Metal Plate Connected Wood Truss Submittals

[OHIOMatt]

In the last several years, the quality of information contained in wood truss submittals has deteriorated to a frustratingly terrible level of quality. We routinely see that the incorrect wind and snow loads are applied. We see the incorrect building code, incorrect enclosure classifications and so on. I and a couple of colleagues have been digging into this, and this is what we have found as the typical process.

The general contractor sends the construction drawings to the local lumber yard.

A technician at the lumber yard inputs the data into the truss design software

The output is sent to the truss engineer who adds a cover page that states the design is based upon the lumber yard's interpretation and seals.

The actual truss engineer never reviews the contract documents to verify that the truss design conforms. How is this acceptable by any engineer code of ethics?

 

[phamENG]

Acceptable is a stretch...more like a gray area?

The engineer probably has wording in his/her contract that they only have to verify the design based on criteria provided by the truss manufacturer. So, contractually, they aren't checking trusses for building A, they are checking a truss of dimensions X, Y, and Z for loadings 1, 2, and 3. The manufacturer then sells that component to a builder to install in building A. So it's sort of like engineering for a garage door; or perhaps a semi-custom garage door. I design a door and its attachments for a certain wind load, and then the manufacturer markets it to places with that wind load. If they sell it in the wrong place, is it my fault?

I agree that the truss engineer should pay more attention. Maybe require the cover sheet of their calcs to include a statement:

"I <Truss Engineer, PE>, have reviewed the design requirements, loads, and dimensions shown in the contract documents for the structure in which these trusses will be used located at ABC Main Street. The following calculations demonstrate that the trusses to be manufactured by TrussBuilder, Inc. meet these design requirements, can safely support the required loads, and satisfy the stated serviceability requirements. Signed, etc. etc."

And keep rejecting it until they provide it.

 

[OHIOMatt]

Thanks phamENG. We do require that in our specs and general notes, and they just refuse to provide it. We based our requirements on the TPI-1 document, which is adopted into the IBC by reference. It is very frustrating and in my opinion borders on plan stamping.

 

[Brad805]

Ron the Redneck had a long discussion on truss aspects. Old thread This might be of interest since it adds some context from the supplier side.

I agree the design process is broken. The residential supply world is so focused on minimum cost they don't pay. I believe most truss engineers are paid per truss and it is not great. We have a project right now where the first submittal they totally changed our floor diaphragm design, rejected, second submission, missed partition loads... I hate wood trusses. Luckily with the increase in wood prices I have been able to persuade some to use different products.

I doubt you will ever get any truss engineer to issue a drawing with Pham's note on a sealed drawing. They do not do that, and it seems to be the norm in this industry. If they did, they could seal the layout drawing.

 

[Aesur]

This is one example of why jurisdictions in my state are starting to push that the EOR has to review the complete truss package and shop stamp the layout as well. Previously this was the contractors job to coordinate as far as I understand it, but they are coordinating less and less these days. This is why CA fees will start increasing significantly if this goes through.

As Brad805 said, RontheRedneck provided a lot of great insight into the industry, I believe he (or someone else) even touched base on how little truss engineers are paid to stamp that the design is correct using the inputs in the software only.

 

[WinelandV]

We can rag on the truss provider and their engineer, but doesn't the GC bear some responsibility here?

"I need trusses for this project. Here are the structural drawings - please note the required loading and geometries. I won't even send this on to the EOR if it's not right, and I'm not going to pay you more to get it right even if it takes you 10 tries."

Please note that is a "v" (as in Violin) not a "y".

 

[phamENG]

winelandv - in a broader sense, yes, but I think OHIOMatt's major concern is the ethical practice of engineer here.

Maybe I'm just a sucker, but when I get a call from a contractor or fabricator to do delegated design work, my first step is to say thank you for sending me what you think I need to design this, now please send me the entire drawing set and spec book. I have never not found something in a sheet that the GC didn't give me that influenced my delegated design. In most cases the GC is trying to help so I don't have to sift through a bunch of stuff that doesn't matter. But I do it because I feel that I'm ethically obligated to ensure my piece fits...it's the EOR's job to come back and make sure I did it right.