I have a 4 year old house, ranch style with a finished basement. My floors are truss construction on 24″ OC, with exterior grade 3/4″ OSB sub-floor. I’m wanting to install 3/4″ pre-finished hardwood floors, but I’ve been told by one flooring installer that it is too much of a load for the floor to support. Any thoughts would be great.
BIll
Replies
How deep are the trusses? What span are they covering.
24"OC?? Wow.
Samt
My gut tells me you won't like it if you do, too much movement!
I'm surprised there isn't a sag in the floor between trusses, with 3/4" OSB spanning 22" or so.
Subject to load restraints, I'd use 3/4" hardwood, glued down with a flexible adhesive like Bostik's Best, perpendicular to the trusses. I'd still expect a bit of sag even so.
IanDG
Your subfloor is inadequate for a 24"oc layout. it doesnb't much amtter wjhat sort of foinished flooring you use, you need top glue and screw another 1/2" or 5/8" of underlayment. I suspect there may be p[laces that you need blocking of some kind under partion walls too.
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Before this thread gets carried away, I've got the same situation, but still unbuilt. Are you guys saying that floor trusses 24" O.C. is too much? I'm using Open Joist 2000 floor trusses by Universal, 24" O.C., 11-7/8 depth, maximum 14' span. I had planned on using 3/4" T&G ply, not OSB, followed by 3/4" hardwood flooring. I would think that's fine, but maybe I should run the joists to 19.2"?
depending on how they were engineered, the trusses themselves can be fine at 24"oc, but the subfloor to span the distance between them needs to be 1-1/8" Advantec or similar made for subfloor applications. or it needs to be 3/4" plus 1/2" or 5/8"
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Agree on the first part.
If you put 3/4" hardwood T&G perpendicular to the trusses and if those strips are long enough, wouldn't that be even better than putting another layer of 1/2" or 5/8" and put say carpet over it? Of course it would be much better to put the 1/2" or 5/8" then the hardwood, But I am thinking may be we can skip the 1/2" or 5/8" in this case.
That could be the case but there are some bog IFs in there.
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Take this test, put the heaviest thing you think will ever be placed on the floor. The leg of a fat lady in high heels? a piano leg, two fat drunks?
Ok let's pick two fat drunks say 250 pounds each, both standing there toe to toe and shaking hands. That's five hundred pounds. Put it so it will span the joists (worst case) will there be deflection? In my experiance you bet your bippy there will be!!! and if it occurs often evan to a small degree that movement will cause the nails to loosen and the floor to squeek. eventually the floor will wear out long before it should..
Ok, this is what I found out from city code enforcement, builders in the area and the hardwood floor manufactures.
First code enforcement and local builders - the floor truss construction vs. joist: Area code for floors goes with 10/40, they must be able to hold 10 pounds dead load and 40 pounds live load per square feet. 2x joists at 16" OC = truss at 24" OC for the same load limits with 3/4 sub-floor (OSB, Ply, or superior). I've already tiled the kitchen, (1/4" concrete board in thinset and screwed down, anti-transfer membrane, tile, 12" & 6", in thinset). This has created a rock hard sturdy surface with no problems after one year.
Harris Tarkett & Armstrong - Both fully warranty their 3/4" T&G product over this truss 24" OC with 3/4" OSB substrate, as long as their product is installed perpendicular to the trusses. Harris Tarkett would not fully warranty their 5/16" wood floor products over my type of floor construction, due to deflection, without an additional layer of substrate added.
Thank you for all your comments.
I'll be going with the 3/4" T&G pre-finished, unless someone here has a bad experience with this exact type of floor construction and hardwood floors.
Bill
you are talking about two different span/load scenarios here.
One is the joist or trusss system. i have no doubt that the trusses can handle the loads.
The questiuonable part though is in thge span between each truss that the ply has to cover. I don't know what is meant by the ply manufacturer covering a warrantee. That usually means that it won't delaminate, noit whether it will meet engineering needs.
The other thing you need to be aware of is that codes adress a MINIMUM allowance and do not seek to adress a QUALITY standard. codes cvary from one place to another. I am not under any building code but I design to a 15# dead load and a 50# live load. This is what is required in many localities for living and lithchen areas with the lower standar you quote being allowed in bedroom and storage areas.
Just something to keep in mind. Go intpo this being aware that you are building to the MINIMUM and you may not be happy with it in the long run. That's your choice. Good luck.
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I absolutely agree with your advice about building to a minimum standard rather than to a high quality standard which we should be advocating at a FH website. If you are doing something for yourself and are willing to accept the consequences, that is one thing. The minute that you are working for someone else, if you work to a minimum standard, you will always be going back to fix problems that come back to bite you in the rear. Who wants to do that?