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TOPIC: Product Selection

24 or 26 ga galvalume without striations & oil canning

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I'm currently building a house in the north georgia mountains and the roofing contractor is wanting me to sign an oil canning waiver because he was installing a 26ga, 16", 1.5" standing seam, flat roof panel. He wanted to install with striations but we don't like the look.

Is 26ga just a bad idea? How much oil canning would be expected?

Should we just pay the increase to 24ga to reduce the likelyhood of this happening? What would you expect the price premium to be?

Thanks in advance.
mysterytour2000

2/7/2019

I am sorry ... not sure on the price difference but my gut feeling is they will want you to sign a waiver regardless of metal thickness if there are no striations. The risk of oil canning is exacerbated by a lot of things on the job site but it also can just be related to the metal itself. There really is no definitive way to predict what it will be like. You might ask the contractor if they have ever used backer rod behind the panels. This puts a little "crown" in the flat of the panels, which can help to take up or absorb any excess metal or metal stresses that would otherwise result in oil canning.
Todd Miller
Isaiah Industries, Inc.

2/7/2019

Oil canning is much a function of the deck as it is of the metal.

How good is the existing roof deck?
Eric Novotny
An informed customer is the Best Customer!

2/7/2019

It's brand new roof decking and appears to be good. Rafters are 2x10. Closed cell foam will be sprayed directly below the roof deck.
mysterytour2000

2/7/2019

Thank you for the response. I've never heard of putting a backer rod below the panel, but that makes a lot of sense.
mysterytour2000

2/7/2019

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