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Re: Plated Wood Truss Responsibilities

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Dennis:
 
All of the residential truss calcs I have been familiar with refer to the TPI for permanent and temporary bracing but the contractor installing the trusses has to be aware of what members need bracing, type and location.  The truss engineer is the only person qualified to determine this as he has generated member size and connection requirements on  some type of truss software and he should be willing to do this if some one will pay him for his time. It will be a chore for someone else to do this, not knowing the lumber grade and type metal plates used in the fabrication.
 
However, if the original truss engineer will not inspect and prepare aproper fix, and it is a simple lack of bracing and the locations are known, or a top chord deflection, the repair strengthening  recommendations could be based on the design for dead and live loads on the chord member and an assumption of lowest grade of DF lumber, knowing it's size and continuity. Otherwise a truss repair company's engineer will have to analyze the existing truss profiles and members in the problem areas and stiffen or brace members or strengthen connections as dictated by the calcs.
 
Hope this helps.
Ray Shreenan
 
----- Original Message -----
Sent: Thursday, May 25, 2006 9:03 AM
Subject: Plated Wood Truss Responsibilities

I need some advice. I was hired nearly six months ago to identify the problem associated with a custom home roof system. The roof is constructed of wood trusses (press plate manufactured) that were designed by a company whose name includes ?Roof Truss Systems.? This point becomes evident in my question later.

The home was constructed six to eight years ago by a local developer / General Contractor. I was not the engineer of record and was retained because the owner identified what he believed to be a defect in the roof and needed to disclose or repair the problem so that he could sell the home. The price of the home is approximately $1M dollars.

I performed an inspection of the area that I was able to access in the roof and wrote up my report with recommendations. The assembly of the truss system was defective in at least three areas where requirements in the truss analysis and design package were omitted. Lateral bracing was missing from the locations noted on the truss sections and the top chord of flat roof trusses that were not sheathed were missing the required 1x3 bracing at 12-inches on center. There were other minor defects but these were the most prevalent.

The owner originally noted a roof deflection from the outside of the home and reported this first to the developer. The developer hired a sub-contractor to make repairs but did so without obtaining building permits. In addition, the corrections that were done were not, in my opinion, adequate even though they did correct the visual defect.

The owner?s intent was to correct the problem so as to have nothing left to disclose.

 

A meeting was held between the owner?s agent (real estate agent), the attorney for the real estate company, a representative of the truss company and myself. A copy of my report and photographs were distributed to each party so that my specific concerns could be addressed. The developer was purposely left out of this meeting as he was more of an on-going problem than a solution. The Truss Manufacturer also provided a recommendation for a general contractor that they believed could do the repair work appropriately.

 

The terms of my report was to provide a repair plan (a revised truss package was submitted) and a copy of my report was added to the package so that a permit for the work could be issued. I required that a structural observation be done by the truss designer (the engineer who sealed the truss calculations and analysis) upon completion of the work since it was my belief that only the truss designer could determine if the work complied with the intent of his design.

 

The work has been done and the Truss Company has taken the position that they are not responsible nor qualified to do the Observation since they sold a product that met quality control at the time the trusses were shipped. It was not their responsibility to assure that the trusses were assembled in compliance with their construction documents.

 

I believe that they sold a truss system and that while they are not responsible for the method and means of construction, the engineer who wet sealed the analysis and design drawings is the most qualified to determine if the corrections were constructed as he originally intended. I went to the TPI and WTCA document of responsibility for Wood Trusses and I still believe that I am correct in expecting the Truss Designer to do the observation of his truss system and that this is the only way to insure that the defects have been corrected so as to eliminate the need to disclose an existing defect. The Truss Company Owner believes his responsibility ends with the shipment of the product and the issuance of his design drawings. Since I was not the original Engineer or Record and he is no longer accessible, whose responsibility is it to write up the Observation so that the permit can be finaled?

 

Your opinions on this matter are greatly appreciated.

 

Dennis S. Wish, PE

California Professional Engineer

C-41250 Exp. March 31, 2007

Structural Engineering Consultant.