[RE-wrenches] Mounting to metal roofs and thermal expansion

[Troy Harvey]

> You don't screw the roofing pans down through the pan, they are all  
> held down with some kind of clip system; there are no roof  
> penetrations, as the hold down screws are under the roofing.

I'm not talking about seam clamps at all. But using a boot flashed  
stand-off foot.

We looked at S-5! clamps, but they aren't rated for many types of  
metal roofs. So we are going to use a Unirac stand-off foot lagged  
through the pan into the roof, with a rubber boot flashing. However,  
I'm concerned about the impact of fixing the roof in the middle of the  
pan with the lags on the foot constraining thermal expansion after  
seeing a European mounting foot system that they use a grinder to cut  
a hole in the metal roof, lag to the sheathing directly and use an  
overlapping rubber seal so the roof can move independently of the  
mounting foot.

Has anyone had problems with thermal expansion and mounting feet  
lagged through the roofing pan?


Troy Harvey
---------------------
Heliocentric
801-453-9434
taharvey at heliocentric.org