What is torching?

Tŷ-Mawr ‌‌ posted this on 6 Apr 2016

What is torching?

In the days before roofing felt, torching or lime mortar was used on the underside of tiles or slates to keep them in place and to prevent strong winds from getting under the tiles and lifting them. The torching on clay tile roofs contributed to securing them in the days before nibs were added to hold them on the wooden battens.

Torching is still used today in heritage properties, as an alternative to a modern breathable membrane.

If there is a situation where the original roof covering is not going to be removed and there is no roofing felt then torching is a good idea prior to installing insulation such as sheep’s wool between rafters.

We would recommend using fat lime fine hemp plaster for torching.

If the customer specifies sand lime we do do a torching mix which is a well fibred fat lime sand plaster, but we would encourage people to use the fine hemp plaster first and foremost as it is packed full of fibre, it sticks well to slate, tile and stone and is lightweight.

Categories: FAQs