I've dancing around the perimeter of this discussion but now wish to make that
one more not to flash. There are many ways to do any job. I have been
attaching things to roofs and cutting holes in roofs for a couple trades for 38
years and have yet to discover (or have a customer discover and contact me) any
damage from water. When attaching feet to a roof for a PV rail system, I do
not flash...I have but can't justify the time and cost for my perceived lack of
benefit. When I cut a hole in a roof, I flash.
I think its all about the correct caulking for the particular kind of
roofing material (one type does not fit all), proper preparation of the
attachment location, insuring there is plenty of wood for the fastener, laying
a liberal bead and proper torque of the fastener. $.02
Thanks,
Bill
Feather River Solar Electric
4291 Nelson St.
Taylorsville, CA 95983
530.284.7849 / 6544 fax
solar powered since 1982
From: Daniel Young
To: 'RE-wrenches'
Sent: Tuesday, August 25, 2015 2:19 PM
Subject: Re: [RE-wrenches] to flash or not to flash
Figured I would dig through the responses to this list topic since I posted
it as a poll, of sorts.
My final count was: 10 votes to flash, 4 votes not to flash.
Those who read all the responses probably know there are a few on either side
that would be OK with the other option.
I’m still on the flashing side of things, though I might consider letting the
client have a choice. If I explain the differences, and show them the $
difference, they can help make the decision (read that as? “take some liability
off of me J”). We do that now with US vs non-us made solar modules. It’s not
the same type of comparison here, but at least if the client really wants a
lower cost, they know how they’re getting it, and future calls from the client
should get tempered by the knowledge that they chose the attachment method.
Some really good points were raised on this topic, thanks to everyone who
participated.
With Regards,
Daniel Young,
NABCEP Certified PV Installation ProfessionalTM: Cert #031508-90
From: RE-wrenches [mailto:[email protected]] On
Behalf Of Jason Szumlanski
Sent: Monday, August 10, 2015 5:42 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] to flash or not to flash
Although my mind is kinda' made up, this thread has really got me thinking
and researching. I scoured the NRCA manual, which does not really define
"penetration," but it does say in the shingle manual:
"Penetration Flashings: There are many small penetrations that need to be
flashed into asphalt shingle roof
systems, such as vent pipes, exhaust vents, exhaust fans, furnace or water
heater flue pipes, electrical standpipes and others."
There is also a graphical figure showing these various penetrations. The one
thing these all have in common is that there is a substantial air gap cut fully
through the roof plane.
It occurred to me that ridge caps and vents on shingle roofs use exposed
fasteners to nail or screw them to the decking. The NRCA manual says about this:
"Exposed fasteners should be sealed with elastomeric sealant or asphalt roof
cement on the last ridge piece of a run, at the intersection of hips to a ridge
and at the intersection of a ridge to another plane."
Also read the Snow Guard section for metal roofs, which allows attachments
sealed to the flat part of the roof pan with sealants.
Until the manual specifically addressed the solar "attachments" and
"fasteners" we are debating about, it's open to interpretation.
On Fri, Aug 7, 2015 at 5:50 PM, Jason Szumlanski
<[email protected]> wrote:
http://www.oatey.com/brands/oatey/regions/canada/products/flashings/roof-flashings/retro-master-flash-roof-flashings
Well, the manufacturer calls it a flashing, but I agree that were talking
semantics here. Flashing, in the code sense, is applied liberally in practice.
The washers on the thousands of screws on a 5V metal roof must be flashings,
otherwise these roofs do not meet IBC, and would be prohibited, right? Same
goes for vents with screwed and sealed boots... Unless you don't call fasteners
penetrations, in which case you can't hold solar attachment fasteners to a
different standard. There are plenty of metal roof products that are sealed
(flashed?) with EPDM gaskets or butyl tape (Sunmodo, Eco-Fasten, S-5, etc.),
that are successfully implemented in real world scenarios.
There are really two issues here: clarifying what is acceptable from a code
perspective, and industry best practices. Martini shaken or stirred? We're
probably not going to agree on a single solution as an industry.
I have metal flashings on my shingle roof at home - it's my preference, but I
don't think it is a requirement, nor do I think "unflashed" fasteners are
completely unacceptable.
Jason
On Fri, Aug 7, 2015 at 5:11 PM, Kurt Johnsen <[email protected]>
wrote:
Not that the names of things matter that much but imho "flashing" does
require an overlapping of some kind. An Oatey boot for a metal roof is more of
a bedded fitting than a flashing. It relies entirely on fasteners and a sealing
membrane whereas flashings rely mostly on natural forces like gravity. Perhaps
an experienced roofer weigh in on this.
Kurt Johnsen
On Fri, Aug 7, 2015 at 3:21 PM, Jason Szumlanski
<[email protected]> wrote:
"If you place a flat object on top of roofing without an uphill material
lapping over the downhill object, you are not flashing. "
By that logic, an Oatey boot is not a flashing for a plumbing vent on a metal
roof.
Just sayin'...
Jason Szumlanski
On Fri, Aug 7, 2015 at 2:19 PM, William Miller
<[email protected]> wrote:
Ray:
I have to respectfully disagree with your semantics. A flashing is an
overlapping of roofing materials such that gravity will direct rain and melt
water off of the roof. This is a universally accepted waterproofing method
that does not depend on any sealant material. The concept is as ancient as the
first, crude, thatched roof.
If you place a flat object on top of roofing without an uphill material
lapping over the downhill object, you are not flashing.
What you have described is sealant-dependent weatherproofing. Regardless
of the quality of the sealant, or lack thereof, I don’t think you can call it a
flashed attachment.
(The overarching point is a flashed attachment does not depend on a
sealant. Any sealant has a finite lifespan. Removing the sealant variable
from the equation results in more lasting installation.)
Sincerely,
William Miller
Lic 773985
millersolar.com
805-438-5600
From: RE-wrenches [mailto:[email protected]] On
Behalf Of Ray Walters
Sent: Friday, August 07, 2015 10:34 AM
To: RE-wrenches
Subject: Re: [RE-wrenches] to flash or not to flash
My opinion is that if the L foot has enough surface area it constitutes a
flashing, and that large flashings can actually cause more damage to the roof
than they prevent.
I also agree that an attachement doesn't constitute a penetration. I just
finished an install on a metal roof with hundreds of screw holes. We added a
few more screw holes, and ours have 20 times the sealant surface area. We did
run a 1" conduit through the roof, and since it was an actual penetration, we
used a very expensive flexible boot flashing.
Personally, I think we need about a 3"x3" or 4" x 4" L foot with a double
stick butyl tape on the bottom, and all will be well.
I realize that the OP was referring to asphalt, but I will flash other roof
types that don't do well with L feet ( like shake).
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