Roof repair - can I use torch-on felt nailed only, as underlay (instead of 1f)?

[DIYNotIan]

Hi

I've got a repair to do to my roof. The roof has sarking boards, with 1f felt on top, battens, then slates. I'm repairing a hole in the sarking and felt from where a flue was removed. The whole area to be repaired amounts to approx. 1.2m x 1m.

I was kindly given some felt to use for the repair. I was told it was 1f but I've collected it and it's actually torch on. In fact, I was given two different rolls. One is this stuff:

IKO Glass Torch On App Universal Underlay 16m - 61020216

IKO Glass Torch On App Universal Underlay is a great product, made of a glass fibre base and coated with APP modified bitumen. This product has a flame dispersible polyethylene on the bottom surface for application, whilst the top is finished with sand. When using underlay you heat the...

www.jtatkinson.co.uk

The other felt is thicker and I'm guessing is used for the top layer in a torch on system? Photo below of that one....

My question is whether either of these can be used instead of 1f for the repair? I'm only looking to nail it, as you would with 1f. Or do I need to make a trip to the BM and fork out for a roll of 1f?

Many thanks

 

[DIYNotIan]

Hi all

Hoping to do this repair at the weekend, so any thoughts as to whether I can use either of these torch on felts as a substitute for 1f (and use it in the same way as 1f - i.e. nail it only) would be a great help...

Ta

 

[datarebal]

No reason why not. The 1f is non breathable nor is the t o

 

[DIYNotIan]

Excellent, thanks for the response.

Which of the two would you use? The thinner underlay as per the link, or the one I took a photo of, which is much thicker and I presume a top felt?

 

[datarebal]

The underlay probably look neatest ...your choice really

 

[catlad]

The water won't care which you use.