[RE-wrenches] Flashing vs Sealant... again (is sealant code defensible?)

Sat Apr 19 14:42:25 PDT 2014

There should really be a distinction made between "penetration" and
"attachment."

A lag screw driven into a pilot hole with sealant pulling down a piece of
hardware specifically designed to sandwich the roof material is very
different than a loose pipe sticking up out of a hole in the roof. Sealing
lag screw attachment points is NOT analogous to sealing "penetrations" in a
general sense in my opinion. The attachment method and complete assembly is
part of the overall success in waterproofing an attachment point. For
example, I would not install a tall stand-off assembly using a sealant-only
method, because the leverage is too high and the base could work through
the shingle (a pliable surface) over time. Obviously pipes that are not
attached to the roof surface may move independently from the roof assembly,
and cannot be sealed with sealant along. Attachment points with pressures
that are generally normal (perpendicular) to the roof surface can be
successfully made with sealants.

One application where this has been proven out is solar pool heating, where
many of the attachment points for strapping have essentially no shear
pressures. It is completely cost prohibitive to attach a solar pool
heating system using metal flashings. Adding $1,000 to a $3,000
installation is not going to happen. The industry has proven that
sealant-based attachments, if done properly and with care, are a very
successful roof fastening method. The company I work for has made millions
of roof penetrations since 1974. If 40 years of success with sealant based
*attachments* isn't proof, I don't know what is!

I would like to see L-feet with larger bases that are round in shape for PV
installations without flashings. The closest I have seen is the Sunmodo
base plate, which is intended for use with a flashing and an L-Foot, of
course. Attached is a concept drawing that I think would work great.

[image: Inline image 1]

Jason Szumlanski

FAFCO Solar

On Sun, Apr 13, 2014 at 9:22 PM, Glenn Burt <glenn.burt at glbcc.com> wrote:

> In New York solar installations are required to have all penetrations
> flashed – chemical sealant is not flashing. An asphalt rooftop that sees
> temperature swings from -20 to 130F are a concern for simple thermal
> movement and I lost count of how many L feet I have seen with half a tube
> of silicone or worse yet Sikaflex goobered all around them. Ask any roofer
> what he thinks about drilling through the roof and relying on purely a
> chemical adhesive/sealant for the prevention of water intrusion, and he
> will laugh at you.
>
> NYS Building code 1503.2 is the primary reference for requiring flashing
> for all roof penetrations.
>
> The NYS 2010 residential code M2301.2.7, R903.2 all refer to ‘flashing’
> and sealing.
>
> The National Roofing Contractors Association provides guidance for asphalt
> shingles and penetrations.
>
> Checking with many roofing manufacturers also has shown that they require
> flashing penetrations to maintain their warranties – not using flashing is
> a violation of the roofing installation instructions…
>
>
>
> Yes it is more expensive – but it is like insurance, you don’t need it
> until you need it, but then there is no substitute for it. Of course if you
> are big enough with deep enough pockets you can take more chances with roof
> penetrations, and maybe you will not run into a call-back for a leaking
> roof. But if you do, wouldn’t you have a stronger position with the
> customer by saying all penetrations were flashed in accordance with
> standard roofing contractors and manufacturer’s specifications instead of
> ‘well I shot everything full of sealant and it is what I have been doing
> for years/hundreds of holes in roofs’…
>
>
>
> I can’t see in this day and age any reason not to use one of the many
> commercially available flashing solutions. Now 5 years ago, was a different
> time, and we formed our own flashing out of Al coil stock because there was
> no good solution available at that time.
>
>
>
> Hope this helps in your decisions…
>
>
>
> Glenn Burt
>
> One of many inspectors for the NYSERDA PV and Thermal incentive programs…
>
>
>
> *From:* re-wrenches-bounces at lists.re-wrenches.org [mailto:
> re-wrenches-bounces at lists.re-wrenches.org] *On Behalf Of *Troy Harvey
> *Sent:* Friday, April 11, 2014 3:20 PM
>
> *To:* RE-wrenches
> *Subject:* [RE-wrenches] Flashing vs Sealant... again (is sealant code
> defensible?)
>
>
>
> 1. I'm interest in a poll of installers who are using flashings vs
> sealant. Now that the flashing market has evolved, what are you using
> today? When did you switch to flashings (if you did). And why not, if you
> still prefer sealant.
>
>
>
> 2. Is there a any code defense for sealant systems ? (L-foot sealed down
> to shingles). Does anyone know of a scientific shootout between sealants
> and flashings?
>
>
>
> Here is my view: The construction industry is slow to evolve. Sealants,
> clauks & adhesives are not trusted in general, due to the legacy of code,
> and we have a mechanical vs. chemical industry bias.
>
>
>
> There is something about seeing a flashing that says, that is a
> "professional job", it must comply with code. And yet, my experience says
> I'd trust a 50-year silicone over a flashing that depends on gravity.
> Gravity should be dependable right? But anyone in snow country can tell you
> in spring, water can go uphill after ice dams form. There are high-rise
> buildings that use "structural glazing" which is just glass and silicone.
> These systems are now getting to be 50 years old without issue.
>
>
>
> The cost of flashings have come down in the last few years, but so has the
> cost per watt of installs. With 50 feet in a typical install around here
> that is $150 in feet, lags & silicone. Or $1500 in flashings, and extra
> labor. That can be a large part of a bid, and make you more expensive in a
> competitive landscape. That is fine, if it adds value... but I personally
> don't see the *proven* value, other than the "appearance" of code
> defensibility. Anybody have proof?
>
>
>
> thanks,
>
> Troy Harvey
> ---------------------
> Principal Engineer
> Heliocentric
> 801-453-9434
> taharvey at heliocentric.org
>
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