Outhouse re-roof, advice please

[diy_fun_uk]

I need to arrange the re-roofing of an outhouse. It's approx. 10' x 8'. It's at the rear of a garden and only used for general storage. I don't therefore need a tier 1 job in terms of products used, however neither do I want the cheapest. A middle ground is what I'm aiming for. The existing joists will remain, existing ply and combo of felt and rubber coverings will go.

Couple of questions.

1. I intend to seek quotes for an osb/ply and felt re-roof. Given the requirement, does this approach seem sensible to you? Would stipulate felt like this, hopefully better than the cheapest:

Roof Pro Green Premium Shed Felt 10 x 1m | Roofing Felt | Screwfix.com

2. My intention is to stipulate 11mm OSB 3 board. Is OSB the logical choice for this application and is 11mm sufficient or should I go for 18mm? Or would you suggest ply?

Cheers.

 

[Alastairreid]

Osb3 18mm and I would use epdm.

 

[diy_fun_uk]

Osb3 18mm and I would use epdm.

Yeah I kind of thought after posting 18mm makes sense. I've been reading a few articles re good quality felt vs epdm. I'll weigh up with cost as one of the factors. It's a BTL property so whilst I need the work to be of decent enough quality, I won't necessarily spend as much as I would on my own outhouse, if indeed I had one!