TOPIC: Is A Metal Roof Right For My House
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I need to replace my roof and wanted to go with metal for a number of reasons. My house is a log cabin. There is no attic or “attic space”. Standing in the bedroom upstairs and looking up, working from the inside to the exterior, I have logs that act as roof trusses. On top of those there are 2X6s running perpendicular across the logs and then covered with ice and water shield. Then there is 3” rigid foam insulation then on top of the insualtion then there is 1/2” OSB sheathing and finally felt paper and the shingles. My concern is when warm from inside meets cold air outside it will cause condensation and rot out the wood as there is no way for condensation to escape. My thinking is to install felt paper on top of the shingles then add sleepers ( 2X4s running from the exterior bearing walls up to the ridge) 18” OC. And securing the metal panels to the sleepers. Also adding vented soffit and a ridge vent. Any input would be greatly appreciated! Thank you.
If your current system is working, I do not think that adding metal on top will change it. However, that said, I appreciate your thoughts. Metal panels could not be installed over your vertically oriented sleepers. You'd need to put cross battens or solid decking on top of the sleepers an then attach the roofing to that.
Thank you for you input. However, I’m not convinced the current system is working as the cabin has never been a permanent year round residence. In that I mean there hasn’t been sufficient evidence that condensation will or will not be a problem since the heat had only been used a couple times a year.
Why would I have to install cross battens as apposed to vertical? I’m not doubting you, I’m just trying to fully understand so I can make the best decision! Thank you.
Sorry ... I was unaware that this was the first the cabin has been heated. That does add a new dynamic and you're right to be working through this. Vertically oriented metal roofing panels, by design, must be installed over either solid decking or horizontal strapping spaced per manufacturer specifications. They cannot be installed direct over vertical strapping as the panels will sag between the straps and also not be walkable.
Ok, that does make sense. I was hoping with the panels be 3’ wide I’d be ok with 18” OC sleepers. Do you think I could use 3/4 furring strips instead of 2X4s for the vertical sleepers and the cross battens? It’ll save on cost and I’d still have the air gap for ventilation.
Yes, you should be fine using the smaller boards ... not unusual at all.
Great, thank you! Any thoughts/ideas about the possible condensation issue? Obviously, moisture can be detrimental to a log home.
Between the insulation, the decking, the airspace, and the ventilation, I feel like you are protected against warm moist air from inside the home reaching a cold surface and condensing.
We applied a metal roof on an area of our cabin that had to be rebuilt the only problem is they did not apply anything under the metal roof leaving it exposed and now we have so much condensation The other half of the cabin the metal roof was applied over the existing shingles. Do we need to remove the metal roof on the rebuild and apply plywood with if so what else needs to go on the plywood to help
If you do not have any plans to modify the interior, you will need to remove the roof and install solid decking as well as some sort of vapor barrier.
thought so thank you now I just need to convince him
suggestions on vapor barrier?
The solid decking in conjunction with a proper underlayment will suffice.
On the interior side of things, that is a different set of questions.
Please tell us what to do we do, we heat it with a propane fireplace- when there we have it at 70 when not there we have it at 50. We do not want to have things get ruined so please let us know what to do with the interior side of the roof too. We will no doubt wait till spring to remove the panels and apply the barrier and plywood and not go up during the winter
By the way these areas on the bedrooms !!!
Can somebody give a suggestion on vapor barrier?
Where is the home? Code on vapor layers is code and area specific.
More information on the roof construction will be required as well.
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