A truss designer on the project I a
A truss designer on the project I a
(OP)
A truss designer on the project I am overseeing is trying to convince me to not make them consider the weight of partitions in their truss design based on the following excerpt from TPI publication. Has anyone run into this issue before?
ANSI/TPI 2002, Section 2.2.5, “The weight of non-bearing partitions shall be permitted to be ignored for truss design purposes given the following conditions; if the following conditions do not exist, the Building Designer shall specify in the structural design documents the non-bearing partition loads that need to be applied to the trusses:
(a) Trusses are not spaced over 24 inches on center;
(b) Top chord panel length of supporting trusses does not exceed 30 inches;
(c) Design live load of supporting trusses results from a residential occupancy and is not less than 40 psf;
(d) Partition weight does not exceed 60 pounds per lineal foot; and
(e) When partitions parallel to supporting trusses are not located on or immediately adjacent to a truss, the sub-floor shall be of adequate strength and stiffness to support the partition load, or other provision shall be made to distribute the partition weight to the supporting trusses.
The truss layout for the project satisfies all the conditions above, and the designer wants to ignore the partitions loads in their truss designs. But, I am not sure if this is in compliance with the building code. Your feedback is greatly appreciated.
Thanks.
ANSI/TPI 2002, Section 2.2.5, “The weight of non-bearing partitions shall be permitted to be ignored for truss design purposes given the following conditions; if the following conditions do not exist, the Building Designer shall specify in the structural design documents the non-bearing partition loads that need to be applied to the trusses:
(a) Trusses are not spaced over 24 inches on center;
(b) Top chord panel length of supporting trusses does not exceed 30 inches;
(c) Design live load of supporting trusses results from a residential occupancy and is not less than 40 psf;
(d) Partition weight does not exceed 60 pounds per lineal foot; and
(e) When partitions parallel to supporting trusses are not located on or immediately adjacent to a truss, the sub-floor shall be of adequate strength and stiffness to support the partition load, or other provision shall be made to distribute the partition weight to the supporting trusses.
The truss layout for the project satisfies all the conditions above, and the designer wants to ignore the partitions loads in their truss designs. But, I am not sure if this is in compliance with the building code. Your feedback is greatly appreciated.
Thanks.






RE: A truss designer on the project I a
TPI 1-2007 is a referenced standard in IBC/CBC. I'm not sure if its the same or similar to what reference you have been provided, but in either case I would key on the phrase "...shall be permitted...". If your documents specify a partition load be considered then I'd say there is no question, it is to be included, full stop. But if you have nothing noted then you're probably in a bit of a tight spot. You can say do it but how hard do you want to fight for it? The implicit thing in the conditions is that given conformance with the limitations the resulting design should be satisfactory.
regards,
Michel
RE: A truss designer on the project I a
RE: A truss designer on the project I a
Since you have clear instructions to include the load I believe stepping back should be accompanied with some advantage to the Client. What you've provided them is future flexibility in their floor plan by not fixing limits on the interior partitions. If they want to give that up then there should be something offered in trade like cash, schedule...or maybe just future goodwill?
regards,
Michel
RE: A truss designer on the project I a
RE: A truss designer on the project I a
nutte, The building falls under IBC 2009.
RE: A truss designer on the project I a
The plate-connected truss industry has historically placed designers in a bad position. TPI has been trying to delineate responsibilities so that the contractors, designers, and manufacturers each know what is expected. One of the serious problems in the industry was the lack of this delineation, which resulted in improper design loads and construction defects. Because of this, you should be clear that the design should, at your discretion and your selection, either use actual partition locations and loads, or the 15 psf increased uniform load. Be sure the sealed drawings from the manufacturer (usually the plate manufacturer or a contract engineer) specify the correct loading and brace points. Also, have a way to verify the quality of manufacture to assure the use of the proper plates, grade of wood, and similar items (just as you would for bolted connection.) Once erected, verify the integrity of the trusses and bracing. Properly designed, manufactured, and installed plate-connected trusses are an economical construction method, but they are vulnerable to bad design, manufacturing defects, and construction damage.
RE: A truss designer on the project I a
The big question is what is the job phase?
If it is in first bidding that they are trying to give the client a lower bid on the job. Saving the client a little money. But all the bidders should be given the same chance.
If the job is starting then it comes down to the fact that the Truss Company, most likely, missed bid the job. Much less likely, the Truss Company and/or contractor (most likely the framer) is trying to increase their profits a little.
The cost savings is so small that unless you are building a hundred homes (which is why tracts do not use partition loading) it is not worth it for individual owners. Also, the savings being so small, helping out the Truss Company will only encourage them to do it again. While increasing your liability as you are down sizing the quality of the house.
Personally, I have never seen the partition load being used in a custom residential building. But that is the owner/architect/engineer's decision.
Garth Dreger PE - AZ Phoenix area
As EOR's we should take the responsibility to design our structures to support the components we allow in our design per that industry standards.
RE: A truss designer on the project I a
The project is a 3-story multifamily residential building.
RE: A truss designer on the project I a
RE: A truss designer on the project I a
For partition walls on the project we asked for Simpson STC clips to avoid any loads being transmitted to these walls due to the deflection of the floor above.
RE: A truss designer on the project I a
I'm on record with my reasoning and recommendation and I acknowledge that it creates a fussy detail for the drywall and fire rating. But, whew!
RE: A truss designer on the project I a
The contractor didn't have any issues providing the STC clips specified. I guess they have become a norm in the area I am at.
RE: A truss designer on the project I a
PARTITION LOADING ALLOWANCE HAS BEEN EXCLUDED. PARTITIONS SHOWN ARE FIXED LOCATIONS AND ALLOWANCE IS INCLUDED IN THE DESIGN. ALTERNATE PARTITION LOCATIONS TO BE REVIEWED BY [CONSULTANT | ENGINEER]
The NBC of Canada has loading provision for partitions that are not fixed. And by stipulating that they are fixed, the general partition loading is not required. Sometimes for office buildings, I'll roll it into the live load to give a slight added flexibility.
Dik
RE: A truss designer on the project I a
RE: A truss designer on the project I a