[bigbavarian]

Hello everyone,




Im bulding a shed and am thinking about a metal roof instead of shingles. I have been watching a few videos on them and they all seem to have the 1x4s down underneath although they are typically going over old shingles. I have a brand new roof and was wondering if I can put down some membrane first and then put the panels directly down without the 1x4s.

Thanks


Stephen

 

[Windows on Wash]

The purlins are for leveling or air flow. Neither seem to be applicable on a shed.

I would just put some underlayment (i.e. slip layer) and put the metal direct over the shingles.

 

[u2slow]

If the shed is enclosed enough to create a temperature differential with outside, you'll get condensation. OSB(?) won't like that moisture. Definitely use an underlay. My shop is built to local codes with 1/2" ply sheathing, #30 felt, and galvalume metal panels.

Strapping instead of sheathing will breathe better for a 'cold' shed. Its working fine for one of my enclosed sheds, and my open woodshed.

 

[Windows on Wash]

"Brand new roof" sounds like shingle or plywood. Neither of which are vapor open.

If by "Brand new roof" he means structure, then yes, they will need some vapor control and or ability to dry.

 

[bigbavarian]

Sounds like I should have been a little more specific. I am literally in the processing of building this shed. The roof currently has 3/4 in (23/32) OSB sheets on it and nothing else at this time. I was going to put shingles but at the last minute I saw a picture with the metal panels and it looks nice. So I was looking around more and although all the videos I saw have people placing the 1x4s down, they are all over old shingles. I don't have anything there now so I was wondering if I can just put something down like tar paper or a membrane and then put the metal right on top of the membrane. This is a typical shed in upstate NY. Not heated. I can put the 1x4s down but I would rather save the time if I don't need to.

 

[roofermann]

Windows has given you the correct answer.