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

[Benn Kilburn]

I would have to definitely lean towards using flashings as a default and
have been doing so now for several years.  Last project i wanted to use
flashings on and couldn't was in 2010.  I couldn't because it was a 10-13
deg slope with asphalt shingles that were really good quality and made for
low slope and resistant to high wind, this meant that each course of
shingle was very well adhered to the course below it, to the point that it
was next to impossible to lift the shingles to insert a flashing.  I tried
everything short of using a heat gun or torch to warm them up first.

I cannot quote anything, but i believe that there is an issue with voiding
roof warranties if you do not flash a penetration.

Always make sure that the sealant you choose is compatible with the roof
and any other material it will contact.  I believe there was an issue years
ago where many installers were using a popular "sealant" that (if you read
the small print) was not compatible with asphalt shingles.

My sealant of choice these days is Henry 925.

I would be very interested to see, if anyone would be willing to share (on
or off-list), photos of any signs of leaking or leak damage caused by
failed roof penetrations.

Cheers,
Benn


On Fri, Apr 11, 2014 at 1:20 PM, Troy Harvey <taharvey at heliocentric.org>wrote:

> 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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