You may have missed my follow-up to what you quoted below. I think that I
acknowledged that I misread you originally and followed up with addressing
the issue of responsibility for the design of the braces.
I admit that I do not pay as close attention to this issue as it is not
apparent on the truss packages that I receive. I do check for those items
such as inclusion of drag trusses at the locations I design, the type of
bearing of the truss (top or bottom chord bearing), support of girder
trusses in stud walls, top chord slope and transfer of shear through the
diaphragm to the walls.
My second post agreed with you on the issue of compression bracing but
places the responsibility to clearly identify the location of the bracing on
the truss package. The responsibility of the brace design and connection is
the Building Designers. If the Truss manufacturer fails to identify the
requirement for bracing, the Building Designer can not be held responsible.
From: Neil Moore [mailto:nmoore(--nospam--at)innercite.com]
Sent: Friday, January 12, 2001 2:12 PM
Subject: RE: Question on wood Roof Trusses
You missed the point of the whole discussion. The point is that some of
the compression web's of these members have to be braced. They are usually
braced back to the structure. The loads have to be accomodated by the
supporting structure. The truss company has provided you with the values
(although you have to hunt for them carefully in some of the truss
company's output). Everyone complains that this is a fairly messy
If your local building department is only having you review the truss
company's analysis, then they are not enforcing the code. I'm not
defending this situation; I'm trying to only to alert our community to a
long term problem, especially submittals. Our local building department
requires that the bracing is completed before a permit is issued. Review
the 97 code section I mentioned and if you have the TPI code, that also.
What you want to do and what you have to do are two different things.
We're not talking about future codes - the problem is current - and with
the litigation problems in this State, this is something to be aware of.
Of course, I've always wondered how contractor's get their permits with
projects that include prefabricated trusses that they've ordered over the
phone and no engineer of any kind is involved.
Neil Moore, S.E.
>I have not read all of the posts, however I did read Neil's last comment
>this one from you.
>I agree with you on this. The plated truss roof system is isolated as a
>separate system in my area. The EOR is only responsible for the lateral
>connection of the truss system to the structure and any gravity support of
>the girder trusses. A letter is required from the EOR that indicates he or
>she has reviewed the calculations ONLY TO VERIFY THAT THE CALCULATED LOADS
>ARE WITHIN COMPLIANCE OF THE ACTUAL LOADS USED IN THE STRUCTURAL DESIGN.
>If I recall correctly, the latest code or upcoming changes in the next code
>require the truss company to provide more information including the
>connection of truss to truss or truss to girder truss or truss to hip etc.
>There is, in my opinion, a practical reason for this. The EOR does not have
>the resources to design the truss connections or even to verify if the
>calculations are adequate since the truss analysis is based on proprietary
>values protected by the plate manufacturer.
>The second issue, in my opinion, would purposely keep the EOR from assuming
>any responsibility in the design of the roof system as to place the sole
>responsibility for the structural integrity of the roof system upon the
>plate manufacturer and the truss fabricator.
>While I agree that the information Neil brought up should be considered in
>the design of the roof, I am inclined to believe that this is the
>responsibility of the truss manufacturer as all information on the loads
>applied to the roof are provided by the EOR or Architect of record. To
>become involved in a design that you have no control over is taking
>The EOR, as I stated, IS responsible for the connections at points of
>bearing of the roof system to the structure and the appropriate transfer of
>shear to the foundation.
>You May wish to consult the WTCA (Wood Truss Council of America) on this
>issue - (http://www.woodtruss.com).