[RE-wrenches] Tile Roof mount compliance

[William Miller]

Nick:

 

We have structural engineers we work with on a regular basis, but we have never had to engage one in this particular capacity.  On this particular job there are two things unique:

 

1.    We are being asked to document the truss construction but not being asked to have any structural analysis performed on the truss.  I don’t believe a building official will be performing the calculations, so why bother?  (We have argued that the PV equipment is allowed to use the capacity reserved for “live loads,” obviating the need for engineering.  This is generally described as three pounds per square foot.)

 

2.    We have never been required to get an engineer’s stamped approval to attach lags to a truss member.  I am fully aware that it is quite possible to do this job incorrectly.  The lag must be sized so as not to split the wood and it must be applied near the middle of the truss member.  Again, no structural analysis is being required, so up-lift is not an issue, therefore lag size is not an issue.  I think it a bad precedent that solar contractors be required to hire an engineer every time they drive a screw.  California passed and adopted AB2188 that promotes streamlined permitting.  In the draft guide book are guidelines for proper lag application, specifying where on the width of a truss member a lag could be driven.  I think it much more sensible if a building jurisdiction require that a protocol be established for proper workmanship rather than require the added expense of having an engineer approve every fastener.  The jurisdiction is absolutely correct in their citation and application of the building code – it does say an engineer must approve any modification, including drilling -but this added expense for engineering does not seem sensible.

 

I am looking for any help from the members of this list-serve for strategies for negotiating with the building officials reviewing this permit application.  I have presented documentation from the proposed AB2188 guide book.  The legislation does not apply until September of 2015, but we have used the same strategy when citing pending code changes to some success.  Any other ideas are welcomed.

 

Sincerely,

 

William Miller

 

 

Gradient Cap_mini
Lic 773985
millersolar.com <http://www.millersolar.com/> 
805-438-5600

 

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Nick Vida
Sent: Friday, November 21, 2014 8:52 PM
To: wrenches
Subject: [RE-wrenches] Tile Roof mount compliance

 

Hi William,

 

We deal with this all day in California. You should go in the attic, figure out the truss type (howe, scissor...), get the spans and sizes of the wood, and pictures of the grade stamps. You can then send this off to a structural engineer to get a letter and a digitally stamped set of your plan set. The Engineer may request structural additions, or different spacing for the penetrations, but most truss is pretty sturdy and capable of supporting the solar panels. 

 

If you throw a rock on linkedin, you will hit a Structural Engineer. If you need some help, send me a note off list.

 

Nick Vida

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