[RE-wrenches] Attaching Array To or Through Ply

Wed Mar 29 23:38:19 PDT 2023

Friends:

Thanks for bringing up this scenario.

I have two problems with using a product such as the easy-feet or other
deck-fastened brackets, particularly on a rigid foam-above-sheeting roof:

1.   I worry about compression of the foam material over time.  This could
leave a void under the bracket which could lead to leaks or wobbly brackets.

2.   I don’t believe in chemical solutions for sloped-roof rain-proofing.
By that I mean the use of caulks, gaskets, etc.  Since roofs were first
thatched, the overriding wisdom is that gravity is the only way to reliably
shed water.  Overlapping, seamless material is the only method to use.
Caulks degrade, roof surfaces become powdery, and the rafter is often under
an architectural feature or seam in the shingles.

I researched the PLP EZ foot back when the company was DPW.  The fasteners
provided were not rated for the application, according to the fastener
manufacturer.  If you can match the fasteners to the decking and the
forces, then maybe you have a start to a mounting solution.

Whatever product you use, I would install it on a section of flashing
metal, lapped under the next course up.  The flashing gives a flat,
seamless surface to caulk or gasket to.  The thicker and wider the
flashing, the more you distribute the downward force

applied to the bracket by weight and fasteners.  Any voids under the
bracket will have an overlapped flashing above it.

I hope these musings help you find a solution.

William Miller

PS:  I have encountered this roof configuration a few times on flat, built-up
roofing (BUR <https://homeinspectioninsider.com/built-up-roofing/>).  We
have dealt with it by cutting through the foam, installing blocking on top
of the sheeting and having a roofer feather the blocks into the roofing
with cant strips
<https://www.blueridgefiberboard.com/cant-strip-tapered-edge-smoothes-roof-drainage-slope/>.
A pitched roof is a different situation, however.

Wm

Miller Solar

17395 Oak Road, Atascadero, CA 93422

805-438-5600

www.millersolar.com

CA Lic. 773985

*From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *On
Behalf Of *August Goers via RE-wrenches
*Sent:* Wednesday, March 29, 2023 11:47 AM
*To:* RE-wrenches
*Cc:* August Goers
*Subject:* Re: [RE-wrenches] Attaching Array To or Through Ply

We've found that in the Bay Area that deck-mount solutions typically pencil
out structurally (via a structural professional engineer) as long as the
deck is 1/2" plywood or thicker, assuming we have all the info on how the
roof is constructed. The big assumption is that we can get all that roof
construction info, which can be difficult for existing structures.

We haven't taken the plunge yet on the flahingless deck mount products like
the Sunmodo Nanomount or Unirac Flashloc Duo. I do think that they offer
several significant advantages including not needing to find rafters, thus
virtually eliminating missed pilot holes, and not disturbing the comp
shingle by eliminating prying up the courses to insert the flashing.

August

Luminalt

On Wed, Mar 29, 2023 at 11:34 AM Solar Energy Solutions via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

We like Spider Rax… with the flashing!

*Spider-Rax PV Solar Mounting <https://spiderrax.com/>*

*spiderrax.com <https://spiderrax.com/>*

*Error! Filename not specified.* <https://spiderrax.com/>

*Andrew Koyaanisqatsi*

President

*Solar Energy Solutions, Inc.The BRIGHT CHOICE*

*Since 1987, helping you and your *

*Portland neighbors move towards an environmentally sustainable future.*

*503-238-4502 <503-238-4502>www.SolarEnergyOregon.com
<http://www.solarenergyoregon.com/>*

On Mar 29, 2023, at 11:04 AM, Jerry Shafer via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

Wrenches

Sounds like a SIP's type product, there are quite a few multi hole
attachment bases that are designed for SIP's. Most will have a larger base,
lots of holes for screws to attach that do not require rafters underneath
to attach.

Fun times

On Wed, Mar 29, 2023, 8:30 AM frenergy via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

Matt,

            I guess my questions are 1/2" plywood or 5/8" and how thick is
the foam?  Oh and I assume its nominal 2X6 T&G?  Do you know how the
plywood is attached?.....through the foam into the T&G?... to stringers,
nailers or whatever they're called?

Bill

Feather River Solar Electric

Bill Battagin, Owner

4291 Nelson St.(shipping)

5575 Genesee Rd. (USPS, UPS)

Taylorsville, CA 95983

530.284.1925 Office/ 530.258.1641 Cell

CA Lic 874049

Solar powered since 1982

On 3/29/2023 7:53 AM, Dave Tedeyan via RE-wrenches wrote:

Hi Matt,

I've used these in the past when on a comp roof and there was no good way
to get into the rafters (or TJI's in this case)

https://sunmodo.com/nanomount/

You might want to replace the screws with something shorter and beefier
though to get more grip if you are only going into 1/2" plywood.

Cheers,

Dave

On Wed, Mar 29, 2023 at 10:38 AM Matt Sherald via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

Hi All,

I've run into a roof-mounted job where the roof is built-up with the
following:

Comp shingle

Plywood

Foam board

T&G (roof deck, but also interior ceiling)

The beams that hold the t&g up are wide-spaced and not convenient for
fastening the full extent of the array.

This being the case, I was considering other fastening options and am
writing to pick the collective brain of the Wrenches to see how others have
addressed similar situations.

One thought I had was to use the PLP Easy Mounting Foot and I'd be glad for
any opinions on that or another solution.

-Matt

-- 

Matt Sherald

PIMBY Energy, LLC

304-704-5943

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