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RE: Question on wood Roof Trusses

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Stan, you can get the icbo reports on the plate data but there is specific
plate capacity information and physical properties that are not indicated in
the ICBO report that are used for plate stress calculations which are
protected by the plate manufacturer.

Plate manufactures don't necessarily design their software as one other
person suggested. Keymark industries is the manufacturer of Truss software
for many plate manufacturers, including Alpine. The specifications,
tolerances and capacities (stress and load ratings) are protected by the
plate manufacturer. The truss software is licensed by the plate
manufacturer, but the software is often produced by one company - Keymark,
although there are a couple of different software's available to truss
companies.

Dennis

-----Original Message-----
From: sscholl2(--nospam--at)juno.com [mailto:sscholl2(--nospam--at)juno.com]
Sent: Saturday, January 13, 2001 2:29 PM
To: seaint(--nospam--at)seaint.org
Subject: Re: Question on wood Roof Trusses


I have had to furnish plate data for trusses and did not have trouble
getting
the data which was an ICBO ER report.

Stan Scholl, P.E.

On Sat, 13 Jan 2001 12:14:17 -0800 "Structuralist" <dennis.wish(--nospam--at)gte.net>
writes:
> 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
>
>
>
>