How to attach plywood to subfloor

Billdd

I have a 1/2 inch plywood wood subfloor in the kitchen, I removed the 5/8 inch; particle board and I am installing 3/4 T&G plywood on top of the 1/2 inch plywood. Should I glue the 3/4 plywood to the 1/2 inch plywood subfloor? Do I screw into the floor joists? Do I put a layer of 15 lb felt between the two plywood layers instead of glueing. I plan on putting 1/4 inch underlayment on top the 3/4 inch and glue vinyl tile to it with grouted joints. (wife wants grouted tile, not my choice.

firstimereno

bill - i'm a DIYer too, but have already been through that step, and have done vinyl before, so thought i would share some info.... (i'm having so much trouble with real tile i'm about to rip it all out and go back to vinyl)

if you ever have a leak, replace the floor covering, etc... if you glue the upper layer to the lower layer (the layer that runs under your stud walls, attaches to your floor joists) then in future lower layer would have to come out, too. either ring-shank nails or screws. that will be plenty, especially since you're going with t&g ply.

what you need is lower 1/2, upper 5/8 or 3/4, then BC grade or better underlayment. just remember all these layers are adding up, and in most cases, 1" total is plenty for any floor. watch your heights as they meet with other floors...

firstimereno

hey, if "luan" scares you, then step up to 1/4 ply. your underlayment (if 1/8 or 1/4) can be narrow-crown stapled to the top layer of ply and act as underlayment. of course, seams and staple tops need to be covered with filler/prep product as well.

bill, the main goal with vinyl is a flat (leveler compound, if needed) and SMOOTH (both important) substrate to attach the vinyl. you already are at 1" on the wood, but you will still need the 3rd layer. BC grade is a clearer grade, and is sold along side the std stuff at lowes/hd. it is used for veneers, cabs, furniture, etc. it is much smoother and clearer (less knots, pitch, etc) than std (CDX) grade stuff. the first two can be CDX, but underlayment needs to be better grade. if your tiles are self-adhesive type, your wood better be super-clean. don't lay down your underlayment 3 weeks before you plan to vinyl, you're just causing yourself more prep cleaning when it comes time to tile. if you do have to put it down ahead of time, cover it with butcher paper or something (but don't tape it to the wood)

joecaption

I by far have heard more complants from my flooring guys and my supplyers about this viny ltile with grout. The grout cracks, skip on the subfloor and underlayment and get to have to do it all over agin.

rusty baker

Make sure that 1/4 ply is underlayment grade. Regular 1/4 ply can have voids and can collapse.

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"I'm twisted, not sick. Sick implies, I'll get better"
Semi-Retired Installer
Installing since 1973

firstimereno

bill, i totally agree with joe... i would steer clear of the grout+vinyl tile scenario. vinyl tiles WILL shrink/expand, no matter what the manufacturer might claim. UV, heat/cold, and simply the aging of the material itself can all wreak 'slow, silent havoc' on the tile... and when it happens, that beautiful grout will be a distant memory. not to mention if any future settling, contraction/expansion w the house floor framing, subfloor, etc occurs. proceed w caution when moving the appliances back in!!

Gary in WA

http://www.apawood.org/pablog/index....-Floor-Systems

http://bct.nrc.umass.edu/index.php/p...ient-flooring/

http://www.apa-europe.org/Languages/.../PDF/R340G.pdf

Gary

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