engineered Plywood I Joist

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Old 01-04-10, 08:24 PM
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engineered Plywood I Joist

I am building a 16'x16' 2 story cabin on some property we own.

I need to span the first floor to support the 2nd story loft.

I was looking at engineered I beams, but it really looks like they are something I could build myself to save some money.

Any reason I cant rip some 1/2" plywood into 12"X8' strips and then make the top and bottom of the I beam with 2"x4"?

I looked on the net for a similar project, but I couldn't find a DIY example. It looks easy enough. Just cut a notch in the center of the 2"X4" about 3/4" deep and 1/2" wide, apply a waterproof wood glue and sandwich the plywood in the slot. Clamp and wait to dry

Would this work?
 
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Old 01-04-10, 09:02 PM
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No it would not work.

 
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Old 01-04-10, 09:36 PM
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Originally Posted by XSleeper View Post
No it would not work.

So how would I build my own I beam to span a 16' room?
 
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Old 01-04-10, 10:26 PM
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First you would get a degree in engineering... only partly kidding.

Engineered I-joists are just that... engineered. The web is not made up of 8' pieces of osb... it is made of one solid, continuous piece so that there are no seams. And the top and bottom pieces are not just 2x4's with a dado cut in them, they are engineered wood. The glue used is not just wood glue, it's probably some special epoxy. Making your own i-beams probably isn't something you should even consider. Especially since anything built in a sub-standard way will come back to haunt you, if not sooner, then later.

I don't see why you wouldn't just use 2x12x16, 12 or 16" OC, depending on your needs.
 
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Old 01-05-10, 04:59 AM
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The TJI silent floor beams are just as Sleeper says....engineered. They are made in their own factory and the OSB product is glued and put under pressure, as well as the layered top and bottom pieces. Then as a unit, they are run through heat sensitive glue and a heat/pressure chamber where they are pressed under heat. They are cut specific for the job length, or for shipping in bulk they are cut 63 feet long, as that is how long a rail car is. Otherwise, there is no practical end to them, as there are no seams.
You could use LVL or dimension lumber, either of which may be less expensive and more eye appealing. However, if you have wiring, heat, etc to run between the floors, the TJI or similar I beams are already set up for knock outs where you can run them.
 
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Old 01-05-10, 05:36 PM
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Put a plywood beam in it. My secret until now: http://www.forestryforum.com/board/i....0;attach=1494 Run your joists on top, back to the shorter span.

I built one back in '78, far as I know it is still there.....

Be safe, Gary
 
 

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