Roof tiling

me4many

Ensure that the crafts persons fitting the roofing membrane over the rafters - that the membrane is well sagged between the rafters.

The membrane should not be pulled Taut.

In many roofs the membrane is pulled taut, and therefore up tight against the underside of the battens, which is incorrect.

me4money

Unfortunately many of the incompetent morans fitting roofing membranes on top of the rafters never heard of this either.

When I’m looking after the construction, I ensure that the persons laying the membrane that it is fitted well sagged, between the rafters.

All materials on building sites must be fitted in accordance with the manufactures instructions. Many workers on building sites never read these instructions.

Slating and Tiling instructions state that the roofing membrane must be fitted well sagged between the rafters

The purpose of the roofing membrane is to prevent any ingress of rainwater blown in between the tiles or slates during very strong winds, from getting in to the attic area.

The membrane is sagged to form troughs between the rafters, to enable any of this rainwater to flow down in to the gutters.

If it is not well sagged, then the membrane will be up tight against the lower surface of the battens which will prevent the rainwater from escaping from the membrane.

Rainwater may build up and soak in to the battens and may cause Wet Rot.

if there is cracked or damaged slates or tiles allowing ingress of rainwater it could cause excessive damage.

If spray foam is sprayed under the membrane, it will expand and will push up the sagging in the membrane, up against the roofing batters.

It’s hard to believe your comment.

If you read what I wrote, then you should understand that the sagging in the membrane is to allow ingress of rainwater to flow down the trough in the membrane and under the battens.

Do you have any idea of how much space the rainwater needs to flow under the battens without coming in contact with the battens.

Why do people here - offer no advice when requested - And instead try to find anything whatever to criticise in any advice given.

Note: I did not ask for any advice whatsoever.

Thanks Lumen.

That photo shows how it should be done.

Unfortunately most people fitting the membrane pull it tight and do not allow any gap under the battens, which is not in accordance with the manufactures instructions.