Roof beams slighty damp, normal in old house with no felt under tiles?

[Jblakes]

Evening all,

Basically as the title says, we have a big roof space with part of it having just tiles, no felt underneath, the house has had an extension so the newer bit has felt.

The wood that holds the tiles on the section with no felt are slighty damp, is this normal?

There is good airflow around the roof, but looks like somebody has concreted the gaps between alot of the tiles.

Anybody any ideas, the other side of the roof (newer side) looks fine and I can't see any that would indicate a leak.

Regards James

 

[Culturealgap]

The moisture is the result of condensation.
In the mid 80s, I bought a cottage in co Wicklow in Eire, which had a bedroom in the upper floor. Almost an attic but plenty of headroom originally used as a bedroom.
The under sides of the slates were plastered with a lime plaster to absorb the damp.
Oddly enough, felt can cause the battens to rot by retaining the condensation.

 

[Jblakes]

Is it standard practice to plaster up onto the slates? And does it work? Seems like a good idea. I was gonna shove wood fibre boards between the rafters on the side with no felt

 

[Jblakes]

Hi all,

I've been reading up on it and it's called touching. Has anybody done this, not had it already installed?

My concern is that if I do this I will block the air flow into the loft. Can this cause an issue or will the lime plaster absorb the moisture and move it out the loft?

Regards James

 

[stuart45]

Condensation in roof spaces wasn't as much of a problem when torching was done. It became one when they started getting insulated. Before insulation was used ice dams and icicles hanging down from the eaves was more common.

 

[eezageeza]

Hi all,

I've been reading up on it and it's called touching. Has anybody done this, not had it already installed?

My concern is that if I do this I will block the air flow into the loft. Can this cause an issue or will the lime plaster absorb the moisture and move it out the loft?

Regards James

The old part of our house has tiles torched onto the battens. In our case the nibs of each tile are set into a seam of what I think is lime mortar along the top edge of the battens. There's still plenty of air flow between all the other tile edges (I guess the tiles are hand made, and not entirely flat!) and there's no damp up there at all.

 

[eezageeza]

I just googled roof tile torching, and can see from photos on there that the torching on our roof is rather less comprehensive than most! A lot of tiles/slates look to have been torched along all edges, making a pretty comprehensive seal, so those roofs would be much less well ventilated than ours. In that case you'd need to consider how much air is getting in under the eaves - in our case, that would still be plenty I guess, but every roof is different!