Metal roof insulation to fix condensation

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Picalilli

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I’m leaning more towards this idea of going in from the top and putting insulation in from above and replacing the existing corrugated roof. It’s in pretty good condition.
What’s the benefit of the spacer bars and brackets? The sheets already rest on the beams in place so presumably I could just board up with osb from below and then lift the sheets from above and put insulation in? Just wondering, what kind of space should be between the insulation and the corrugated sheet? Does it matter if the insulation touches it or should there be an air gap?

I’m actually wondering if I should insulate the walls too and make it more of a space I could heat up efficiently if working in there.

Lots to consider!
 

jrm688

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You need to keep the humid air away from the cold steel. A closed cell spray foam is an excellent choice. It would give you both the vapour barrier and thermal insulation. My second choice would be the rockwool with a sealed vapour barrier on the warm side. Don’t be afraid of the rockwool, it is not picky like fibreglass.
 

mg123

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I've have a galvanised roof and had the same problem. My beams are 8x2 so I put in 50mm polystyrene between them and covered over with that bubble wrap foil and made sure every joint was well taped up and sealed. I then battened over and covered with ply. I kept an air gap above the polystyrene from end to end to hopefully prevent issues. My only concern is that I now can't see if there is any moisture trapped up there so the effectiveness remains to be seen.
The walls and flooring are also insulated, sealed and boarded over. The external walls are medium density blocks. I also have a set of double glazed doors so it should be a well sealed box. The temperature is generally a couple of degrees higher than outside. It's very rarely heated, maybe 2/3 days a month during colder days.
 

baldkev

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i looked into spray on insulation for my shipping container.... its actually quite expensive
 

DennisCA

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I think your original plan seems sound, though if you use rockwool, then opt for a moisture barrier.
 

Hornbeam

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Upgrading single skin metal roofs seems to be a a fairly common subject on this forum. My day job is as a technical engineer for metal roof and wall cladding. It is difficult to give advice without seeing exactly what a building is like, but from your i,mages it looks like the interior is in good condition and teh structural timbers are fairly substantial.
I would not recommend spray foam for numerous reasons but it is fairly popular on the other side of the pond, nor would I enclose the timber beams as you would not be able to see any rot developing.
You could strip off the xisting sheeting and replace with OSB but you are adding cost and work. (OSB will give slightly better sound absorption due to increased mass.
The spacer bracket and bar system I recommended in my earlier post is to hold a cavity to take the insulation quillt. Glass wool is much easier to handle than rock wool due to the longer fibre length (more of an issue on walls.
See the 2 links below for some details. Any questions, drop me pm and I will get back to you
Ian
 

Blaidd-Drwg

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I live in a colder climate (minus 31 fahrenheit this morning) but I have a pole barn with a metal roof and have closed cell foam insulation up on the ceiling. This acts as a vapor / moisture barrier and as insulation. I've been very happy with this so far, but it may not work in your climate.
 

Picalilli

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Upgrading single skin metal roofs seems to be a a fairly common subject on this forum. My day job is as a technical engineer for metal roof and wall cladding. It is difficult to give advice without seeing exactly what a building is like, but from your i,mages it looks like the interior is in good condition and teh structural timbers are fairly substantial.
I would not recommend spray foam for numerous reasons but it is fairly popular on the other side of the pond, nor would I enclose the timber beams as you would not be able to see any rot developing.
You could strip off the xisting sheeting and replace with OSB but you are adding cost and work. (OSB will give slightly better sound absorption due to increased mass.
The spacer bracket and bar system I recommended in my earlier post is to hold a cavity to take the insulation quillt. Glass wool is much easier to handle than rock wool due to the longer fibre length (more of an issue on walls.
See the 2 links below for some details. Any questions, drop me pm and I will get back to you
Ian
Thanks very much for the detailed help. I think I have an idea of what I want to do now but may post you a message explaining a bit more to see if I’m understanding you correctly.
 

thetyreman

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organic sheeps wool is expensive but supposedly very good the downside is the expense, rockwool is safe as long as you use common sense, gloves and a mask, fibreglass however I'd avoid.
 

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