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Homeowner Forum / Construction / November 2005Joists ... open web or TJI
Basement was poured yesterday and I need to order my floor package early next week. I see people in the neighbourhood are using open web trusses. My supplier has engineered a floor for me using TJI joists. I would like opinions on what peeps here would use? I called my heating guy today and he says he has no preference either way. TIA Gary >Basement was poured yesterday and I need to order my floor package early >next week. I see people in the neighbourhood are using open web trusses. >My supplier has engineered a floor for me using TJI joists. I would like >opinions on what peeps here would use? I called my heating guy today and he >says he has no preference either way. I have a slight preference for using open web trusses in the main floor because it is easier to run the air ducts/piping/wiring across the open spaces. True you can do the same with TJIs but you also have to cut into the joists to create the holes, ergo more work. Are trusses more noisy or prone to creaks than TJIs, that I don't know. 2nd floor - I'd use the TJIs. You might find a slight difference in the installed cost depending on your area, TJI's are trucked into my area from a goodly distance so trusses are slightly cheaper. > Basement was poured yesterday and I need to order my floor package early > next week. I see people in the neighbourhood are using open web trusses. > My supplier has engineered a floor for me using TJI joists. I would like > opinions on what peeps here would use? I called my heating guy today and he > says he has no preference either way. I like using open web trusses. With open web trusses you do not have to worry about cutting too-big/too-many/wrong-location holes in the web of a TJI. > Basement was poured yesterday and I need to order my floor package early > next week. I see people in the neighbourhood are using open web trusses. [quoted text clipped - 4 lines] > TIA > Gary I'd second the preference for trusses over TJI's. The mechanical, electrical and plumbing trades are not as likely to hack your floor apart. If you have enough depth, and you talk to your mechanical contractor, you could design a central duct chase for him and not have to drop any (or minimal) soffits. Trusses...the better way to go. > Basement was poured yesterday and I need to order my floor package early > next week. I see people in the neighbourhood are using open web trusses. [quoted text clipped - 4 lines] > TIA > Gary Although the trusses will allow the subs to run their ducts, pipes, and electrical more easily, I will tell you my experience. I did a lot of insurance work for the past 20 years. I have repaired numerous problems caused by failing trusses. They tend to sag over time and we have had to go into perhaps 100 separate situations where the sagging or failing trusses have caused problems ranging from unsightly to downright catastrophic. You can take your pick, but I would not have them in my house, unless I glued and screwed plywood to at least one side of them (which is what we usually do to repair sagging trusses). The complete failures have to have more done to them. If you glue and screw plywood to one side, then you have a TJI. I can say that I have never had to repair a failing TJI. I have had to repair them when they were installed improperly, but not from failure of the joist itself. Roof trusses tend to be OK, and I would use them (and have many times), but you can keep your easy to work with floor trusses.  SignatureRobert Allison Rimshot, Inc. Georgetown, TX Thank you for that info. I think I will be ordering TJIs on Tuesday. >> Basement was poured yesterday and I need to order my floor package early >> next week. I see people in the neighbourhood are using open web trusses. [quoted text clipped - 26 lines] > Roof trusses tend to be OK, and I would use them (and have many times), > but you can keep your easy to work with floor trusses. "Robert Allison" wrote in message > Although the trusses will allow the subs to run their ducts, pipes, and > electrical more easily, I will tell you my experience. [quoted text clipped - 17 lines] > Roof trusses tend to be OK, and I would use them (and have many times), > but you can keep your easy to work with floor trusses. I have the same choice for a loft over an unheated garage. I like the ability to run ducts/pipes thru the open web joists, but have been puzzled by the ability to insulate them effectively. Any thoughts on TJI vs. openweb joists for insulation using fiberglass batts? Thanks! > I have the same choice for a loft over an unheated garage. I like the > ability to run ducts/pipes thru the open web joists, but have been puzzled > by the ability to insulate them effectively. Any thoughts on TJI vs. > openweb joists for insulation using fiberglass batts? > > Thanks! Go with the TJIs and you won't have any problems. With floor trusses, the usual method with batts is to insulate between the trusses only, but to fill the space entirely with insulation. This supposedly isolates the spaces between the truss members. SignatureRobert Allison Rimshot, Inc. Georgetown, TX > I did a lot of insurance work for the past 20 years. I have repaired > numerous problems caused by failing trusses. They tend to sag over time > and we have had to go into perhaps 100 separate situations where the > sagging or failing trusses have caused problems ranging from unsightly to > downright catastrophic. Robert, in your experience, was there any common elements among the trusses that failed and those that didn't? Was it related more to installation or more to construction? Thanks, Dennis >>I did a lot of insurance work for the past 20 years. I have repaired >>numerous problems caused by failing trusses. They tend to sag over time [quoted text clipped - 8 lines] > Thanks, > Dennis It was directly related to construction. The joists that sag seem to just slowly, over time, begin to succumb to gravity. I have seen this most in areas with longer spans (16'+). I believe that it is the inherent composition of the truss. Each gang nail plate and each separate component each give just a little, which accumulates to a significant sag of 1 or more inches. The failures have been from various causes. Some have a knot or split at a critical point which fails and overloads the adjacent trusses which also fail due to the added weight. Others have been from settlement of the supporting walls, which overloaded or caused the trusses to bear more than they were intended to bear. Keep in mind that trusses are much like chains, they are only as strong as their weakest link. If you think of how many links a truss has, and every one has to perform perfectly... If only one gang nail, or one component fails, then the whole truss will fail or at least sag. When you are dealing with wood, it is not hard to see how this could happen fairly frequently. Steel trusses do not have this problem because the material quality is much easier to control. Wood has defects and gang nails aren't always perfect or installed exactly right. The problem with them as I see it is that they are not engineered with enough buffer to overcome some very common circumstances. Most people don't want to have 2' thick floors, so the trusses are made as small as possible to stay within expected sizes. This doesn't give them much in the way of forgiveness, so if ANY condition exists which exerts too much force on them, they have a tendency to fail. Dimensional lumber is much more forgiving. SignatureRobert Allison Rimshot, Inc. Georgetown, TX Robert, thanks for the response. Very interesting. These are some of the things that never show up in the design or testing phase. It's got me thinking. Dennis > It was directly related to construction. The joists that sag seem to just > slowly, over time, begin to succumb to gravity. I have seen this most in > areas with longer spans (16'+). I believe that it is the inherent > composition of the truss. Each gang nail plate and each separate component > each give just a little, which accumulates to a significant sag of 1 or > more inches. > Each gang nail plate and each separate component each give just a little, > which accumulates to a significant sag of 1 or more inches. Meant to ask as well, how does steel webs do in comparison with the toothed nail (Gang Nail) connectors? |
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