stuff to stop condensation forming inside? Is there some shaped insulation foam I can buy or is there some other method to prevent thermal bridging

>>2607380 (OP)

do you want to insulate it or just stop condensation?



to stop condensation you buy the sheets with felt lining or apply a sticky felt.

the felt soaks up the moisture and releases it slowly stopping drips.

Wouldn't the felt end up growing mold?

>>2607380 (OP)

Provide some context. Is it just sitting over a chicken coop and collects condensation in the morning, or is it on the side of a house/shed and cooling the interior draws condensation?

It's a shed roof. I bought the place last year and initially it had styrofoam sheets as insulation. Only problem was that rats were nesting up there so I tore it all down last autumn. During the winter condensation was bad and there were drips all over the place.

Like the felt idea posted above I'm thinking of taping a few layers of foam underlay to keep the damp air from condensing on the cold roof

>>2607380 (OP)

put it over top of insulation and sheathing, like you would shingles

the increased surface area the felt provides will evaporate off the condensation faster than it forms and there won't be as much of it to begin with since they'd provide a slight insulation layer.

honestly never heard of anyone lining these with felt but it sounds like it should work.

I doubt it will actually work out that way. Cotton felt is extremely hydrophilic and it's a right pain to dry it out. It's what makes wet socks the worst. You would need wool or synthetic felt for this to work, because cotton in a moist dipping environment will never dry out.

>>2607380 (OP)

Why not just hang a sheet of plastic or tarp under the roof, like a tent? Keep it from touching the metal directly, to avoid the condensation forming on the plastic too.

Spray foam insulation.

here this is available from every corrugated sheet manufacturer for a small fee. 



i don't think its cotton its probably mostly recycled shredded clothing like painter fleece

>>2607380 (OP)

slant it so it drains in to a gutter

>>2607380 (OP)

That spray rubber shit. Flexseal

Or double it up using corrugated fiberglass with an air gap of 1/2"

if there's condensation on the underside then that means your shed is damp. either address the source of the moisture and run a heater to dry it out, or ensure that the roof is slanted and header is fully wrapped so that moisture drains to the outside and not into the structure 



read up on the importance of air circulation in rooflines if you do want to insulate it. you don't want to end up with moisture trapped between the insulation and the steel.
