I am ready to replaced vinyl with hardwood flooring in our 10 yr old home. The home was built using 2X4 open web floor trusses which I thought were great as all the wiring and HVAC run through them and will make finishing the basement a breeze. Now that I'm ready for new floors the problem I may have is that they are 24" on center with a 23/32 OSB glued and screwed subfloor. All the reading I have done indicates that this may not be the best subfloor for hardwood. I do notice some 'bounce' in certain areas of the floor. I am considering using 2X4s on edge (sistered) on each side of the floor trusses with 2X4 blocking in between these at 16 inch spacing. I figure this will add a little weight but also strengthen the joists. Will this work? And if so, can I then install the flooring parallel to the joists as I will have the blocking at the specified intervals (it will look better this way)? BTW - I am looking at Brazilian Cherry 3/4 X 3" flooring.

If you correctly (key word here: correctly) install that 2x4 blocking between the truss bays 16" oc, you should be able to lay your 3/4" T&G flooring parallel to the direction of the trusses. However, since the top cord of a web truss is laid flat instead of on edge, how will you securely attach blocking to the trusses? I suppose you could toe nail or screw and use some subfloor adhesive. Another option you may wish to consider is to overlay your subfloor with 1/2" CDX. This will stiffen things up considerably and allow you to run the flooring in any direction you choose plus gives you a much better substrate to nail/staple to.

Gary - Thanks for your reply.

Yes - had planned to toenail the cross bracing (and nail through the new 2X4 into the cross bracing where it was below the top 2X4) and use adhesive as well as screw from subfloor from above after removing the vinyl. I wanted to do this rather than adding the additional plywood on top in order to avoid raising the height of the flooring anymore. Was also worried about the additional weight on the trusses. I have kitchen cabinets that I would like to floor around rather than remove and replace on top of hardwood, and the new flooring will need to transition into carpet as well as tile which seems like it would be more difficult if I have to deal with the additional height. Is this OK or do your think it would be better to deal with the additional height and add plywood to the subfloor?

Next time I will make sure floor joists are 16" on center (if I ever build another house)!

The 1/2" plywood would not be an issue weight wise. It isn't heavy and it does hold fasteners better than OSB. However, OSB is an acceptable subfloor for nailing to and if there is a height issue then go with your plan. I think you will risk sqweeks unless you use a good subfloor adhesive. I would lay the 2 x 4 blocking flat against the subfloor after applying a generous bead of glue. Then pre drill to screw (with 3" screws at an angle) into trusses. Cut the blocking 1/16" oversize and pound into place (pressure fit). If they are loose and too short, they will serve little purpose. Then screw with 1&1/2 screws into blocking from above. You could add an additional 2x4 below the block that overlaps the truss and screw to that to ensure a good joint. Sort of like a gusset.

Sounds like a plan - thx again for the advice.