Shed felt - one or two layers?

[Gossamer]

Evening,
I need to re-felt my shed.
Is a good quality felt ok, or should I spend more time / money on a separate underlay and topsheet?
Cheers.

 

[Nige F]

Single layer good quality is fine - with cold lap cement under any laps

 

[Gary-greentree]

A good quality mineral felt wound do the job

 

[Bosswhite]

I would fix tile battening across the roof one length on each edge of shed and a couple of lengths in the middle to stop storm winds getting under the felt sheeting and ripping it off in bad weather