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Install Plywood Underlayment for Vinyl Flooring

Floors, Vinyl October 2, 2009 Sonia

After establishing the floor break with the outside piece, add material to the inside of the room to complete the install.


Whenever possible, plan your cuts so the factory edges of the underlayment come together, and place the saw-cut edges on the perimeters against the walls. Give yourself 1/8 to 1/4 inch of room along the walls. In fact, you can leave gaps the thickness of the base board. It’s better to have a little wiggle room than to scratch up the walls.

Fastener spacing should be approximately 3″ on the outside perimeter of each piece.


Leave a small gap between the underlayment and showers or tubs to avoid squeaks.

As you install the pieces, move them away from the wall and tighten the joints out “in the field.” When the pieces fit and the joints are tight, tack them in place with a ring-shank nail or with the staple gun.

Bathroom underlayment.


Floor breaks at door openings should line up with the center of the door itself.

Leave a little room (1/16 inch or so) along fiberglass showers and tubs. Even a little floor flex can cause a squeak where the underlayment rubs these fixtures. If you are installing vinyl flooring in a large area where light from a patio door shines across the surface, it’s a good idea to use carpenter’s glue at the seams between pieces to ensure that they stay well connected to each other as well as to the subfloor.

Fastener spacing should be approximately 3 inches on the outside perimeter of each piece.

Nailing patterns should be 3 inches on the perimeters and 6 inches in the field. Before nailing off the pieces in the field, drive a few fasteners with plenty of weight near the nailing spot to make sure the underlayment is against the subfloor.

This utility room floor break is well behind where the bifold doors will be, so the flooring cannot be seen when the doors are closed.

Proper preparation of the subfloor, careful consideration for floor breaks, tight seams and thorough fastening will ensure that your underlayment will provide a good platform for your sheet vinyl flooring for years to come.


Big Cuts/Small Saw

You can cut a piece wider than the capacity of your small table saw by marking the desired width on the piece and measuring to the mark from the opposite edge. Set the saw to cut off the proper amount by measuring to the outside of the saw blade. This approach allows you to use the fence on the table saw for a nice straight cut even though the finished piece (on the other side) is wider than the saw’s capacity.


Cordless Advantage

One of the biggest advantages to cordless technology is being able to easily take the cutting tool to the room where a tricky piece needs to be cut for installation. Some underlayment pieces are like jigsaw puzzle pieces, which makes a cordless jigsaw an ideal tool to make the piece fit the puzzle.

Starting with a basic rectangular piece, you can mark your measurements directly onto the piece as you take them. This avoids the need to write down measurements or to draw a diagram. You can cut out openings*, make adjustments, and test fit your piece without ever leaving the room.

*Tim, you really should use a sawhorse for this operation.