Hello All,

For the last several weeks I've been reading every single thing I can get my grubby little hands on regarding nail-down floor installation. This forum is an incredibly valuable tool with a wealth of information.

The house situation: my wife and I have proudly purchased our first home: a 1981 split-level in Renton, WA (just south of Seattle on the east side of Lake Washington). In preparation to move in we've undertaken a fairly substantial remodel. So far I've pulled down the popcorn ceiling texture, painted and ripped up the old floor. Previously there was a nasty laminate in the living / dining area and upper floor hall and carpet everywhere else.

The sub-floor situation: With the old flooring up I'm looking at an entire floors expanse of particle board panels. I've cut a small chunk out and measured it to be 13/16" thick. I've pulled a number of heating registers and have not seen anything between the particle board and the joists and at this point believe that the particle board IS the sub-floor.

My proposed fix: Of all the research I've done I have read that, if in fact the particle board IS the sub-floor, the particle board should be left in place and a layer of 1/2" CDX plywood should be glued and screwed over the particle board. I have cut and laid out 1/2" CDX plywood over the entire upper floor. Before I go to finally glue and screw everything down I have to work to do some flattening. The sub-floor slopes rather dramatically from the center of the dining room, through the main hall, to the far exterior wall of the bedrooms.

I have sitting in my garage 1200 s.f. of 3/4" maple that I plan to nail down. I want to make absolutely sure I'm doing this the right way before I even think about nailing my first plank.

Finally I get to the question: is my proposed course of action (1/2" CDX plywood over the 3/4" particle board sub-floor) the best course of action for treating with the sub-floor? Any and all help would be much appreciated.

Thanks!
Charlie

As soon as you get some of that plywood down you need get that floor out of your garage and inside the house. Next check the new subfloors m/c and wait till its withing two points of your finished floor to minimize movement after installation. as far as the leveling goes doit before the ply goes down as needed to bring into spec.

Hi Kevin,

Thanks for the quick reply. My plan was to get the floor inside as soon as I could and verify MC as you indicate. Just to confirm, the 1/2" CDX will be acceptable over the particle board sub-floor?

Thanks!
Charlie

Yes, the 1/2 inch is fine, and as Kevin says, it is extremely important that the floor be brought into the house as soon as possible.

Excellent, thanks! I hauled 24 boxes of the wood into the living room last night (the only room with plywood glued & screwed at the moment) and opened them to allow them to start acclimating. I'll have my hands full bringing the underlayment to within spec so the wood will have ample time to adjust.

He hopes your plywood is not being brought up from the garage and immediately installed without acclimation.

Out here it's so dry I kinda do the kiln drying sticker thing. Cut up strips and lay at least four in between each sheet to air dry.

Started gluing and screwing the second layer of plywood to the first in the lower level of the house. I have the two layers laid over a 6 mil vapor barrier over the slab. I've noticed that after gluing and screwing two panels that after walking on them I can hear the vapor barrier crinkling.

Is this likely to improve as more of the plywood is fastened together? Is the noise likely to diminish once the floor is in and things have had a chance to settle? Should I just bite the bullet and put a layer of felt over the vapor barrier?

Thanks!
Charlie