Questions about steel roof options for arched roof

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Joined: Thu Sep 14, 2017 4:36 pm

Thu Sep 14, 2017 9:41 pm

I have a 1970's trailer that has an arched roof. It's a very slight arch. I got Mark's book and it shows installing a steel roof on the same type of trailer. My questions are: What exact type of steel roof is that? How tall are the ribs? I have asked a few steel roofing providers and they say that their products require a 3/12 pitch. The arch on this roof is only about 1.5/12. From what I have read online, you should be using a standing seam roof, is that what Mark used?
Also, 1 steel manufacturer said his room needed 2/12 pitch unless you used butyl tape on the seams.


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Fri Sep 15, 2017 6:06 pm

With a domed roof such as yours there are no perfect roof over options.

I believe Mark used the basic 29 ga corrugated metal from any home store or you can order a better selection of colors from a quality lumber yard for about the same money.

I would use a sealer between the seams anyway just for insurance.

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Sun Sep 17, 2017 4:31 pm

There are a couple of problems with standard corrugated steel. All of the fasteners will need to be sealed with some type of roof sealant, polyurethane is a good choice. These fasteners will need frequent maintenance as expansion and contraction will loosen and tear sealants. Another problem is the height of the seam ribs. With any low slope, say less than 3/12, a hard down pour with driving wind can push the water into the seams.

While manufacturers instructions may warn against low slope roofs, this could be legaleeze for don't sue me and the product does not pass state code requirements for low slopes. Where low slope roofs often fail is where trusses are weak or age has made the eve edge of metal roofs stand up higher than the field of the roof, causing ponding. Very few coatings will tolerate water that does not go away quickly. They will most often wrinkle up and peel off. Liquid Rubber does tolerate ponding, by the way.

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All information and advice given is for entertainment and informational purposes only. The person doing the work is solely responsible to insure that their work complies with their local building code and OSHA safety regulations.