Hardwood floors over 24'' oc trusses

[Daniel]

I would like to install solid hardwood floors in my one year old home. My subfloor is 3/4'' t&g sturd-i-floor rated osb over engineered floor trusses spaced 24'' oc. Bruce hardwood says they can not recommend installation over 24'' oc spacing due to excessive deflection. My builder says they install the same floors in their houses without problems. Does anyone have an opinion as to the suitability of my home for hardwood floors? Does anyone know a way to stiffen the floor using the existing trusses?

[mjpliv]

Your main concern would be maintaining your warrenty for the Bruce Flooring. Contact the Bruce Flooring rep and see if they will consider covering your product with a second layer of subfloor. This will mean creating havoc with standard door heights and you may have to adjust your stair risers to accommodate the extra 5/8" or 3/4".

Ideally, this floor should have been sheathed with 1-1/4" osb where the joists were spaced at 24" OC. Even still, you may find some hardwood flooring manufacturers reluctant to warrenty floors installed over any OSB product because of performance concerns either real or imagined. Its always best to check first.

[Daniel]

Thanks mjpliv for your reply, actually 3/4'' Sturd-I-Floor rated osb is one of the "preferred" sub floors for this manfucturer and the only single layer osb sub-floor approved by the APA for hardwood floors. The problem, as Bruce Floors sees it is the 24'' joist spacing and resulting deflection. An engineer at the the wood truss council of america suggested I use 2x4 's between the top cords of the trusses, glued and nailed to the subfloor from below to stiffen the floor. Any thoughts on this idea? Also, I would like to recommend the WTCA's web site to any homeowners with engineered wood trusses.

[mjpliv]

What did you use for joists? 2X's or and engineered system?

[JCA]

I have trusses on 24" center(attic frames) (a decision I regret by the way, really wish now they were 16" o.c.) so I install 3/4" Advantech T&G OSB first and then 5/8" floor sheathing plywood over that. The result was very impressive. Before the plywood I could feel the deflection in the OSB, now it's solid as a rock. I also installed strongbacks between the trusses at the outside edges of the floor to stiffen the edge. It seems to me that the 3/4" hardwood would take care of any deflection on it's own.