I built a 1000 (26 x 39) sq. ft. metal shop in back yard to replace a 24x24 wooden garage 40 years ago. About 5 years ago, the roof started to become a problem. First, the taping and aluminized paper that was effectively the vapour barrier failed and I got ice that melted in spring from condensation. About that time I think the washers on the screws (self drilling tek run into steel purlins) and in heavy rain I would get some leakage. Took the 6" rolls of glass fiber down and sprayed 5.5" of closed cell foam in its place, but now I need to keep water from entering any void between skin and foam. Will replace all of the fasteners tomorrow, but want to seal the seams to be extra safe. What is the best sealant to brush over the edges??
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Sealing metal roof
- Thread starter cannuck
- Start date
Youngandfree
Well-known member
I would replace the screws and use a roll or spray on rubberized coating like an RV roof over the entire thing.
I would replace the screws and use a roll or spray on rubberized coating like an RV roof over the entire thing.
Would the rubberized coating help keep the screws from loosening up?
Youngandfree
Well-known member
Have no idea. But they make industrial rubberized coatings for steel commercial buildings.Would the rubberized coating help keep the screws from loosening up?
cliffcharb
Well-known member
Can't help with product selection, but in order to prolong the metal roof (instead of replacement) on our commercial building we went with a coating. 5 year warranty, and 10 years later still holding strong. The roof was literally rusting in multiple places. It was about 1/3 the price of replacement.
Thanks for the suggestions. Will send a pic later, but rain this week stopped us cold in our tracks. Got some new screws with same size head (1/4"). The old ones were double start pointed (sort of self drilling IIRC) and the new ones are pointed single start - both 10ga, but the new ones are slightly larger in OD. The same size drive heads were important so we only need to take one tool each for remove and replace.
Still looking at what brush on stuff available for seams (we will NOT be lifting them as stuck to foam) but think some foam gone from ridge cap that we may have to replace with caulking before sealing.
Still looking at what brush on stuff available for seams (we will NOT be lifting them as stuck to foam) but think some foam gone from ridge cap that we may have to replace with caulking before sealing.
Firebrick43
Well-known member
NoWould the rubberized coating help keep the screws from loosening up?
Firebrick43
Well-known member
Yes, the screw design and material they are put into is what keeps them from loosening, a coating isn't going to help. I got about 15 years out of mine before they started leaking. My screws were ok so I just removed and installed a new box and then in the evening replace the washers on the ones I removed and repeat.None of my screws came loose over the last 39 years (OK, none of my BUILDING's screws did) but the rubber in the washers crumbled. I have been told they last about 20 years, and mine got over 30 before leaking.
As far as coating the seam, Ag panel seams don't typically leak by design but then they depend on ventilation on the back side which is now gone because of the spray foam. Did you have leaking seams or are you just worried about leaking seams?
Pretty sure all of my leaks were screw holes, and sadly I did NOT get them re-sealed when near end of a very long, very hot dry spell. Now more concerned with possible condensation from the tiny bit of air that could climb up and over the rib of lap joints.Yes, the screw design and material they are put into is what keeps them from loosening, a coating isn't going to help. I got about 15 years out of mine before they started leaking. My screws were ok so I just removed and installed a new box and then in the evening replace the washers on the ones I removed and repeat.
As far as coating the seam, Ag panel seams don't typically leak by design but then they depend on ventilation on the back side which is now gone because of the spray foam. Did you have leaking seams or are you just worried about leaking seams?
I feel your pain. I had one small leak and that started it all. I had to put in rescue screws (oversized) on my house metal roof. I should be good for another 25 years. It only took 2 days and about 2000 screws. mine were still in pretty good shape as far as the washers but, mostly a few loose ones. Good luck!