[RE-wrenches] Metal roof support flashing

[Laura Uhler]

Hi,

I talked with the roofer who gave the "Best Roofing Practices for PV" 
course at the NW Solar Expo, and at the Oregon Dept of Energy.  I then 
took his recommendation and ran it by two local roofing professionals, 
who similarly approved.  They recommended using the EternaBond "Tape" 
product.  It looks like a 1/4" thick pre-rolled roof caulking.  I get it 
in 2" wide rolls, or, you may be able to purchase it pre-cut.  (It's not 
cheap.)  You peel off the plastic outer layer and put it on the back of 
the L-feet.  I put on a double layer.  It becomes activated by pressure, 
so, when you screw your stainless steel lag bolts (with washers) into 
the underlaying rafters, the EternaBond will ooze up in to fill the 
cavity between the washer and oval L-foot hole.

I'd recommend that you allow yourself several hours to cut the 
EternaBond and pre-apply it to the L-feet before bringing the hardware 
on the roof.  That way, only the final layer of plastic needs be removed 
before screwing the L-foot onto the roof.  But, be warned, even with a 
top plastic layer on the "tape", the EternaBond will stick to 
everything!   There is no doubt that this is a much more solid, 
waterproof connection than the dollops on caulking around the six screws 
that must hold down every boot.

Good Luck!

Laura

-- 
Laura Uhler, Owner
Solar Ki, LLC
(541) 602-6909
laura.uhler at solarki.com
www.solarki.com




Kelly Keilwitz, Whidbey Sun & Wind wrote:
> 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 can't trust how the roof is held down.
>
> We want to install the supports to best roofing practices. The roofers 
> that we've 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 doesn't 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 don't 
> 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 'till 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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-- 
Laura Uhler, Owner
Solar Ki, LLC
(541) 602-6909
laura.uhler at solarki.com
www.solarki.com


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