My parents are having a complete roof renewal and the builders have taken off the tiles and also the wood slats underneath, replacing this wood with an waterproof membrane. Mid-job, last weekend, the membrane tore in the wind and let water in and my folks (elderly but reasonably switched on) are getting quite worried about why the wood couldn’t have just stayed there.
I’m a competent DIYer but don’t know enough about this to set their minds at rest. Could someone explain this sort of membrane to me (is it standard practice, what should they look out for?) and is it any good.

Many thanks

The wooden battens are what ultimately secure the waterproof fabric. It would only be secured loosely with a staple gun until the battens are fitted. If there is a rip then that section needs to be locally replaced

Theyd obviously put the membrane back but not the battens hoping that the membrane would keep the roof weatherproof briefly.

Old roofs wouldnt have had a membrane or felt underneath the battens so they are adding weather protection. Then the battens go back on and the tiles hang off the battens again.

Thanks for the replies but I need to make myself clearer. The wood they removed wasn’t the thin strip batons that you normally see holding the membrane on but a complete wooden covering of the whole roof underneath the tiles.
This probably won’t come up to the top of the list again so thanks again and I’ll research a bit more to stop the old codgers fretting.

having an extension done at the moment .

to link noew roof to the old they had to take the old wood and felt away and replaced with the membrane , then add batons and finally the tiles .

the membrane is like gore tex , waterproof on one side and let the air out from the inside .

Is the roof a shallow pitch, what type of tile, were the no laths on the roof at all, was there any existing felt? Can you run through a quick make up of the original roof??

Cheers Chris, thought it must be something like that but convincing the wrinklies that a modern solution is better than solid wood is sometimes difficult!!

Facts: The thin lats that covered the roof are how they used to do it before felt was used. Modern practice is to remove thin lats (after removal of tiles and tile lats and then re cover roof in a breathable waterproof membrane to vent the roof space but also to keep water out. Once the tile lats are put on and the roof is retiled eveything is ok. It sounds like the membrane has been damaged before the tiles are put back. It needs repairing/replacing before re tiling.

Facts as much as you like, if as it sounds the roof was once covered in a sheet material, it was for a reason?

Was it sarking boards or close boarding? On some houses with plain tiles what I would refer to as feather edge was sometimes used to form the edge to hang the tile on. More commonly batten was/is used. If it was this then I would suggest there would be no problem with the latter technique. If it was sarking board, namely flat boarding across the rafters then it may have either been in place for structural reasons, or to fix slates in if this was the original roofing material.

^^^ and there you have my gist!!^^^

Sarking boards +1

As long as it’s not in Scotland it will be fine. (I think it’s still a requirement in Scotland for sarking boards as well as a roofing membrane)

Whatever the reason for the boarding being there originally it is quite likely to have gone rotten (probable lack of breathing) and is why the roof is now reqiring to be be replaced with the current’ system.
Just make sure the torn section is replaced and it will all be good.

We did an extension a couple of years ago and had to board the roof with 18mm osb because it was supposedly self supporting as the gable was glass and there were no joists.

Roof constructed as a diaphragm due to the gable offering no lateral restrant. I’ve done 2 in my time…. one was a SIPS solution the other an OTT engineer.

Often have 12 mm ply due attic trusses etc. As above, the ply provides lateral restraint.

STW comes good, many thanks for all your advice, sarking boards seem to be the correct description of what they are. Thing is they weren’t in any way rotten just the tiles had become brittle.
Now I just have to see if they were meant to be there for lateral support.

Cheers.