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Trusses</title></head><body>
<div>Hi Drake and all,</div>
<div><br></div>
<div>We have had both engineers and inspectors question the use of a
3/8" 4" lag in a 2x4 top chord and I think rightfully so.
When we have a chance to spec new construction we have the architect
replace the 2x4 top chord with a 2x6.</div>
<div><br></div>
<div>And when we have to go into 2x4's we either shorten our lag to a
5/16" 3.5" or even 3" (if we can get away with it on
the uplift calcs) so we stay in the top half of the wood fibers on the
truss. We have also sistered or blocked 2x4s when there
was concern.</div>
<div><br></div>
<div>But like Bruce said - I cannot imagine there ever being a problem
with a 2x6 with a 4 " lag (only 3.5" of which goes into the
wood) unless you were using 1/2" lags!</div>
<div><br></div>
<div>The real issue is in installation. Installing a lag so that
it glances the side and splits the rafter or hitting a knot and not
backing off could cause problems. So we are really careful in
installation to make sure we are right on the center of the truss - we
drill tiny probes everytime - that's where the real issue is - once
engineering is happy of course.</div>
<div><br></div>
<div>Hope that helps!</div>
<div><br></div>
<div>Jeff Clearwater</div>
<div>Village Power Design</div>
<div><br></div>
<div><br></div>
<div><br></div>
<div><br></div>
<div><br></div>
<blockquote type="cite" cite>Our Building Dept requires PE sign-off on
all roof-mounts, so our engineer has evaluated a few trusses for us,
and has never brought up an issue about lags. I'll ask him what he
thinks about this. Most trusses are built all of 2x4's but some we've
seen have 2x6 top chords, which are reassuring to see. If you are
using something like QuickMounts, which typically use 5/16" lags
or hanger bolts, and you have 2x6 material to penetrate, it's harder
to imagine it could be an issue, than 3/8" lags into 2x4's. If
you're having trusses built for new construction, your could try
specifying 2x6 top chords from the truss co.<br>
<br>
Bruce Erickson<br>
Mendocino Solar Service<br>
707-937-1701<br>
707-937-1741 fax<br>
PO Box 1252<br>
Mendocino, CA 95460<br>
<br>
<br>
<br>
"Serving the Solar System"<br>
<br>
<br>
<br>
<br>
<br>
On Apr 27, 2010, at 8:50 AM, Max Balchowsky wrote:<br>
<br>
> When we talked to a manufacturer they wanted us to put supporting
lumber on top of the roof to support the array rather than penetrate
the truss with a lag bolt every 4'. We tried to get them to accept a
"drill through" and a bolt with a fender washer. We
abandoned the project.....<br>
><br>
> Max Balchowsky<br>
> SEE Systems<br>
> 1048 Irvine Ave Suite 217<br>
> Newport Beach Ca. 92660<br>
><br>
> 760-403-6810<br>
><br>
><br>
><br>
> ----- Original Message ----<br>
> From: Richard L Ratico <Richard.L.Ratico@VALLEY.NET><br>
> To: re-wrenches@lists.re-wrenches.org<br>
> Sent: Tue, April 27, 2010 7:27:08 AM<br>
> Subject: Re: [RE-wrenches] Lags & Trusses<br>
><br>
> Wow, this could be a hairball. Needless to say, we've all
probably already done<br>
> this, more than a few times. But....as a former carpenter....
though claiming no<br>
> expert truss knowledge, my sense is that the top chord of the
trusses should be<br>
> in compression. Therefore, a 3/8" diameter lag, for
instance, would substitute<br>
> steel for wood in compression, not a bad move. The trusses should
be very well<br>
> braced laterally by the roof deck. I don't see the problem.<br>
><br>
> Is the new roofing material being applied over existing roofing,
applying<br>
> additional load? Are there circumstances that make this a special
truss<br>
> application, cantilevers, slate roofing, etc.?<br>
><br>
> It would be interesting to talk directly with the manufacturer,
to get their<br>
> entire scoop on the project. It may be an overly-cautious
approach to liability<br>
> concerns. If starting from scratch, the truss manufacturer should
be able to<br>
> design for whatever the application requires. Sistering boards to
their trusses<br>
> might easily freak them out as well. Ask them what they would
suggest. There are<br>
> lots of truss manufacturers if this one can't handle the job.<br>
><br>
> Dick Ratico<br>
> Solarwind Electric<br>
><br>
><br>
> --- You wrote:<br>
> Hello Wrenches,<br>
><br>
> I just talked to a carpenter, who we are installing an array
for. He<br>
> is putting a new roof on the building and was talking to the<br>
> manufacturer of the trusses. He mentioned that he was
having an</blockquote>
<blockquote type="cite" cite>> array installed on the roof.<br>
><br>
> The truss manufacturer said there were problems with weakening
the<br>
> truss structure with the lag screw penetrations. We are now
planning<br>
> to sister boards next to his trusses instead of penetrating
them.<br>
><br>
> Does this seem like a potential issue? Is there any data on
this?<br>
><br>
> Thanks,<br>
><br>
> Drake<br>
><br>
><br>
> Drake Chamberlin<br>
> Athens Electric<br>
> OH License 44810<br>
> CO License 3773<br>
> NABCEP TM Certified PV Installer<br>
> Office - 740-448-7328<br>
> Mobile - 740-856-9648
_______________________________________________<br>
> List sponsored by Home Power magazine<br>
> --- end of quote ---<br>
> _______________________________________________<br>
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</blockquote>
<blockquote type="cite" cite>Our Building Dept requires PE sign-off on
all roof-mounts, so our engineer has evaluated a few trusses for us,
and has never brought up an issue about lags. I'll ask him what he
thinks about this. Most trusses are built all of 2x4's but some we've
seen have 2x6 top chords, which are reassuring to see. If you are
using something like QuickMounts, which typically use 5/16" lags
or hanger bolts, and you have 2x6 material to penetrate, it's harder
to imagine it could be an issue, than 3/8" lags into 2x4's. If
you're having trusses built for new construction, your could try
specifying 2x6 top chords from the truss co.</blockquote>
<blockquote type="cite" cite><br></blockquote>
<blockquote type="cite" cite>Bruce Erickson</blockquote>
<blockquote type="cite" cite>Mendocino Solar Service</blockquote>
<blockquote type="cite" cite>707-937-1701</blockquote>
<blockquote type="cite" cite>707-937-1741 fax</blockquote>
<blockquote type="cite" cite>PO Box 1252</blockquote>
<blockquote type="cite" cite>Mendocino, CA 95460</blockquote>
<blockquote type="cite" cite> </blockquote>
<blockquote type="cite" cite><br>
<img src="cid:p06240806c7fce955e8e9@[192.168.1.3].1.0" width="135"
height="132"><font face="Papyrus" color="#F2962D"><br>
"Serving the Solar System"</font></blockquote>
<blockquote type="cite" cite><br></blockquote>
<blockquote type="cite" cite><br></blockquote>
<blockquote type="cite" cite><br>
<br>
</blockquote>
<blockquote type="cite" cite><br></blockquote>
<blockquote type="cite" cite>On Apr 27, 2010, at 8:50 AM, Max
Balchowsky wrote:</blockquote>
<blockquote type="cite" cite><br>
<blockquote type="cite" cite>When we talked to a manufacturer they
wanted us to put supporting lumber on top of the roof to support the
array rather than penetrate the truss with a lag bolt every 4'. We
tried to get them to accept a "drill through" and a bolt
with a fender washer. We abandoned the project.....<br>
<br>
Max Balchowsky<br>
SEE Systems<br>
1048 Irvine Ave Suite 217<br>
Newport Beach Ca. 92660<br>
<br>
760-403-6810<br>
<br>
<br>
<br>
----- Original Message ----<br>
From: Richard L Ratico <<a
href="mailto:Richard.L.Ratico@VALLEY.NET">Richard.L.Ratico@VALLEY.NET</a
>><br>
To: <a
href="mailto:re-wrenches@lists.re-wrenches.org"
>re-wrenches@lists.re-wrenches.org</a><br>
Sent: Tue, April 27, 2010 7:27:08 AM<br>
Subject: Re: [RE-wrenches] Lags & Trusses<br>
<br>
Wow, this could be a hairball. Needless to say, we've all probably
already done<br>
this, more than a few times. But....as a former carpenter.... though
claiming no<br>
expert truss knowledge, my sense is that the top chord of the trusses
should be<br>
in compression. Therefore, a 3/8" diameter lag, for instance,
would substitute<br>
steel for wood in compression, not a bad move. The trusses should be
very well<br>
braced laterally by the roof deck. I don't see the problem.<br>
<br>
Is the new roofing material being applied over existing roofing,
applying<br>
additional load? Are there circumstances that make this a special
truss<br>
application, cantilevers, slate roofing, etc.?<br>
<br>
It would be interesting to talk directly with the manufacturer, to get
their<br>
entire scoop on the project. It may be an overly-cautious approach to
liability<br>
concerns. If starting from scratch, the truss manufacturer should be
able to<br>
design for whatever the application requires. Sistering boards to
their trusses<br>
might easily freak them out as well. Ask them what they would suggest.
There are<br>
lots of truss manufacturers if this one can't handle the job.<br>
<br>
Dick Ratico</blockquote>
<blockquote type="cite" cite>Solarwind Electric<br>
<br>
<br>
--- You wrote:<br>
Hello Wrenches,<br>
<br>
I just talked to a carpenter, who we are installing an array for.
He<br>
is putting a new roof on the building and was talking to the<br>
manufacturer of the trusses. He mentioned that he was having
an<br>
array installed on the roof.<br>
<br>
The truss manufacturer said there were problems with weakening the<br>
truss structure with the lag screw penetrations. We are now
planning<br>
to sister boards next to his trusses instead of penetrating them.<br>
<br>
Does this seem like a potential issue? Is there any data on
this?<br>
<br>
Thanks,<br>
<br>
Drake<br>
<br>
<br>
Drake Chamberlin<br>
Athens Electric<br>
OH License 44810<br>
CO License 3773<br>
NABCEP TM Certified PV Installer<br>
Office - 740-448-7328<br>
Mobile - 740-856-9648
_______________________________________________<br>
List sponsored by Home Power magazine<br>
--- end of quote ---<br>
_______________________________________________<br>
List sponsored by Home Power magazine<br>
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</blockquote>
<blockquote type="cite" cite><br></blockquote>
<blockquote type="cite" cite><br>
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List sponsored by Home Power magazine<br>
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List Address: RE-wrenches@lists.re-wrenches.org<br>
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<div><br></div>
<div><br></div>
<x-sigsep><pre>--
</pre></x-sigsep>
<div>~~~~~~~~~~~~~~~~~~~<br>
Jeff Clearwater</div>
<div>Senior Design Engineer</div>
<div>Village Power Design<br>
Solar Design Consultation for the Commercial Sector<br>
http://www.villagepower.com<br>
gosolar@villagepower.com<br>
<br>
Voice: 831-427-2799<br>
Fax: 413-825-0703<br>
245 Dufour St<br>
Santa Cruz, CA 95060<br>
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~</div>
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