Subfloor advice needed

Diogenes · 10-02-2011, 04:32 PM

Hello,

I need to put down a hardwood floor in a bedroom and I'm not entirely certain that the subfloor is adequate. The subfloor is 1X12 boards (3/4"X 11.5") nailed to 16" O.C. joists. There are gaps between the boards up to nearly 1/2" but genrally 3/8" or less. The hardwood I'm nailing down is 3/4" American Cherry with boards ranging in length from 11" to 48".

I've already taken down a significant hump in the floor by removing four of the 1X12's and planing down the joists. All the 1X12's had a center crown which I have planed and sanded down to a flatter state. I still have many spots where there is an elevation difference between abutting floor boards and there are still some humps. I have also put a lot of screws into these boards to tighten things up.

I've been working on this floor for days now and no way will I be able to get it perfectly even or flat, but assuming I get it to a tolerable state, is it still even avisable to nail hardwood to such a subfloor?

It's an upstairs bedroom and I'm working by myself and I don't have a truck, so lumping in sheets of plywood would take some doing.

Thanks very much for any advice. Apologies if this is a bit long, but I wanted to be specific.
-Nick

JazMan · 10-02-2011, 07:34 PM

Hi Nick,

I think you have more work to do. You need a layer of plywood over those planks. That floor was not built with hardwood in mind otherwise the planks would have been installed on a diagonal. Your new hardwood planks should be installed perpendicular to the joists, the same direction as the 1x12's. Hence why you need plywood.

If you're satisfied with the condition of the planks, (doesn't sound good enough to me), 1/2" ply might do it. Thicker would work better though.

Jaz

Diogenes · 10-03-2011, 07:18 PM

Jaz,

Thank you very much for the reply. You confirmed my suspicions.
I will proceed with your advice in mind.

Thanks again,
-Nick

tacomafloor · 10-03-2011, 11:48 PM

Agreed ,,, 1/2 plywood or osb oriented strand board,,over the top of the planks , With the strength axis across the joists ,and ,,not that cheap particle board
tacomahardwoodfloors.com