[RE-wrenches] Metal roof support flashing

[Kelly Keilwitz, Whidbey Sun & Wind]

Wrenches,

We install PV & SHW on a lot of flat-pan metal roofs here in the Great
Northwest. Most of these roofing seams are not amenable to S-5! clips ­ and
if they are we can¹t trust how the roof is held down.

We want to install the supports to best roofing practices. The roofers that
we¹ve worked with use rubber boots that fit over vents and holes, which seal
to the roof with goop and are attached by screwing through the ring at the
base of the boot, through the roofing, into the roof sheathing.

The flashing boot around the post requires 5 to 9 more screw holes,
depending on the diameter and doesn¹t conform around the standing seams very
well. Additionally, on roofs with no full sheathing deck ­ like with skip
sheathing, and horizontal perlins - the boot cannot attach to the roof very
securely. 

Although this seems necessary for situations where there is an actual object
going through the roof (e.g. conduit, pipe, and vents), I don¹t see how
flashing this way will be better than simply using posts without the boot
flashing, or even L-feet, direct to the roof, with an EPDM gasket, with one
or two lag bolts predrilled into the roofing truss or perlin, and filled
with goop Œtill it squirts out.

What do you do on metal roofs in these situations?

Thanks,

Kelly Keilwitz, P.E.
Whidbey Sun & Wind, LLC
Renewable Energy Systems
NABCEP Certified PV Installer
WA Electrical Administrator #KEILWKM923RB
987 Wanamaker Rd.
Coupeville, WA, 98239
360.678.7131
sunwind at whidbeysunwind.com
WA Electrical Contractor #WHIDBSW920MS
WA General Contractor #WHIDBSW946M1



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