Replies

1. 
   Guest_ | Jun 22, 2000 08:08am | #1

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   Doing it yourself? TJM

   Hiring it out? TJI

   I hope my answer is adviceful

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   Guest_ | Jun 23, 2000 06:29pm | #2

   *I just used steel Joists in a retrofit on my house and loved them. This was a surprise to me because I always thought "wood is better for a residence" but the advantages of steel should be considered:Very light weight (great for remodeling in an existing structure when static load might matter more).Low cost (in my case they were cheaper than 2x lumber, eliminated some hangers and were much cheaper than TJI.TJI may not last as long in a fire as 2x would (less mass, more surface area), but steel won't burn - though there could be an argument when high heat melts them, wonder if anyone compared this (y'know, short term, super high heat, fire-fighter type situations when wood's insulation value could help or something...).Aside from that I figure, after the floor is on and the insulation in, I'll never know there's no wood in there. The down side to steel is work ability: an abrasive blade cut the joists in about twice the time to cut SPF (10 sec vs. ~5 sec in 2x8's) and the blade did not last as long as a carbide tipped would in wood. Screws had to be used for attaching, and they cost more than nails and I had to pre-drill because of my strange design. I think simple floor joists could be hung more easily, using factory made holes.But a workability advantage steel had was really neat pre-made holes for wiring, plumbing, HVAC, etc. The holes are flanged and provide great grab handles during construction.I don't know if this was what you wanted to find out. If you wanted to compare span loads or how springy your floor would be you have to study the manufacturer's tables and consult an engineer.

1. 
   Guest_ | Jun 24, 2000 03:48pm | #3

   *I've always heard that the wood product has a higher fire rating than the steel, but I can't verify that with an authoritative source.Hopefully, Ron S. will jump in here with a clarification.Steve

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   Guest_ | Jun 25, 2000 03:07pm | #4

   *Steve, Fire resistance is a hot topic with trusses and TJI's. I would honestly have to say I don't know what the truth is. I've heard that steel joists are thin guage, and can fail quickly in a fire. But they also don't burn, and so don't contribute fuel to a fire. TJIs have a thin web which can burn through quickly. Floor trusses have open webs, which lets fire travel sideways more easily. (Although this really only applies if there is a finished ceiling hanging below the floor system)What floor system out there is really made to survive a fire? Who designs their house to be fireproof ? All floor systems have their problems. On a side note - I've bid 2 jobs in the past 2 weeks that were firehouses with wood roof trusses in them. So maybe the fire service doesn't think that wood trusses are all that bad ?

1. 
   Guest_ | Jun 28, 2000 05:07am | #5

   *I'm a little confused, are you talking about using TJI's or steel joist's, or TJI's or metal web joists?One has an OSB web, one is all steel, the third has metal webs pressed into the sides of the 2x flanges.

2. 
   Guest_ | Jun 28, 2000 12:41pm | #6

   *I was talking about TJIs vs. all steel joists vs. floor trusses. I was lumping wood web floor trusses and metal web floor trusses together.

3. 
   Guest_ | Jun 29, 2000 12:05am | #8

   *Ron, I've never used all-steel joists, but have used all the others. You will get similar results from all three. With TJI's if you have cantilevers and bearing walls the blocking can be time consuming, where as with a web-truss they are designed for the specific use and have the necessary blocking etc. built in. Open web trusses are nice for mechanicals,(a little more work for cold-air returns though). Open web trusses can also be designed for top hanging, allowing for flush beams without hangers, or another row of block around the perimiter if grade height is an issue.JLC had an article recently on bridging and lateral bracing of TJI's for strength and vibration resistance you might want to check out.Good luck, Steve

2. 
   tjc12 | Jun 29, 2000 12:05am | #7

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   I am hoping to build this summer and cant decide which floor joist to go with. Would any one have some advice for me. I have a 32ft span and will use a beam in the middle. Thax TJC