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TOPIC: Product Selection

Galvalume vs SMP longevity

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We are installing a hidden fastener roof on our workshop. The roof is barely visible due to taller nearby buildings and cost is king. We are considering Ideal's Jr HF and ABC's SL16. Both are 29ga galvalume panels with an optional SMP paint. I am not concerned with color consistency over time - only longevity of the roofing for the money. Intuitively, it seems like the extra paint coating would add to the life of the panel (before oxidation can get to the steel, it has to get through galvalume AND polyester). Raw obviously saves money - does the SMP add significant life to the panel?

Somewhat related, I see lots "thicker the better" talk. How do concealed fastener systems typically fail that makes 29ga riskier? This is a fully sheathed deck - so puncture resistance seems irrelevant... I appreciate any insight!

Matthew Michaud

9/3/2018
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Sorry for the delay in answering your questions. Yes, any paint system will prolong the ultimate panel life. With clear acrylic coated panels, the acrylic is probably weathered away within 5 - 7 years, leaving just the corrosion resistant steel surface exposed to the weather. Exact performance will depend upon climate but I feel safe saying paint will double the life of the product. As far as metal thickness, I am much more about proper installation and good panel design than I am metal thickness. I'd look at whether metal thickness bumps up the wind rating on the panel and see how much that means to you in your climate. That said, thicker metal will be more puncture resistance and less prone to damage from foot traffic as well.

Todd Miller
Todd Miller
Isaiah Industries, Inc.

9/6/2018
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That response was well worth the wait. Thank you very much, that all makes a lot of sense.

Matthew Michaud

9/6/2018
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I agree with Todd about proper installation, which includes proper cutting of the metal. make sure a shearing action is being employed as opposed to a grinding or sawing. if not, this will lead premature failure along the cuts, regardless of the finish.
Also, the galvalume should have the AZ-50 coating weight to be used as a roofing product.

Dick Bus
Dick Bus

9/6/2018
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