[RE-wrenches] L feet no flashing in shingle roof

[Chris Mason]

I don't believe you are correct here. The body of the lag does not do
anything for the holding power, it is the threads that prevent pullout. If
you drive a 5/16 lag into a 3 x 8 without a pilot hole, you will be putting
a lot of pressure into the wood to split it. It might not split every time,
it might not split right then, but you are definitely introducing a lot of
stress for no good reason. On any of these techniques for mounting, I want
to follow the manufacturers recommendations, otherwise how can you be sure
if you are right. Without a testing lab, you have no way to know.
I think mounting PV systems IS a science project, it takes care and thought
to do it right. We do a lot of concrete roof installations in hurricane
areas, and mounting keeps me up at night.


On Sun, Jul 1, 2012 at 9:13 PM, <mark at hurshtown.com> wrote:

> In my 20 year experience of lagging down L feet on shingle roofs in
> Indiana with a good dollop of silicone caulk under the foot, I've never had
> an issue.  No pre-drilling, just drive the lag home.  Drilling a hole first
> is not necessary, and reduces holding strength.  No reason to make a
> science project out of it and increase cost and labor.
>
> Mark
>
>  -------- Original Message --------
> Subject: Re: [RE-wrenches] L feet no flashing in shingle roof
> From: Drake <drake.chamberlin at redwoodalliance.org>
> Date: Fri, June 29, 2012 3:09 pm
> To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
>
> Hi Jay,
>
> There is no room for flashings.  The L feet will go very close to the
> skylights and the flashing would hit the edge of them.   Plus there is an
> existing array that was done by another installer that is done with L feet
> only.  The new array would be higher.
>
>
> And given that we have really good off the shelf approved flashed feet,
> why would you use anything else?
>
> My 2 cents,
>
> Jay
>
> peltz power
>
>
> On Jun 29, 2012, at 5:16 AM, Glenn Burt wrote:
>
> We have used a variety of sealants over the years, and determined simple
> Henry roofing cement is the best product for use on comp roofing.
>
> We also used to bend our own L-foot flashing, which we cut from standard
> Al coil stock (before all the manufactured options were available). This
> might be a good option for you in this case.
>
>
>
> Glenn
>
> *From:* re-wrenches-bounces at lists.re-wrenches.org [
> mailto:re-wrenches-bounces at lists.re-wrenches.org<re-wrenches-bounces at lists.re-wrenches.org>]
> *On Behalf Of *Drake
> *Sent:* Thursday, June 28, 2012 6:40 PM
> *To:* RE-wrenches
> *Subject:* [RE-wrenches] L feet no flashing in shingle roof
>
> I'm quoting a job that has an existing array with L feet bolted down to a
> shingle roof with no flashings.  I want to match the height of the existing
> array.  Also some modules are being worked in around skylights where it is
> unlikely that room would be available for flashings to center over rafters.
>
> I've always used flashings.  Would it be completely crazy to follow suit
> of the existing array and bolt L feet straight to the shingle roof with
> good roof sealant?  If so, how would you seal it?
>
> **
> Drake Chamberlin**        **
> ATHENS ELECTRIC LLC
> OH License 44810**        **
> CO license 3773
> NABCEP Certified PV
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-- 
Chris Mason
President, Comet Systems Ltd
www.cometenergysystems.com
Cell: 264.235.5670
Skype: netconcepts
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