Breathable membrane problem

[Ronob]

just been up in the loft, house is a 1920’s semi, and noticed that the existing membrane between the tiles and roof joist (rafters) is worn and torn in several places, some quite badly.

Is there anything I can do besides have the tiles off the roof and relay the whole roof? - I don’t have a big budget for that!

 

[noseall]

Is the roof leaking? What sort of tiles do you have on the roof?

 

[Notch7]

Is it torn underfelt rather than breather membrane?

 

[Ronob]

Roof shows no sign of leaking, come to think of it, not sure if it’s membrane or felt, it’s old and where it’s torn it has the appearance of a black paper, maybe a pitch paper?? With the possibility of some kind of woven thin thread - couldn’t be certain of that (I need to put a light up there!).

As for the type of title, I really don’t know, they are flat with a slight rough texture to then as if coated in sand. They are not the wavy sort - that’s the best I can do

 

[Ronob]

Just looked at a builders merchant website and the tiles look more closely like the Redland plain concrete tile.

 

[wwwebber]

My house has no membrane whatsover and has no leaks. I have no plans to put a membrane in either. If you have no leaks then a torn membrane is not an issue.

 

[datarebal]

As above but add the felt isnt there to keep the rain out.

Sounds like sisalkraft underlay. probably concrete plain tile

 

[^woody^]

My house has no membrane whatsover and has no leaks. I have no plans to put a membrane in either. If you have no leaks then a torn membrane is not an issue.

What tiles are covering it? That makes the difference.

 

[^woody^]

As above but add the felt isnt there to keep the rain out.

That's odd. Why is it designed to waterproof - waterproof material laid in a way to be waterproof?

 

[datarebal]

name a waterproof underlay, where it states waterproof on the wrapper...

 

[Ronob]

name a waterproof underlay, where it states waterproof on the wrapper...

Yeah, I went to a builders merchants today and asked about underlay, they also asked if I had a leak because, they said, underlay isn’t for waterproofing, it is basically draft-proofing! And condensation reducing.

Anyway, he had the suggestion that I buy a large sheet of polystyrene and cut it to size (width between rafters) and shove that in, which will add insulation - any thoughts on that?

 

[Mw Roofline]

I think that redland spirtech is fully waterproof but about £200 a flippin roll.

 

[datarebal]

I think that redland spirtech is fully waterproof but about £200 a flippin roll.

for how long?

 

[Notch7]

Since a roof has loads of tile battens nailed through the membrane wouldnt it be pretty difficult to achieve water tightness -although I appreciate the rafters are the high pojnt since the membrane must sag a little between rafters.

 

[datarebal]

oh really... 10 mm drape , some of the best known names can drip if exposed to any amount of rain