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Re: Bracing for Nail-Plate Wood Trusses

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Chris Banbury, Pat Clark, et al:

Interestingly enough, the "Metal Plate Connected Wood Truss Handbook," 2nd
Edition, Wood Truss Council of America, 1997, does *not* consistently place
the responsibility in the same way that the TPI does.  Some quotes from
Chapter 15 of the Handbook, 2nd edition,

"Section 15.4 Contractor Recommendations:
"2. Prior to erection and installation, determine necessary truss bracing,
locations of bracing, and methods of installation.  The services of a
structural engineer may be required.  ...
"4. Have a structural engineer review installation and erection procedures
using DSB-89."

Elsewhere, they toe the same line as the TPI, except that they do several
places say that the bracing should be "... installed and fastened per the
building designer's specifications."  Implying, I guess, that we can specify
the performance of the bracing, and hand it back to the fabricator.

Also, document HIB-91 that is often referred to includes phrases such as
"Permanent continuous lateral bracing as specified by the truss
engineering," in a note pointing to a diagram of web bracing.  Again, not
consistent.

So, it seems we all agree that for reasons of construction sequencing, total
roof system economics, and a reasonable placement of responsibility and
liability, it makes no sense whatsoever for the EOR to come back into the
project after shop drawings are done and design the bracing.  We all know
*how* to do it, if need be, but it is really neither standard practice or
sensible practice.

Now, does anyone know or have any ideas how we go about changing the
situation?  Get all of our SEA's to set policies and write letters to ANSI,
TPI, WTCA, ICBO, ICC, Florida State Board, and so on?

We also should insist that the building departments enforce the same rules
for all buildings with truss roofs, including the "building designer"
projects that we never see, and not just the ones that are designed by
engineers.  About the tenth time that the contractor has to go out to hire
an engineer just to design the bracing, he/she will start leaning on the
truss fabricators for a change.

-- 
Kris P. Hamilton, P.E.
Geiger Engineers
114 West Magnolia Street
Suite 505
Bellingham, WA  98225
Ph: 360 734 7194
Fx: 360 734 7399


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