Standing seam panels over purlins

Guest User
10/14/2013
I have seen architect-designed houses in the TX hill country on on which SS panels are installed on purlins, the purlins being 24" on centers over rafters spaced the same. Thus, when viewed from below in unconditioned areas such as roof overhangs and porches, one sees the grid of rafters and purlins, and the underside of the roofing panels. Here is the question. Is the Kynar-coated coil stock painted with the typical "wash coat over primer" arrangement of 1.5 mils primer and 3.5 mils of off-white finish? Because that is what I think I am seeing in these installations . . . a white finish on the underside of the pans. I ask this because the builder I have asked to quote a new house with this detail, is saying the bottom side of the roofing is some clear-only film and that my white look cannot be done without first laying white pans between purlins. Am a retired engineer, with a little long-ago experience in the biz, working almost 20 years in various capacities for one of the companies that now make up Centria. My first gig with them was as a construction superintendent, managing the crews that roofed the now-torn-down Cowboy Stadium near Dallas. On the multiple coil coating lines we had and which Centria now operates, a whole lot of the industry's coils are coated, and I remember the back side of most everything was a white polyester "wash" over the primer. So, is most all the residential SS stock white on the underside?
Todd Miller
Isaiah Industries, Inc.
10/15/2013
You will find that this varies from supplier to supplier and, frankly, some suppliers may not even be consistent in what they do. So, you will need to do some specification form your supplier to accomplish this. I generally am not a fan of residential installations without solid decking because they can lead to possible condensation issues. Good attic ventilation is important with this application. Of course, living in a very arid climate such as TX hill country helps as well.
Eric Novotny
An informed customer is the Best Customer!
10/15/2013
+1 to Todd's feedback. Be prepared for a noisier roof as well as compared to a solid deck.

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