Breathable or non-breathable membrane?

[GARYF123]

Hi,
My pitched roof is going to need a refurbishment soon and am wondering what is the best membrane to replace the old underfelt with, breathable or non-breathable. It is a tiled roof.

Many thanks in advance,

Gary.

 

[freddiemercurystwin]

You can never have enough ventilation in a roof so breathable everytime. Even if you have existing vents at the eaves.

 

[garyo]

I'm about to put breathable on a rear extension. First time I've used it - can't believe how thin it is, but it seems to be very very resistant to tearing.

The reason I thought I'd add to the thread (it's not a hijack really!) is:

a) the instructions recommend using double sided tape to join all laps - Do roofers actually tend do this? I don't see why this would be any different a situation to mineral felt? I'm trying to get it up in drizzle so don't fancy my chances of the tape working well.

b) Where my new extension fly-in forms a valley with the existing roof I'm a valley is formed. I could line the valley in breathable or mineral (I have rolls of both) - which of the two is seen as the most hard wearing option in what could be a high-traffic area?

Cheers

Gary

 

[SurreyRoofingEstimator]

The only reason to tape the joints is to create a sealed roof, no reason to do this in your case

 

[noseall]

Tape may also help stop bits flapping about particularly on larger batten spacings.

We don't bother though.