Wrong felt

[joinerjoe]

I recently purchased a roll of roof pro torch-on roofing felt underlay from Screwfix by mistake, I meant to buy roof pro torch-on roofing felt cap sheet, both the same price £66.99, just clicked on the wrong item. Anyway, I only realised the mistake after I came to installi and had cut the first piece and stripped the shed roof, so no going back at that stage.
My question, given that it's already on, does anyone know how long it will last, t seems like good quality.
I didn't use a torch-on it just fitted as normal felt.

 

[Deluks]

Presumably the cap sheet has the stone chips in it.
This protects the felt, to some degree from damage, so without it, your felt may degrade prematurely.
If you want it to last, put a second layer on.
These products are designed to work together, just fixing a single layer down could result in ripping and splitting.
How did you fix it?

 

[datarebal]

Underlay is usually half the thickness of cap sheet .

 

[joinerjoe]

Thanks for your reply. I installed the felt in the usual way clout nails and adhesive on the joints

 

[datarebal]

Torch on ?