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Re: Plated Wood Truss Responsibilities

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I received some private replies, but had missed my Thursday night digest of the SEAINT list to see the original response(s) to my message. It should be pointed out that there were two types of bracing designed or specified by the Truss Designer. The first was lateral bracing within the diagonal struts that were used to brace the struts in axial compression and to help prevent out-of-plane buckeling of the trusses. The second type of bracing was specified for all flat top chord trusses where sheathing was not applied directly to the trusses. In this second case, a high conventional roof based on a prescriptive lumber sheet added to the truss package intended to joint a number of short ridges due to the irregular shape of the structure below and the fact that valley’s and hip’s did not converge. With the slope of the roof, the 2x high rafters were supported by Jack Studs that were attached to the nodes at the top chord of the trusses. However since the upper chord was not sheathed, the truss drawing called for 1x3 braces to be placed at 12-inches on center over the top chord of the trusses and these were omitted.

In no case was the requirement I mentioned not indicated on the design drawings. They were simply missed at the time the roof system was constructed and this led to excessive deflection of the conventional (prescriptive) roof rafters that the owner spotted first from the exterior of the home.

The issue is one of responsibility to the public above and beyond the company that employes the engineer to design and wet seal the truss calculations. Since I was not involved in the original design of the home and the EOR who was is not available or willing to be involved in the remedial work, I felt that this was the reason I was hired – to identify the deficiencies and help find an equitable solution to the problem. However, if the truss company will not allow their engineer or if the engineer acting as the truss designer refuses to compare the remedial work done with the actual work performed in the field, then the project can not be finaled and it will ultimately end up as a public nuicense with respect to the city. This opens even more worms for the owner who will be fined and threatened with a misdemeanor in the city for not completing the work that was started. Personally, I won’t subject myself to the potential liability now or in the future to make the judgement call for the truss company who I believe is responsible and capable of making site comparisons to their design drawings and then either requiring corrections or sending a letter to the building official under the terms of Structural Observation that the work done conforms with the intent of their design drawings.

 

I hope this is clear.

 

Dennis S. Wish, PE

California Professional Engineer

C-41250 Exp. March 31, 2007

Structural Engineering Consultant.

 

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From: "Gary Hodgson & Associates" <ghodgson(--nospam--at)bellnet.ca>

To: <seaint(--nospam--at)seaint.org>

Subject: Re: Plated Wood Truss Responsibilities

 

On 25 May 2006 at 13:54, Jordan Truesdell, PE wrote:

 

I would take issue with that.  Up here, I know of no law forbidding the truss manufacturer from designing bracing.

Sounds like something cooked up by the TPI to cover their collective butts.

Gary

 

>

> The truss fabricator, a very large organization, flatly refused to do

> the work. Not just refused, but claimed that according to TPI it was

> legally forbidden for them to do so.  As a result, I will be charging

> more than my original consulting fee to design the bracing now.

>

> Jordan