How should I prepare a plywood subfloor for floating vinyl plank flooring?

Question

The floor of my laundry room was three layers of hideous vinyl flooring of various vintages, a layer of 3/4" plywood underlayment (to match the height of the vinyl to surrounding hardwood flooring) and a subfloor of diagonal 1x6ish planks.

I removed the vinyl and replaced the rotting plywood. Now I'll cover the plywood with interlocking vinyl plank flooring of this type. The instructions are written for covering an existing flooring material, so they don't address preparation of the subfloor.

Although the vinyl planks are waterproof, it doesn't seem right to lay them on bare plywood, particularly in the laundry room. How should the plywood be prepared? I think I'll just paint with Kilz 2 and caulk gaps and seams.

Answer 1

I'd question how waterproof you need this to be. Will there routinely be water sitting on the floor? If not, you may be over-engineering things.

That said, off the top of my head, one option for waterproofing the subfloor would be to paint on Redgard:

It's a 'paint on' waterproofing membrane that you'd typically use behind tiles on cement board and the like.

Answer 2

A little late to this thread, but I could help but wonder...

Is that rotting plywood you speak of due to moisture from your washing machine or other top-down sources, or is it likely due to the moisture seeping up from your concrete subfloor?

If the moisture is coming up from the concrete, you've got bigger issues on your hands. The moisture will continue to rot whatever you put on top of it, so you really must seal the concrete first, or find out if you've got a leak coming in from a wall somewhere.

Moisture from the top of the floor usually comes from: a) Large spills of water b) High moisture content in the air

With problem (b), a great solution could be a dehumidifier. Suck that moisture out of your air and keep the humidity around a constant 50/60% RH in order to stop mold and mildew.

If it's problem (a), it's really hard to find any click-lock flooring that will seal completely and not let moisture through ANY crack. You just have to be very proactive and fast in mopping up spills or floods. Even a little water sitting for too long can make bubbles happen in cheaper laminate floors or cause cupping in hardwoods or engineered woods.

No matter what you lay down, it's going to cost time and money. If you're interested in really the ONLY way to protect that investment...ie in the case of a large floor or really big spill, you really want a system that you can remove without damaging the flooring. That way, in the case of a big moisture problem, you get all the damage prone wood out of there, clean up the mess, and put it all back again.

Really the only think I've seen that can do that is a new solid hardwood system called Easiklip. It's a floating 3/4" hardwood that just sits on top of a standard underlay (i think). It uses a new clip system to attach boards to one another so nothing is ever nailed down. You can actually pop it up again once you've laid it. So in theory, if there's a big flood, you just pull up your flooring, dry up the mess and put it back down again.

Kinda cool and maybe worth checking out :) Here's a link to some installation instructions for the Easiklip system - take a look at the clips Easiklip Installation Instructions

Hope that helps!

Answer 3

Your floor needs to be clean and flat for a floating floor. To cut down on squeaking I would have glued and screwed in the plywood.

I am currently putting this floor in my basement. It is a great waterproof material. Not sure where you are going with Kilz2 though.

If you want the floor to be waterproof or have waterproof qualities then the water needs somewhere to go - a drain. If you just want to hold the water on top of the flooring well you could do a paint on waterproofing agent like redguard. I think it is overkill though.

The manufacturer does suggest no underlayment with this - probably worried about moisture trapping under underlayment. If you have large gaps - bigger than a 1/4 inch I would use a leveling agent to fill them. If they are small I wouldn't touch them. If you are looking to trap the water on the top of the flooring so it doesn't get to the subfloor then make sure your planks are tightly clicked, your baseboards are pushed down on the floor and caulk the gap between baseboard and flooring.

Answer 4

I am doing a similar installation now, however my plywood sub flooring is pressure treated. I am filling any gaps with silicone caulking and then using an approved leveling/patching material(Henry Unipatch is what I'm using). I am then going to coat the entire floor with a bonding agent. I have 475 Sq. ft. of floor to do.

Answer 5

Strip the old with a flat spade shovel or similar and put down ceramic tile that is cheap and hides dust with a satin finish. The flatter the surface, the bigger your ceramic tiles can be up from 12 to 16". Gap each piece with as small a gap that you can keep straight without notice. Notice the gap in car doors is smaller these days due process control. I prefer almost no gap for grout or adhesive fill. With sufficient adhesive there wont be any air gaps that create a hollow sound if you drag a chain over the tile when done promptly.

No more rotting plywood and easy clean floors that last decades. A fan helps accelerate concrete dying or a bonding concrete can give excellent adhesion unless the floors are cracked.

If basement floors get damp from seepage and cracks, , plastic ventilated panels are an option for subfloor, but that may be a warning the weeping tiles are plugged.

Answer 6

Installed TrafficMaster Allure Ultra in my bathroom a year ago. Put it straight on top of existing ceramic tile with no problem. Used Henry leveling compound to fill a few depressions and then laid the tile. It's held up great and looks just like wood.