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Hi William;<br>
<br>
First, a sealed L foot is not a sealant only attachment system. It
has quite a bit of surface area beyond the hole just like a
flashing, and has mechanical attachment through the roof to the
structure (which a flashing often does not). I consider an L foot to
be a mini flashing for a mini penetration. Its relative. A
propanel screw has a 1/2" rubber washer for a 3/16" screw, and is
accepted by the roofing industry and IBC. A 2" x2" L foot base
with a 5/16" high strength lag and sealant is much more seal
relative to the penetration. A 12" x 12" flashing is used for
penetrations as large as 4" plumbing vents, and depends on the
rubber Oatey boot to seal, which most of us know will dry rot in
5-10 years. It's accepted by the roofing industry too, so I'm not
that impressed with the roofing industry's judgement to be honest.
I do agree, that overlapping layers so that gravity helps shed the
water is a good concept, but can't always be "adhered" to,
especially on metal roofs for instance.<br>
<br>
However, I will also mention that while I am comfortable with L
feet, and think they do meet code; I am considering flashings on my
next asphalt roof project. I've made many changes to my practices
over the years, not always because I though it was necessary, but
instead to "keep up with the Solar Jones". <br>
<br>
Have a good weekend,<br>
<pre class="moz-signature" cols="72">R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760</pre>
<div class="moz-cite-prefix">On 8/6/2015 1:53 PM, William Miller
wrote:<br>
</div>
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<div>Daniel:</div>
<div><br>
</div>
<div>Good question, and worthy of revisiting. </div>
<div><br>
</div>
<div>As a contractor and businessman, I am obligated to reduce
risk exposure by using best evolved practices. This requires I
used modern, purpose-built, approved attachment hardware. To my
knowledge, these are all flashed. </div>
<div><br>
</div>
<div>No roofing contractor will honor a warranty on sealant-only
attachments. On pitched roofs, gravity is the main factor in
shedding rain water and flashed systems accomplish this. </div>
<div><br>
</div>
<div>Thanks for bringing this up. </div>
<div><br>
</div>
<div>William<br>
<br>
<br>
</div>
<div><br>
On Aug 6, 2015, at 9:47 AM, Daniel Young <<a
moz-do-not-send="true" href="mailto:dyoung@dovetailsolar.com">dyoung@dovetailsolar.com</a>>
wrote:<br>
<br>
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<p class="MsoNormal">Writing the subject above, it seems
like I’ve heard this question on the wrench list before,
but I could not find it in my old email archives. Feel
free to pint me back to the old discussion if it’s there.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I’ve been using a flashing based roof
attachment for 8+yrs now (quick mount or similar). Now we
are looking at Rail-less systems (quick rack is a good
example). There is also a non-flashed rail-less racking
from roof-tech <a moz-do-not-send="true"
href="http://roof-tech.us/">http://roof-tech.us/</a> .
I’ve always been of the opinion that simply crushing some
sealant/gasket onto an asphalt shingle work fine at first
(the test data from roof-tech is impressive), but would be
an issue 10+yrs down the road (thermal expansion movement,
freeze/thaw, etc). I can make a good waterproof seal at
first by just slathering some butyl/silicone to an L-foot
and cranking it down on the shingles, but that practice
really disappeared 8+yrs ago.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Maybe consider this a Poll: (to flash,
or not to flash) <o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">With Regards,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Daniel Young, <o:p></o:p></p>
<p class="MsoNormal">NABCEP Certified PV Installation
Professional<sup>TM</sup>: Cert #031508-90<o:p></o:p></p>
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