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flashing for ribbed metal roof (5 Posts)
flashing for ribbed metal roofI have been looking for a way to mount collectors or racking on a delta rib metal roof. metal roof are common in this and many western areas. I have found a few options.
S-5 builds that arch Corru Bracket, shown here, for corrugated style roofing. Aztec builds the stainless gasket mount washers for different shapes.
I took the mini sample from Quick Mount PV trimmed it down and shaped it to fit on the rib.
The goal is to have the penetration seal at least 1/2" above the roof to eliminate leak potential. The Quick Mount system for shingle roofs puts the seal about .070 above the roof. On top of the delta rib it is up about 2".
Years agowe would use the classic Novan angle mounts and "glue and screw" them. In order to land on a flat section of roof we would install a 2x6 bundle between the roof joist in the attic. To prevent expansion contraction and dissimilar metals corrosion we would seal with butyl caulk and a 1/8" thick pad of vulcanized rubber sized slightly larger than the angle mount. Have also used the flexible master flashing's from Oatey with a fast jack style mount engineered for the load. Saw some cool stuff last summer at the Intersolar in Munich but it's not available in North America.This post was edited by an admin on July 15, 2013 10:51 PM.
all sorts of homemademount seals out there. I found that the S-5 folks have an adjustable bracket for the delta rib type metal roofs.
It's nice to find brackets and flashings that have some test or code compliant data with them. The roofing manufacturers are getting more concerned about improper penetration seals, and they may void warranties on the roofing product if not completed to their standard.
MountsI would be reluctant to attach a solar panel the the roof metal only. Roofs with exposed screws have holes in them anyway. The screws tend to elongate the holes in the metal as the panels expand and contract, creating a weak connection.
Standing seam roofs just have clips to hold the panels down, the panels are, by design allowed to slip up and down the roof.
I have seen ice dams pull entire metal sheets off roofs. Severe winds are also a concern. In new construction, mounting points that are bolted to framing and flashed into the roof work well. For retrofits, I would worry far more about securing the panel than leakage. Some of those connectors will work with lighter PV panels in forgiving climates. For heavier water filled panels I would only bolt directly to the framing.
my concerns alsoS-5 has done testing and has approvals for most of their products, not sure about this model.
I've yet to have a collector come loose, or off the roof, but I have seen a number of roof leaks caused by attachments and flashings.
Unless they are fastened to the structural members, like the rafters, the sheathing or metal is the weak link.