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

[Oxbow16]

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:

 

https://www.jtatkinson.co.uk/iko-glass-torch-on-app-universal-underlay-16m-61020216

 

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

 

 

 

[Oxbow16]

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