[RE-wrenches] to flash or not to flash

Mon Aug 10 02:42:23 PDT 2015

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 <
jason at floridasolardesigngroup.com> 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 <kjenergysystems at gmail.com>
> 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 <
>> jason at floridasolardesigngroup.com> 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 <
>>> william.miller at millersolar.com> 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
>>>>
>>>>
>>>>
>>>>
>>>>
>>>> [image: Gradient Cap_mini]
>>>> Lic 773985
>>>> millersolar.com <http://www.millersolar.com/>
>>>> 805-438-5600
>>>>
>>>>
>>>>
>>>> *From:* RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] *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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