Metal roofing on a shed...sheet and ridge cap installation?
June 22, 2008 2:36 PM   Subscribe

I'm nearly the end of my first major building 8'x8' shed with a foot overhang on all sides. I've just put up the trusses (purchased them, with a 4 in 12 pitch) and put 3/8" plywood on top. A neighbour gave me a whole bunch of metal sheet roofing in 12' lengths that I will cut down to length. My question is...he didn't give me a ridge cap and I have no idea what to buy or how to install that. Advice please? FWIW, I'm not 100 clear on the metal sheet installation either, so help there is appreciated too. Please keep in mind that this is just a shed and I don't expect anything even close to perfection! Thanks!
posted by Kickstart70 to Home & Garden (7 answers total)
"I'm not 100 clear" = "I'm not 100% clear"

Not sure what happened to my percentage mark.
posted by Kickstart70 at 2:40 PM on June 22, 2008

You can buy nails that have a rubber ring on them, which you nail through the sheet metal into the plywood (which seems quite sturdy for such a shed, but that's ok). Some people bend a ridge cap out of leftover sheet metal, but I'm sure you could buy one.
posted by OmieWise at 3:30 PM on June 22, 2008

Easiest solution would just be to extend the sheetmetal a few inches above the ridge on one side & bend it over. You might run into problems with repair & replacement though. You'll install it the same way you put the sheet metal onto the plywood - going through two pieces isn't really any harder. Just make sure it's anchored into the plywood well. You don't need to anchor it in many spots, though, and actually, you might not want to, again to make repair/replacement easier. Using screws would be one option.
posted by devilsbrigade at 3:44 PM on June 22, 2008

If you haven't gotten a solution yet, has a forum where you can ask questions of the head guys of the metal roofing industry.
posted by metajc at 7:24 PM on June 22, 2008

I helped a guy from the Catskills put a metal roof on once. He had been doing it for years but was more of a handy man and not a roofer.

He special ordered everything at an agway.

We used screws with those rubber rings on them. We carefully screwed them in the raised ridges so they wouldn't deform the metal. His thought on this was that the water runs down below the ridges so the screws don't get too leaky. After doing this roof I looked at other metal roofs and noticed few were done this way. I have no idea which is correct.
posted by bdc34 at 7:45 PM on June 22, 2008

Roofing screws (with seals) go on the high part of the sheet profile, yeah. If you've seen it any other way, it's wrong - a typical handyman mistake.

You should be able to buy lengths of ridge capping to suit whatever profile the sheet is - flat, corrugated, square corrugations, some other funky decorative profile, etc - at the same places you buy roof sheeting. In metric countries it's sometimes hard to find ridge caps to match old imperial-sized sheeting, but that's probably not a problem in the US.

Personally, I wouldn't put ply under metal sheeting. All roof sheeting leaks/weeps to some degree, not necessarily enough to cause drips or anything, just damp; all ply is gonna do is hold it there and create a high humidity environment for the ply to rot or metal sheeting to rust.
posted by Pinback at 8:11 PM on June 22, 2008

Most of the major sheet roofing manufacturers would have installation manuals online (">example)
where you would be able to find information regarding your specific profile and required fixings, batten spacings, accessories etc.
2nding Pinback - depending on the climatic conditions where you are, changes in indoor/outdoor temperature will cause condensation to form on underside of metal sheeting; good ventilation is important.
posted by beige at 6:28 AM on June 23, 2008

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