open roof costs more in damage and delay than the cover does, which is why insurers and main contractors ask for one.

A temporary roof on a typical domestic re-roof is normally a day on top of the scaffold erect. Larger spans and commercial buildings take longer because the beams are craned or assembled in sections. We build the time into the programme so the roofers are not standing about waiting for it.

Yes. A sheeted temporary roof catches wind in a way an open scaffold does not, so beam selection, tie positions and the supporting scaffold all come from a design rather than a rule of thumb. The design is issued with the handover paperwork.

It is designed for wind loading, tied into the structure and inspected after any severe weather, which is a legal requirement as well as good practice. In an exceptional storm we may recommend relaxing or removing sheeting temporarily, and where the forecast is bad we would rather come out and check it than hope.

Yes. A temporary roof over one section, a bay or a rear extension is common where the rest of the building is watertight. It is designed the same way, just over a shorter span, and it usually works out considerably cheaper than covering the whole roof.

That is the point of it. With the sheeting up and access lifts built in underneath, a re-roof or a structural repair carries on in weather that would otherwise stop it, and daylight through the sheeting is better than most people expect. Task lighting can be run off the scaffold if the job needs it.