Wood Truss Load Responsibility 3

[JAE]

I'm providing some engineering consulting services on a structural failure of an agricultural building where the roof collapsed under snow loading. The roof was comprised of wood trusses spaced at 4'-0" o.c. and spanning about 75 feet. I analyzed the trusses, using the truss manufacturer's spec sheets for capacities, and found pretty quickly that they failed due to an unbalanced snow loading on the leeward side of the roof. That's not really the issue.

Most wood trusses are called out by the designer of a project. This is usually an engineer. But in this case, there was no engineer. The "farmer" was coordinating the activities of the work, called up a local lumber yard and ordered the trusses. The lumber yard conveyed the order to a truss manufacturer who simply plugged in 20 psf for the roof snow load and sent the underdesigned trusses on their way.

The Truss Plate Institutue Specs and all other info I can gather dictates that the designer is responsible for calling out or determining the proper live loads. But in this case, the farmer didn't have the background/know-how to do so. He had no idea what a snow load even was. The truss designer knew that these trusses were headed to a ground snow load area of 45 psf.

Wouldn't it be the Truss designer's responsibility to at least question his own decision to use 20 psf?

 

[Ron]

Interesting timing. I just received this bulletin from the City of Jacksonville, Florida Building Department

Note that there seems to be a provision for the truss designer to be considered the Engineer of Record for the limited portion of the truss work, in the absence of a Project Structural Engineer of Record....

May 23, 2001


MEMORANDUM

BULLETIN G13-01

To: All Interested Parties

From: Thomas H. Goldsbury, P.E., C.B.O.
Chief, Building Inspection Division

Subject: Change to Rules Governing Truss Design Package

A recent change to Florida Board of Professional Engineers, Rules Chapter 61G15, Florida Administrative Code, regarding the design of structures utilizing prefabricated wood components, now permits, in the case of a truss design package, a cover or index sheet may be signed and sealed in lieu of signing and sealing each individual sheet, provided that the cover or index sheet contains the following information:

1. The name, address and license number of the Engineer of Record for the truss design package.
2. Identification of the project, name of the authority having jurisdiction (city/county), the loads, and the name date of the applicable building code that the truss design is intended to meet and all loads imposed on the structure.
3. Truss engineering design criteria with full identification of the source of the criteria. The source will be either the Engineer of Record (if there is an Engineer of Record for the structural engineering documents), or the engineer employed by the truss manufacturer. If there is an Engineer of Record for the structural engineering documents, that engineer shall be identified with his/her name, license number and address, along with a check mark to ensure that the drawings have been reviewed as required by Rule 61G15-30.006(3), F.A.C.
4. A truss layout plan by the Engineer of Record showing the location and designation of each component.
5. Identification of the computer program used for engineering the trusses.
6. An index of the attached drawings. The naming and numbering system utilized for the drawings shall be clear as to how many drawings there are in the set and the date of each of these drawings.
7. Each of these drawings in the package shall bear a title block bearing the printed name, address and license number of the Engineer of Record for the truss design and the date of the drawings.

If the above conditions are not met, then all sheets of the truss design package shall be signed, sealed and dated by the Engineer of Record for the truss design package.

Seals for either option shall be metal-type impression seals as per
61G15-23.001 F.A.C. (no wet or rubber stamp type seals permitted).

 

[infoguy]

Ron:

You have read too much into this letter. It does not deligate the responsibilities of the building designer to the truss designer. It simply says that the truss designer is not required to sign every page of the truss submittal package.

I suggest that everyone checking truss designs should read the commentary to WTCA 1-1995 (Similar to TPI 1-1995). Look on the web site

http://www.Woodtruss.com

under legislative issues.

We must always remember that the model building codes give the ultimate responsibility for conforming to the building code to the "permittee". This is defined as the building owner. They may hire professionals to perform this task, but if they choose not to hire professionals to do this, they take all risk into their own hands. I think you will find that all engineers who work in the truss industry would like professional engineers and/or architects to review all truss designs prior to fabrication.

 

[Ron]

InfoGuy...The noted letter, when read in conjunction with Rule 61G15 of the Florida Statutes makes it clear that the engineer designing trusses (or other structural components) has a significant responsibility, including signing and sealing documents. The letter only points out a particular instance in which signing/sealing may be limited to a cover sheet.

While I agree that a permittee has the responsibility for code compliance in the construction, that does not mean that a construction permittee has the responsibility for design under separate law. If that premise were valid, then every contractor would have the responsibility to see that the Architects and Engineers of a project complied with the code in their designs. That is not the case. It is the engineer, whether or not there is an "official" engineer of record, who has a duty to meet the local standard of care in his practice. It is the engineer who is licensed, not the owner, nor the contractor.

 

[RDK]

I just came across this thread.

Any resolution or court ruling? Rick Kitson MBA P.Eng

Construction Project Management
From conception to completion

http://www.kitsonengineering.com

 

[JAE]

Not yet. It is amazing how long these cases last. The trial is set for next year, maybe in May.

 

[youngstructural]

ANy resolution yet? Very curious to see how this turned out...

Thanks,

Y.S.

 

[jike]

JAE:

Before Wisconsin adopted the IBC 2000, I believe there was an exemption for agricultural buildings to be designed for 20 psf roof load. I do not know what the current regulation is.

I do not know what State your building is in, but Wisconsin is certainly considered a northern State.

 

[JAE]

To be honest - I don't know of any resolution - in many cases, the lawyer hires me to investigate, report, comment, etc. and then the case gets into the negotiation phase where a settlement is reached and this is usually confidential.