This thread has morphed into more than it started as, and for good
reason. I want to provide some practical/anecdotal information, having
just gone through arguably the most catastrophic wind event in
Florida's history (Ian) since the boom in solar energy started, and
another major wind event (Irrma) just 5 years ago.
First, Aside from the Sunmodo and Quickbolt decking-only products, I
would check out IronRidge's new entrant into the market, the IronRidge
HUG. If you can't find info on it, ask your distributor or IronRidge
sales rep. They have data on truss attachments and also missed truss
installation procedures. It's a unique approach to a dual-purpose
product, and they did a stellar job on the engineering documentation
in my opinion.
Ok, now let's get to my most important point. Due to Hurricane Ian,
the number of roofing PV attachments that I have witnessed that failed
due to fastener pull-out (mine or competitors):
ZERO
The only building where we had any mounts fail was on a flat roof with
pitched panels and Anchor Products mounts on TPO membrane, but the
mounts themselves did not cause the failure. The roofing system itself
failed, causing a small section of the PV system to fail. But even in
that case, the following applies...
The weak point in a well-designed and installed system is not the
fastener or flashing system. The module to rail connection is where we
saw failures. These failures fell into a few categories:
* Windborne debris struck panel, panel frame failed, panel popped
out of mid-clamps.
* Catastrophic wind forces popped panels out of mid-clamps (a good
percentage of panels found INTACT and still functional on the
ground!) I suspect the panels became covex in the wind, bending
frames inward.
* Windborne debris struck mounting system components, panel
dislodged, often still on the roof suspended by DC leads.
* Mid-clamp t-bolt tore out of aluminum rail channel (IronRidge UFO,
Unirac SM).
* Mid-clamp sheared off (Quick Mount QRail).
* Unexplained module detachment failures.
On 9/28/22, while I stayed up all night bracing myself against my
front door that I thought was about to fail, I was imagining how many
roof leaks my clients were about to endure, and wondered about the
efficacy of my business going forward. Those fears never materialized.
Aside from a handful of minor panel dislodgements, there was no panic
following the storm (with respect to solar panels). The bigger problem
became all of the people needing to remove panels for roof
replacements, but PV panels largely protected roofs in the areas where
they were installed. Sadly, the rest of the roof often did not fare as
well.
Anyway, back to the decking attachments. I have been skeptical of
non-flashed products for comp shingle roofs for a long time. My
thinking is coming around, particularly with the HUG (I trust
IronRidge's testing regime). And sealants have come so far. This
method will remain up for debate probably for a long time. Around
here, I am pretty certain these products will outlast the shingles
they are placed upon. We only get 15 years out of most shingle roofs
around here.
About the pull-out fears... Mine are gone. We have done many flat
roofs with long fasteners through steel decking or wood decking. These
screws are usually something like #15 XHD screws in lengths from 5 -
12". Not a single failure. We have also used Quick Mount QBase
Low-Slope bases on pitched tile roofs that were only screwed into
decking with 4 fasteners each (due to horizontal truss transitions) in
some cases. Zero failures. But the most relevant attachments I can
think of that are germane to this discussion are the many thousands of
S-5 SolarFoot that we have screwed into decking on 5V metal roofs
around here. These have four screws per attachment, and S-5 load tests
show something like 240 lbs of pull-out strength in OSB (adjusted for
safety factor). When engineered for our wind loads, we usually get
anywhere from 36-48 inch attachment spacing, sometimes 24 inches in
certain roof zones. Again, not a single failure.
I have more solar installations on Sanibel Island and Fort Myers Beach
(Hurricane Ian Ground zero) than anyone. Many of those have
decking-only attachments, S-5 clamps, flat roofs, or other attachments
other than trusses. I can tell you unequivocally that I trust
decking-only attachments from a pull-out strength standpoint. When
properly engineered, with cautious attachment spacing, these mounts
work in both OSB and plywood. Because of the inconsistencies in OSB,
we always err on the side of caution, if not in the engineering, then
in the installation, by installing more attachments than prescribed.
But the evidence is clear. It works.
Caveat to the above: I have zero experience with snow or seismic, and
no experience on roofs exceeding 8:12 pitch, and few above 6:12.
And one more shout-out to S-5 clamps on standing seam roofs. Aside
from one minor failure of the roof metal itself, not an S-5 failure,
we had zero failures of S-5 clamps attachments to report.
I hope this anecdotal information helps and sets some fears aside.
Please reach out to me off-list if you want any specifics or details
about our experience with catastrophic wind events.
Sincerely,
Jason Szumlanski
Principal Solar Designer | Florida Solar Design Group
NABCEP Certified Solar Professional (PVIP)
Florida State Certified Solar Contractor CVC56956
On Thu, Mar 30, 2023 at 2:47 AM William Miller via RE-wrenches
<re-wrenches@lists.re-wrenches.org> wrote:
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 <http://www.millersolar.com/>
CA Lic. 773985
*From:*RE-wrenches
[mailto:re-wrenches-boun...@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@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 <tel: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@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@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@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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