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RE: Question on wood Roof Trusses

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George,
One issue with your explanation that I happen to agree with. It is not
possible for an engineer to design the connections of a plated truss without
the design information on the specific truss plate used. This information is
protected as proprietary information by the different Plate company's and is
not available to the EOR. If you ask Alpine Truss for their plate data so
you can design the truss in your office with the intention of producing a
job-built truss or to take to other lumber yards to manufacture, you will
not get it. They work with specific software developers like Keymark
Industries who create the truss program and then license it to lumber yards
who produce trusses using the proprietary press plates.
Truss fabrication is a highly competitive industry - especially here in the
desert. When I left Los Angeles eight years ago, I had a custom home which I
wanted to design with trusses. I was only able to find one company in
Ventura county at the time who would provide the trusses, including the
design. When I arrived in the desert, I felt like an apprentice again when I
discovered that virtually every home was constructed with trusses. In fact,
in the last eight years, I am working on my first home that was constructed
using stacked lumber and I simply can not see how the designer justified the
cost. I have, admittedly, gained a tremendous respect for plated trusses.
There is no question that engineers or inspectors (especially on
conventionally framed homes) need to have a keen eye to identify the
defects, but to protect the trusses from unauthorized and dangerous
modifications by contractors in the field.
I remember a number of homes where the contractor nailed braces for soffits
to the bottom chord of the truss at plate locations effectively splitting
the lower chord. I've seen trusses stored on top of homes laid upright at an
angle supported to stud walls with 2x4 braces until the trusses could be
distributed and set permanently in place (a technique that will warp and
possibly damage the trusses). I've seen struts cut to allow for mechanical
ducts to pass and the inspectors had not caught the problem. There are a
number of possible field abuses.
Most of my point is that the truss is proprietary and it is next to
impossible for an engineer to design a plated trusses without the
proprietary information that the manufacturer protects. Until this changes,
there is little we can do other than act as the EOR of the project and
distance ourselves as much as possible from possible problems with the
system that we can not anticipate without the proprietary information.

I don't add for truss review to my contract, but then again, I don't reduce
my fee because a client wishes to use trusses over having me design the
roof. I figure, that the time I save in the design I pick up in the
coordination and responsibility as the EOR. So far no client has complained
about this.

Dennis S. Wish, PE

-----Original Message-----
From: George Richards, P.E. [mailto:george(--nospam--at)BORM.com]
Sent: Saturday, January 13, 2001 10:23 AM
To: 'seaint(--nospam--at)seaint.org'
Subject: RE: Question on wood Roof Trusses


We do not view the truss designs that we review as inherently incomplete.
The designs we review generally conform to TPI standards and to our
drawings.  As EOR we are responsible for the performance of the structure.
As EOR we could design the trusses ourselves and provide construction
documents showing how the trusses are to be built.  However, industry
practice is to allow the trusses to be design-built with the design by a
Specialty Engineer.  So then what defines exactly what the specialty
engineer will do and what will we do?  First, there is a TPI document
defining our respective responsibilities.  Second there are the project
specifications (on our drawings) which further define our responsibilities.
The Specialty engineers designs the trusses themselves and truss to truss
connections.  We design the braces.  The proprietary of the product is the
trusses themselves.  They got stuck with the hangers because they are in the
best position to design the hangers.  The rest is ours unless we
specifically define otherwise in the construction documents.  I am not
saying this is the best way, right way, or moral way.  This is in general
what the industry practice is and this is how we do our work.  The client is
not paying extra.  He is not paying us to design the trusses. He is paying
for a responsible person to assure that his structure is being built
correctly and to keep the design-build vender, who gets the job based on
lowest price, honest.

BTW our fee always includes as part of the base price one truss review.  We
have assigned part of the design to the structure to another engineer.  How
do we know that he likely followed our design intent unless we look at his
work?

Respectfully, George Richards, P. E.



-----Original Message-----
From: Roger Turk [mailto:73527.1356(--nospam--at)compuserve.com]
Sent: Saturday, January 13, 2001 9:39 AM
To: seaint(--nospam--at)seaint.org
Subject: RE: Question on wood Roof Trusses


George Richards wrote:

>>I second Mr. Moore's opinion.  Our plans (for houses, not even commercial)
require that we review the roof truss drawings for conformance with our
design intent.  Over 90% of our builders do send us the drawings for review
prior to fabrication. The truss drawings are then forwarded to the Building
Official so that he can approve them.  This is in accordance with the UBC
section on deferred submittals. The Clients know up front that this is the
process and they pay for the service.  What the get is a safer home more
likely to be free of defects in design and construction.<<

Why should the client pay for an incomplete design of a proprietary product
and then pay the EOR extra to complete the design?

A. Roger Turk, P.E.(Structural)
Tucson, Arizona