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Jason, thanks for the comment! I agree that systems could connect to
just sheathing and stay on the roof- I think Zilla has a product
that does this too. My concern about wind resistance stems from the
fact that there appeared to be an engineer's stamp on the Unirac
calcs with lag screws and then something completely different was
installed in the field. It's likely that this installer has used
this same mounting system in windier coastal areas so hopefully
their fastener selection had some informed analysis... I didn't see
any, though.<br>
<br>
And to be clear, I'm not looking to overrule another PE if it is in
fact an engineered system and it's just that the wrong set of plans
got submitted to the building department.<br>
<br>
DKC<br>
<br>
<br>
<br>
<div class="moz-cite-prefix">On 2014/6/3, 10:12, Jason Szumlanski
wrote:<br>
</div>
<blockquote
cite="mid:CAJJtG3rpuVxygg1_VQycvp=BZD4jcmRyn9U0HHuoXZ15eq+1iw@mail.gmail.com"
type="cite">
<div dir="ltr">
<div class="gmail_default"
style="font-family:verdana,sans-serif">Dave,</div>
<div class="gmail_default"
style="font-family:verdana,sans-serif"><br>
</div>
<div class="gmail_default"
style="font-family:verdana,sans-serif">
I can't identify your hardware, but I just wanted to comment
on your comment about hitting rafters. There are products out
there that can obtain the requisite load ratings without
connecting directly to structural members. We have had systems
engineered and permitted using Ecofasten products on low-slope
roofs that fasten only to wood sheathing or metal roof
materials in 170 mph zones in Florida (ASCE 7-10, FBC 2010).
I'm not an engineer, but I've been told if there is adequate
data on pull-out and shear, you can use that data to properly
design a system without hitting rafters with the right number
of attachment points. I don't like the looks of what you
pictured, but it's plausible that it was an engineered system
design. The permit drawings not matching... that is another
story...</div>
<div><br>
</div>
<div>
<div class="gmail_default"
style="font-family:verdana,sans-serif">If, for example,
each of the six fasteners provide 100 pounds of pullout
strength with a safety factor, that would be good for 12 sq
ft at 50 spf uplift per attachment. 250 fasteners would be
good for about 5kW of solar.</div>
</div>
<br>
<div id="WISESTAMP_SIG_gmail_session"
href="http://WISESTAMP_SIG_gmail_session">
<div
style="font-size:13px;font-family:Verdana,Arial,Helvetica,sans-serif">
<div style="margin:0 0 8px 0">
<p style="margin:0"><span><span>Jason Szumlanski</span></span></p>
<div class="gmail_default"
style="font-family:verdana,sans-serif;display:inline">
Fafco Solar</div>
<br>
</div>
</div>
</div>
<div class="gmail_extra"><br>
<div class="gmail_quote">On Tue, Jun 3, 2014 at 9:06 AM, Dave
Click <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:daveclick@fsec.ucf.edu" target="_blank">daveclick@fsec.ucf.edu</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Hi all,<br>
<br>
Anyone know what this racking system is? The permit
drawings say Unirac with lag screws and Eco-Fasten
flashings, which this pretty clearly isn't. I'd never seen
this before, and I imagine this wind resistance is not
quite the 140 mph that the installer claims it is. Of the
~250 wood screws holding this system down into the roof, I
think six of them accidentally hit rafters.<br>
<br>
Thanks!<span class="HOEnZb"><font color="#888888"><br>
Dave<br>
</font></span></blockquote>
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