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How to Install Plywood Underlayment for Vinyl Flooring

Before I share how we installed the glue down luxury vinyl tile in the kitchen, I wanted to share my tips for how to install plywood underlayment for vinyl flooring.  I’m also chronicling the process of increasing the height of our kitchen flooring, by installing a second subfloor.

What is the Difference Between Plywood Underlayment and Subfloor?

Plywood underlayment is one of many types of underlayment installed on top of subfloors to prepare the surface for flooring.  It cannot be used in lieu of subfloor, as it’s too thin.  Plywood underlayment is a thin (ours is 5 mm) plywood.  Unlike the subfloor, which is full of knots and bumps and is pretty rough, plywood underlayment is totally smooth and virtually free of imperfections.  It’s commonly used under vinyl or linoleum flooring.  It’s not typically required under hardwood flooring or carpet, both of which can be installed on top of subfloor with different types of underlayment.

What is Plywood Underlayment?

How Do You Attach Plywood Underlayment to Subfloor?

You can install plywood underlayment with nails or staples, but we opted to use our air nailer and 3/4″ nails.  You can butt together the sheets (don’t force them together too hard), or leave a 1/8″ expansion gap – we chose to butt them together because we will be installing luxury vinyl tile on top.  When nailing down the plywood underlayment, first place nails diagonally across the middle, with nails placed 4″ apart.  Then work out from that center line, nailing diagonally.  Working diagonally this way reduces the chance of bowing.  Then nail along the edges of the plywood underlayment, with nails spaces 2″ apart:

How to Secure Plywood Underlayment to Subfloor

Supplies for Installing Underlayment:

Raising the Floor Height in the Kitchen

We did some extra steps in this kitchen renovation that I wanted to chronicle here.  Once we removed the cabinetry, and replaced/finished the drywall, this is what the kitchen looked like:

Kitchen Renovation DIY

Then we peeled off the old vinyl sheet flooring – which we didn’t really need to do because we were planning on installing another subfloor anyway.  I just didn’t want to picture that crusty old floor underneath the new one.

Removing Old Vinyl Sheet Flooring

Next we cut away parts of the dining room hardwood flooring – scary! – to make the kitchen a bit larger.  In the original plan, the new wall to wall pantry would have straddled the kitchen tile and dining room hardwood.  I decided at the last minute I didn’t want that so, 24 hours before the cabinet installers arrived, we cut away the hardwood flooring.

Widening the Kitchen Cutting Across Hardwood Flooring Boards Cutting into Hardwood FlooringCutting Away Hardwood Flooring

Then we screwed down sheets of 5/8″ plywood, using floor screws.

Preparing Kitchen for New Flooring

We did this because we wanted to raise the height of the kitchen floor to the height of the adjacent hardwood flooring in the dining room and living room (which runs throughout the hallway and bedrooms as well).  There was always a step down, so we sought to remedy that.

Raise the Height of Kitchen Floor

After that, we were ready to install the new plywood underlayment!

How to Install Plywood Underlayment

Like any wood product, be sure to allow plywood underlayment to acclimate in the house for at least 72 hours.  This will minimize any expansion/contraction issues.  Right before installation, thoroughly clean the subfloor with a shop vac to remove any grit or dirt that could interfere with the plywood underlayment.

Modern Kitchen Renovation in ProgressBefore Installing Plywood Underlayment

Installed the plywood underlayment on top of the subfloor, using an air nailer and 3/4″ nails.  As mentioned, you can also use an air stapler and staples.

How to Secure Plywood Underlayment to SubfloorUnderlayment for Vinyl Flooring

How to Cut Plywood Underlayment

Plywood underlayment is very easy to cut as it’s very thin and, in our experience, is sold in smaller sheets than plywood (48″ by 47 3/4″), so it’s easy to manoeuver.  You can cut plywood underlayment with a circular saw, table saw, jig saw – even a hand saw if you don’t have power tools.  My advice is to butt up factory edges against one another and hide the cuts you make at the edges of a room, as much as possible.

How to Secure Plywood Underlayment

To secure the plywood underlayment, follow this process of nailing it down to reduce the chance of bowing:

  1. Nail diagonally across the middle (nails placed 4″ apart)
  2. Work out from the center line to each side
  3. Then nail along the edges (nails placed 2″ apart)

How to Secure Plywood Underlayment to SubfloorPlywood Underlayment Installation Tutorial

How to Countersink Nails in Wood

For any nails that don’t sit nicely below the surface of the plywood, use a nail setter and a hammer to countersink them.  Simple place the nail setter on the offending nail and tap the end of the nail setter very gently with the hammer.

How to Counter Sink Nails

As we worked, we circled any nails we needed to hammer down – you can see one photographed below – and addressed them all at the end, to save time.

How to Install Plywood Underlayment

Luxury Vinyl Tile Uneven Floor Problems?

If you have uneven floor problems and want to install luxury vinyl tile, definitely look into buying a pre-mixed floor leveller and patch.  It helps level uneven floor areas, on wood and concrete, to help ensure a perfect foundation for the tile.  After installing the plywood underlayment, we followed up by applying the leveller along the seams with a drywall mud knife.  We let that dry according to manufacturer’s instructions and then sanded smooth.

How to Use Floor Leveller and Patch Compound

Once we were satisfied with the evenness of the underlayment, we cleaned the dust with a shop vac and followed up with a scrap of old t-shirt wrapped around a swiffer sweeper.  A dark colored cloth helped to see the light dust and we could be sure that it was thoroughly cleaned.

How to Patch Plywood Underlayment Seams

Check back to see our DIY luxury vinyl tile installation!  It looks SO GOOD!

P.S. Don’t Forget to Pin for Later!

How to Install Plywood Underlayment for Vinyl Flooring


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