Trusses vs Solid Floor Joists

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Old 08-03-06, 08:52 AM
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Trusses vs Solid Floor Joists

We are looking into purchasing a modular home and one of the big differences I see (from a "site built" home) is the use of trusses. In particular, I am questioning the strength of the floor joist trusses which are made from 2" X 3" stock. The manufacturer is telling me that these are actually stronger than a solid 2 x 10 joist! I'm not an engineer but just looking at theses things makes me question the quality. So what is the deal with trusses vs solid joists or rafters? Should I be concerned? Are trusses stronger?

Thanks so much in advance for your input.
 
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Old 08-04-06, 11:40 AM
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It is like building a bridge. Trusses will always be stouter than a single framing member. Now, there are several type of trusses out there. Z-type trusses made of 2x4's with alternating angles of other 2x4's, all tied together with nailing plates. These are great because you can usually hide your plumbing, wiring and HVAC up in them and leave a full ceiling in a basement.
There are also Silent Floor type trusses made from a grooved 2x2 on top and bottom of a 9, 10, 12" web of OSB. These are very strong and can span 26' without any center support. They also have perforated knock outs for wiring, etc.
I have seen these made and they are glued and pressed under steam pressure and are only cut at 65' because that is how long a box car is. Otherwise length is not a problem, as they are made in a continuous 24-7 run.
 
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Old 08-05-06, 03:32 AM
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Trusses

Thanks Larry,

The trusses under these modular homes are made from 2x3 lumber (not 2x4). So this would make them 2 1/2 inches wide vs 1 1/2 wide for a solid joist. Are you saying that the extra width will make up for the lack of a solid framing member?

Thanks
 
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Old 08-05-06, 03:34 AM
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Oh... and they are in the "Z" formation which you mentioned.
 
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Old 08-05-06, 04:34 AM
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It is the Z not the wood size that gives strength. Believe me, they were engineered with two things in mind: strength and economy, and neither was skimped on. If the wood is smaller, then the webbing is more intense to make up for the size.
 
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