How to damp proof and ventilate flat cold roof?
Posted: 14 Mar 2019, 13:37
Hi,
Sorry if this is the wrong place to be posting questions. I was hoping someone could help me with my workshop build plans.
My plan is to make a flat roof shed which will be insulated throughout with some form of mineral wool/ Rockwool. The reason for this is that sound is a big concern where I'm based.
I'm then going to have a vapour barrier on the inside of the studs followed by either plywood or OSB. The outside is going to go studs, OSB, breather membrane, 25mm batten and finally feather edge cladding.
As I'm going to be using mineral wool insulation I've opted to go for a cold roof as opposed to a warm one. From what I could tell a warm roof will only work with rigid insulation.
My question is about the best way to ventilate and damp proof the roof? I've done a bunch of research and understand that I need to leave at least a 50mm gap above the insulation to allow for ventilation. But where should I put my breathable membrane?
From what I can tell if I follow the examples (https://www.rubber4roofs.co.uk/epdm-col ... oof-design) I would have no protection from moisture if something is able to get through my roof (OSB and felt)?
I've read through MikeG's guides and know what I'd do if I had an apex roof, but the fact that I'm going with a flat roof design is confusing things.
I hope that makes sense, thanks for the help!
Sorry if this is the wrong place to be posting questions. I was hoping someone could help me with my workshop build plans.
My plan is to make a flat roof shed which will be insulated throughout with some form of mineral wool/ Rockwool. The reason for this is that sound is a big concern where I'm based.
I'm then going to have a vapour barrier on the inside of the studs followed by either plywood or OSB. The outside is going to go studs, OSB, breather membrane, 25mm batten and finally feather edge cladding.
As I'm going to be using mineral wool insulation I've opted to go for a cold roof as opposed to a warm one. From what I could tell a warm roof will only work with rigid insulation.
My question is about the best way to ventilate and damp proof the roof? I've done a bunch of research and understand that I need to leave at least a 50mm gap above the insulation to allow for ventilation. But where should I put my breathable membrane?
From what I can tell if I follow the examples (https://www.rubber4roofs.co.uk/epdm-col ... oof-design) I would have no protection from moisture if something is able to get through my roof (OSB and felt)?
I've read through MikeG's guides and know what I'd do if I had an apex roof, but the fact that I'm going with a flat roof design is confusing things.
I hope that makes sense, thanks for the help!