Metal roof installation advice
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patrick_g
Elite Member
It is easy to over tighten a gasketed screw and it will leak there now or in the future. Properly torqued gasketed screws will seal really good now and leak later after the gasket deteriorates from sunlight, air pollution, movement from the metal expanding and contracting with temp changes, whatever. Never install corrugated or similar material by fastening in the valleys. My older but properly constructed 37x70 building leaked like a sieve till my wife and I spent two days on the roof sealing every suspicious fastener, replacing missing ones sealing suspicious seams etc.
Standing seam metal roofs cost more but are superior and worth the difference for a residence. Not only are the fasteners hidden from view after installation but they are so very very less leak prone which is important with drywalled ceilings. For a barn or shop you can take your chances with the cheaper process.
I was all set to go with a metal roof on the new house but found composition shingles rated so highly that I qualified for a 22% across the board discount on the homeowners insurance. (State Farm has a 28 page list of shingles so you can compare which are what for insurance purposes. It is available via the web)
I'm way ahead with my composition shingles. More expensive than typical shingles but way cheaper than a good metal roof.
Pat
Standing seam metal roofs cost more but are superior and worth the difference for a residence. Not only are the fasteners hidden from view after installation but they are so very very less leak prone which is important with drywalled ceilings. For a barn or shop you can take your chances with the cheaper process.
I was all set to go with a metal roof on the new house but found composition shingles rated so highly that I qualified for a 22% across the board discount on the homeowners insurance. (State Farm has a 28 page list of shingles so you can compare which are what for insurance purposes. It is available via the web)
I'm way ahead with my composition shingles. More expensive than typical shingles but way cheaper than a good metal roof.
Pat
Roto said:
You will see conflicting installation instruction from different manufaturers. Ideal from Quebec states screws in the rib. McElroy states in the flat, I think the old AluMax/Amerimax did as well.
As previously stated, follow the manufacturers instructions of the brand you've purchased and you should be in good shape.
patrick_g
Elite Member
With corrugated material I always have installed the wavy board that fits the contour of the roofing material and got a good result.
I have only done this sort of roofing job twice but with satisfactory results. There are foam plastic wavy board sort of gasket thingies that have a good water seal for the ends at the eaves.
Pat
I have only done this sort of roofing job twice but with satisfactory results. There are foam plastic wavy board sort of gasket thingies that have a good water seal for the ends at the eaves.
Pat
texasjohn
Super Member
Hmm... seems that Patrick_G's experience somewhat parallels mine... seems it takes a few years for the leaks to develop... but probability is there when using the valleys. So, the general consensus is.... follow instructions, hope, maybe move out of the house before the leaks start. Or go composition ....
well since my manufactorer says in the ribs that thats what i will do. The good thing about ribs is that its on the rib and cant leak much unless rain lands on that area but in the valleys your talking about 24 feet of rain water gushing down over the screw from above so i think ribs is the safer bet in the long run but i dont know.
My question to you guys is this: will 3/4 OSB be good enough to screw into with metal?
Mike
My question to you guys is this: will 3/4 OSB be good enough to screw into with metal?
Mike
tallyho8
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Roto said:
I have not seen any manufacturer recommend screwing in the rib on 29 gauge metal on roofs. If anyone has a manufacturers instruction sheet that shows this with 29 gauge metal would you please post it.
tallyho8
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I would not lay metal directly down on OSB without purlins. I believe this would cause a condensation problem on the OSB. Also, I do not believe the 3/4" OSB would sufficiently hold the screws.
patrick_g
Elite Member
I don't understand... Are you going to sheet the whole roof and then cover it with metal? Both my 25x70 metal shop bld and my pole (hay) barn (metal poles) have only the sheet metal roofing and no wooden sheet goods anywhere in the construction. The hay barn is similar in size but more square and is all corrugated galvanized steel on the roof and walls. The other bld is painted steel with the ribs and flats on both the roof and walls and it has no wood in the construction.
The hay barn has horizontal wooden stringers from pole (pipe) to pole to take fasteners to hold the walls on. It has 2x lumber between the horizontal pipe ridge pole and also between the pipe "rafters" and the corrugated galvanized steel roofing. Both buildings are at least 30 years old. On the hay barn they nailed through the boards and had the nails near the pipe and welded the nails to the pipe. May be a standard practice but I had never seen it before. My well house is of the same vintage and shares these construction details. Seems to work well. We are in tornado alley and the blds are 30+ years old with no wind damage.
The painted metal bld has spray on insulation. It is fire retardant cellulose and glue. The adhesion is failing and flakes and chunks, some large, are continuously falling off. All the buildings in this area of that era with that type insulaltion are having that problem. I met the guy who with his brother sprayed all these buildings. When their call backs started eating them alive and no consideration from the company who supplied the equipment, tools, materials, and training; they got out of the business and tried to look invisible for the next few years.
Do not volunteer to try an unproven method no matter what the price and how many others are doing it.
Pat
The hay barn has horizontal wooden stringers from pole (pipe) to pole to take fasteners to hold the walls on. It has 2x lumber between the horizontal pipe ridge pole and also between the pipe "rafters" and the corrugated galvanized steel roofing. Both buildings are at least 30 years old. On the hay barn they nailed through the boards and had the nails near the pipe and welded the nails to the pipe. May be a standard practice but I had never seen it before. My well house is of the same vintage and shares these construction details. Seems to work well. We are in tornado alley and the blds are 30+ years old with no wind damage.
The painted metal bld has spray on insulation. It is fire retardant cellulose and glue. The adhesion is failing and flakes and chunks, some large, are continuously falling off. All the buildings in this area of that era with that type insulaltion are having that problem. I met the guy who with his brother sprayed all these buildings. When their call backs started eating them alive and no consideration from the company who supplied the equipment, tools, materials, and training; they got out of the business and tried to look invisible for the next few years.
Do not volunteer to try an unproven method no matter what the price and how many others are doing it.
Pat
