I would like to install 3/4" hardwood. The subfloor is 3/4" plywood and I need to put sleepers (ripped 2x4's) on top of the plywood to level it out.

The hardwood would be installed perpendicular to the 2x4's and the 2x4s will be laying flat with the 4" side down. If the sleepers are spaced 16 inches on center, could the hardwood be installed directly on top of the sleepers or would an additional layer of plywood be needed?

I am really trying to minimize weight so that's why I'm asking.
Thanks

you can but I am always afraid of the hardwood sagging and it's also more work needing end seams to land on the sleepers. As for weight the plywood wouldn't add any more then 1lb per square foot depending on the thickness.

Would 1/2" plywood be strong enough to prevent sagging?

Also, what is the best way to rip 2x4's going the 4 inch way?

How out of flatness is your subfloor? Sounds like your creating a small nightmare, and really raising the height...

Thanks for the reply. The floor is out of level by a lot -- as much as 1.5" over a 6' span in the worst spot. A structural engineer designed a fix to strengthen the subfloor to prevent any further deflection.

The additional height will not interfere with doors, etc. partly because I removed the old underlayment and parquet which were together an inch in thickness.

Which part of the approach do you think is nightmarish?

Kinda bothers me to have that pocket of space, sandwiched between the subfloor and the underlayment. That space is going to be directly under your finished product. I may worry about conditions resulting from lack of air movement etc...

I don't know if this is an option without seeing it.......Taking up the subfloor down to joist, and shimming the joist.

Sometimes we try to solve a problem by adding to it....instead of fixing the cause.

if u don't want to add plywood, do the sleepers 12"OC....you will be fine..

As long as its oak or other hardwood..no issues..Pine is usually not end matched, so ends would have to land on sleepers..

Thanks for the information Floorologist and JamesTRD.

@Floorologist I know what you mean. Problem is, I live in a condo and I don't own the subfloor or floor trusses (joists). The condo association had their contractor/engineer reinforce the trusses in the sagging position. They refused to jack-up the trusses for fear of damaging the rest of the structure. So, they've screwed me and now my options are limited. I could sue but a lawyer has told me that litigating may cost more than trying to fix the problem myself. The condo board refuses to help, so I'm on my own. My objective is to do the best I can without incurring huge costs, but I don't want to do anything that will screw the next owners either.