Residential Truss Engineering Logistics
Residential Truss Engineering Logistics
(OP)
Typically when designing residential new construction (north and central Florida)I am given the architectural plans and the truss shop drawings. I design all the shear walls, headers, posts, foundations, etc. etc. I take the loads from the truss shop drawings and take care of any large point loads, design my uplift connectors, gable bracing, and anything else that needs to get taken care of. If nothing pops out at me and everything checks out I approve the shops and submit these with my structural plans. Every now and then I will catch a truss or girder floating out in space or the truss engineer using the wrong wind speed/exposure. I will bring this up and it gets taken care of.
Recently I had a project in South Florida where when I asked who had the truss shop drawings they looked at me like I had 5 heads. They told me that I was to do the truss layout and then they would submit my plans and calcs to the city for plan review/permitting. To me this sounds arse backwards especially with 180mph wind speeds and a complex residential roof layout. They told me the trusses get designed after they get a permit to build. Yes I could put together a preliminary layout and get a general idea of the loads but why would I when I know the truss engineer is the one who produces the final truss layout and design? I told them no, they got all pissy but did get me truss shops and everything went smoothly.
I called around to some colleagues and even some other truss companies I have worked with and received a mix amount of answers. It seems to me that it might be based on the area you are designing in and how the contractors/municipality works. To me doing a preliminary layout and basing your design on it asks for issues down the road and things that might get missed once the final truss engineering is complete. Any feedback on what is typically done in other areas would be much appreciated.
Recently I had a project in South Florida where when I asked who had the truss shop drawings they looked at me like I had 5 heads. They told me that I was to do the truss layout and then they would submit my plans and calcs to the city for plan review/permitting. To me this sounds arse backwards especially with 180mph wind speeds and a complex residential roof layout. They told me the trusses get designed after they get a permit to build. Yes I could put together a preliminary layout and get a general idea of the loads but why would I when I know the truss engineer is the one who produces the final truss layout and design? I told them no, they got all pissy but did get me truss shops and everything went smoothly.
I called around to some colleagues and even some other truss companies I have worked with and received a mix amount of answers. It seems to me that it might be based on the area you are designing in and how the contractors/municipality works. To me doing a preliminary layout and basing your design on it asks for issues down the road and things that might get missed once the final truss engineering is complete. Any feedback on what is typically done in other areas would be much appreciated.






RE: Residential Truss Engineering Logistics
This makes sense to me because YOU are the engineer of record and are responsible for the overall structural layout, framing, system, etc.
The pre-manufactured trusses are a delegated design from you to the truss manufacturer.
Relying on truss designers to initiate shop drawings where I have no control over the wind speed, exposure, direction of framing, etc. just lends itself to problems later when you try to have the truss designer correct something design-wise or revise anything.
I've never had truss shops presented to me prior to my design set going out.
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RE: Residential Truss Engineering Logistics
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Residential Truss Engineering Logistics
I like to debate structural engineering theory -- a lot. If I challenge you on something, know that I'm doing so because I respect your opinion enough to either change it or adopt it.
RE: Residential Truss Engineering Logistics
I've not seen it done that way (I'm in the southeast by the way).....but I haven't done much residential either.
RE: Residential Truss Engineering Logistics
I do give them wind speeds, exposures, and other wind data up front most of the time and I do also get a fair amount of jobs were it's done and they get all the project design criteria right without any guidance. I guess if I was forced into doing it the other way I could see where it would give me more control over the design but I don't need all that control for the residential work I do unless there are problems.
RE: Residential Truss Engineering Logistics
Your process is backward. I practice in Florida as well.
If you are the engineer of record, YOU decide the loadings.....not the architect and not the truss designer.
It's ok for the architect to provide a preliminary truss layout for dimensional continuity; however, you are responsible for all structural decisions.
Read Florida Statute Chapter 471 and Florida Administrative Code (FAC) 61G Rules of The Board for how delegated engineering is to be done. You delegate to them.... not the other way around!
RE: Residential Truss Engineering Logistics
RE: Residential Truss Engineering Logistics
I think KootK hit it on the nail, for most of the simple residential I do the truss guys in my area get it right most of the time which makes for less back and forward and a quicker project timeline.
RE: Residential Truss Engineering Logistics
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RE: Residential Truss Engineering Logistics
Dik
RE: Residential Truss Engineering Logistics
Step 1: Architect/owner/contractor hires you and gives you the plans to do the structural engineering.
Step 2: You do all the engineering and provide structural plans including a truss layout and all your other standard sheets.
Step 3: You then finalize the design and give the owner/architect/contractor all your plans, calculations, invoice, ect.
When do the final shop drawings get reviewed and approved/disapproved by the EOR in this process? Is it after step 3, during, or before? For most of you this might be elementary but I am trying to get some perspective(constructive criticism) from other engineers in different areas. If anything maybe there are some changes I can make with my clients and/or the truss designers to make the process easier or more efficient.
RE: Residential Truss Engineering Logistics
The one residential exception is apartment projects. I often find that the building department will accept the trusses as a deffered submittal on this type of project and that the framer actually contracts directly with the truss co. In this case I do prepare my design and develop a truss layout. I then have to go back and review and approve the truss submittal.
RE: Residential Truss Engineering Logistics
When I researched into why this was so - the truss manufacturer stated that they just ordered trusses per the owner's sketch and provided them - that it wasn't their job to verify loading, etc.
The owner wasn't a design engineer and didn't have a clue about snow loading criteria.
So I'm very suspect about truss manufacturer's providing accurate load/snow/wind/seismic input into their little canned programs and then some guy from a distant land signs and seals them.
I suspect in this collapse case the guy running the truss software wasn't well versed in engineering.
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RE: Residential Truss Engineering Logistics
RE: Residential Truss Engineering Logistics
RE: Residential Truss Engineering Logistics
JAE, that is something I have seen too. Not to the point of collapse but to were the loadings got missed because the contractor/owner was the one who ordered and paid for the trusses. Trusses were installed already and the owner wanted me to just "stamp it" for a permit. I said have a nice day and good luck finding a stamp for this one. People have no clue sometimes; this only happened once but still a huge mess up.
ACE58, you made a good point about when you were an EIT and how the truss guys would change your layouts for a more economical design. Like you said, you started to get better at your layouts over the years but why would I base my final design on my own interpretation or assumptions of how it needs to be laid out? Even if I do base my design on my own assumed layout how do I know a plan reviewer, contractor, inspector or whoever is going to catch a potential discrepancy from my assumptions and the final truss drawings? Obviously coordination and communication are the key but that doesn't always happen in the extremely fast paced residential market.
My process for this whole truss situation is that I will not finalize my drawings/calcs and sign and seal until I have the final truss shop drawings. We are the ones who are ultimately responsible for the structure right Even if its not my fault that something got missed I would be the first one the attorney calls. I would rather be the last one to review the final truss shop drawings instead of a plan reviewer, inspector, contractor, ect.