7 year old house w/Oxboard floor. sagging between TJI question

i ran a google search for this, and came up empty. . .so i'll post this and wait for the flame. . . *G*
my wife and i bought a home 3 years ago. at the time, the floors were rock solid and squeak free. since then, in the high to medium traffic areas we have noticed sagging in the floor between the TJI. . . the spots directly over the TJI are solid, and it seems that it is limited to certain sheets of the Oxboard. IE: you can sag on one sheet, and feel the seam with the next sheet and that one is solid.
what are my choices here. i am contemplating ripping up the carpet and overlaying with 3/4" ply gloo'd n' scroo'd. is this my best bet? i don't really want to rip out the finished ceiling in the downstairs. or, in the long run, is it going to be cheaper and easier to do just that and place cross members between the TJI?
TIA Traves
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On Mon, 11 Aug 2003 22:41:38 -0500, Traves W. Coppock

Generally yes, but laid in the opposite direction from the original plywood.
HOWEVER, you haven't given enough information for any to tell you what to do. Any idea how big the joists are ? What span ? What is the subfloor made of and what thickness ? Under the carpet you should have a second layer of wood as a finish floor above the subfloor: Is it there, what is it, what thickness ?
What's "TJI" and "Oxboard" ?
Bob
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what is the spacing of your TJI? If this is truly particly board and not OSB style wafer board than you are in trouble, as it should be used as an underlayment ON TOP of 3/4 OSB or Plywood.
TJI are great for the spans but I would never space them greater than 16 on center as some builders do.
wrote:

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the shop and said. . .:

2' on center for spacing, as is code here. as for the oxboard, yea, its like OSB, but its the tongue and groove flooring stuff. hehe as for being in trouble, the floor is sagging already, and i anticipate many troubles ahead anyhow :)
Thanks, Traves
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OSB comes tongue and grooved too for flooring but is much stronger than particle board. Plywood also is available tongue and groove for flooring. If the stuff doesn't say it is OSB and it looks like particle board you definitely have a problem but it sounds too dumb of mistake to have happened. It should say OSB on it.
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On Thu, 14 Aug 2003 01:29:47 GMT, "Art Begun"

it IS a brand of Oriented Strand Board. i chose my original wording poorly. so what would make this stuff lose its structural integrity, and what is my best course of action to make this kind of repair? rip it all up and start from the bare "joists"? or a plywood overlay?
Traves
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On Wed, 13 Aug 2003 20:58:48 -0500, Traves W. Coppock

Traves:
If I understand what you said in your followup post, you have the OSB on top of 1/2" ply ?
1/2" ply is too thin to span 2 feet. I assume this all met code at some point, but I don't see how. But, it's there now so you need to work with it. Ripping everything down to the joists does not make sense and would actually lessen your structural integrity. I would pull up the OSB "finish floor" and put 3/4" t&g on top of the 1/2" subfloor layed opposite to the plywood, screwed and glued. Normally that would be done in reverse order with the 3/4 on the bottom, but you have to deal with what's there.
Bob

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