[RE-wrenches] Stanchions for Comp Shingle Roofs
jay peltz
jay at asis.com
Mon Sep 15 12:52:58 PDT 2008
I might only to add that use a lot of never-seize when you install the
2 part feet from Prosolar and unirack.
I like these designs, but they will corrode up and you'll never get
them apart in some years.
jay
peltz power
On Sep 15, 2008, at 10:19 AM, North Texas Renewable Energy Inc wrote:
> Wrenches,
> I have always used Peters #2 process. The reason being, in hot
> climates, asphalt shingles become very soft and susceptible to
> damage. We've all walked across one on a sunny >90f day. Anything
> mounted against one or more layers of 3 tab, and lagged firmly into
> a rafter, will compress the softened asphalt.
> So in the future, the flange that's flat against the shingles, is
> not as tight against the shingles as it would be if tourqued
> directly to the decking. And over the years, the minute movements of
> the stanchion and flange, from thermal stress, wood shrinkage, wild
> lift or load, will further compress the shingles under the
> increasingly loose fitting flange.
> Also, if a future roof pulloff & replacement is necessary, the
> entire array must be removed, including the standoffs. So when the
> new shingles are in place, all the mounting holes have disappeared.
> A complete array install is in order.
> It is indeed a little more work to mount directly to the decking but
> that's what sealant is for. I get barely 4 standoffs per tube. It's
> cheap insurance in my book.
> I also encourage every homeowner, during site surveys, to insist of
> others offering bids that flashing be used rather than angle
> aluminum brackets.
> Jim Duncan
> North Texas Renewable Energy Inc
> 4029 Aragon Drive
> Fort Worth, Texas 76133
> 817.917.0527
> ntrei at earthlink.net
> Serving North Texas since 1994.
> For more information www.ntrei.com
>
> ----- Original Message -----
> From: Peter Parrish
> To: 'RE-wrenches'
> Sent: Monday, September 15, 2008 11:28 AM
> Subject: Re: [RE-wrenches] Stanchions for Comp Shingle Roofs
>
> I’m not sure if we have discussed this before, but I would like to
> get opinions on the relative merits of the following two approaches
> to setting stanchions and flashing them in for a roof mounted PV
> system:
>
> Existing comp shingle roof in good condition. Professional Solar
> Fast-Jacks (or similar stanchions that result in a ¾” to 1” post to
> which to attach rails). I am not endorsing ProSolar products, I just
> wanted a specific example to work with.
>
> Approach #1: Lag stanchions directly onto existing comp shingle
> roof; cut a inverted “U” into the top layer of shingle; slip in
> Oatey-style flashing (9”x12”, with an elastomeric ring); seal
> exposed vertical edges of flashing with a bead of high quality caulk
> (Sika 1A)
>
> Approach #2: Remove shingles down to the felt; lag stanchion;
> replace shingles incorporating full-sized (15”x18”) flashing and
> seal top of flashing with high-quality caulk.
>
> Obviously, approach #2 takes longer and costs more, but does it
> confer commensurate benefit? If the resulting stanchion/flashing
> were exposed to the elements, I would tend to favor the latter
> approach; and if we were dealing with new construction the
> difference in time and money would not be significant. However, if
> the stanchion/flashing lies directly underneath a PV module, it will
> be shaded from the deleterious effects of UV sunlight and will not
> receive any direct rain or snow accumulation. Under these specific
> circumstances, I would argue that approach #1 should be more than
> adequate and last at least as long as an existing comp shingle roof.
>
> For those of you who haven’t seen the Fast-Jack/Oatey approach, you
> might want to look at http://www.prosolar.com/Oateys.htm.
>
> - Peter
> Peter T. Parrish, Ph.D., President
> California Solar Engineering, Inc.
> 820 Cynthia Ave., Los Angeles, CA 90065
> Ph 323-258-8883, Mobile 323-839-6108, Fax 323-258-8885
> CA Lic. 854779, NABCEP Cert. 031806-26
> peter.parrish at calsolareng.com
>
>
>
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