only need to confirm in a letter (at least this is how it works in the four or
five building departments in my area) that the trusses conform to the intent of
your design for the specific job. In other words, the calcs were designed using
the live and dead loads provided by you, the trusses match the roof layout on
your roof plan and that drag trusses have been provided where you specified on
the plans. Beyond this, you are required to complete the load path after the
placement of the trusses to the foundation.
is a sample of a letter I provided a few years ago - since then I have shortened
them whenever possible:
"I have reviewed the truss
calculation package from <deleted> for the projects located at <address
of job>. The trusses conform to the intentions of the architectural and
structural design as noted on sheet S2.1 of the structural drawings drawing. The
only discrepancy lies with the indicated plate height which is specified on the
truss package as 10’-1” but is actually 8’-1”. This does not change the design
of the trusses nor does it impact the project in any manner.
The T-3 truss is correctly designed for the drag load of
5,200 pounds. This can be verified on the structural analysis
The live load of 16 psf is consistent with a 4:12 pitched
roof and is in compliance with table 16-C of the 1994 Uniform Building Code. The
roof dead loadincluding the
ceiling load is consistent with mission tile roofing. The structural analysis
uses a 20 psf dead load but includes a miscellaneous load. The 19 psf load used
by <truss manufacturer>
is within a reasonable
range for this roof material.
accept this letter as my authorization for acceptance of the truss calculations
submitted by <truss manufacturer>."
This is generally all
that has been required. It does not establish any more responsibility upon the
EOR for the actual design of the roof system which remains with the truss
manufacturer's engineer. It does however, place responsibility on the EOR to
insure that the total system meets the minimum or greater live and dead loads
applied to the rest of the structures and which were used to evaluate the
lateral load resisting system. It also places responsibility on the EOR for the
connection of the roof to the structure below and for all lateral load path
I'm sure there are more
conservative engineers out there that will disclaim much more, but this seems to
be in line with what other engineers in my area are providing. If you do,
however, note a problem with the trusses (I've discovered girder trusses where
the loads were distributed incorrectly based upon the truss designers layout)
you must address it and require correction of the package. In short even though
you may not be responsible for the design of the truss system, you are ethically
responsible to check it thoroughly to find faults that can be problematic and to
bring them to the attention of the truss designer.
Dennis S. Wish,
-----Original Message----- From: SCHFUN(--nospam--at)aol.com
[mailto:SCHFUN(--nospam--at)aol.com] Sent: Saturday, May 26, 2001 7:11
PM To: seaint(--nospam--at)seaint.org Subject: EOR review of truss
is the standard of practice for the design engineer's review and stamping
of pre-fab trusses? Building departments in Southern California
often require this, and some engineers are uncomfortable with the practice
of stamping the work of another engineer (the truss designs are typically
prepared using a proprietary computer progaram and reviewed and stamped by
the truss engineer).
Is the engineer-of-record expected to check
the truss calculations? Or just verify that the proper loading criteria
was used in the truss design?