Can I Use Sanded Plywood for Sheet Vinyl Underlayment?

Underlayment

• Sanded plywood’s multilayer construction, which makes it puncture resistant, as well as its strength and stability make it an excellent underlayment material for sheet vinyl. According to the Engineered Wood Association, underlayment-grade plywood is available with touch-sanded or fully sanded facing for a smooth finish. Among the grades recommended for use as underlayment are "plugged" with a sanded or touch-sanded face and sanded plywood marked "plugged crossbands under face."

Preparation

• Bring the plywood indoors 24 to 48 hours before you lay it to acclimate it to your home’s heat and humidity. Lay out the sheets so all the grain goes the same way. The plywood grain should run perpendicular to the grain of the subflooring underneath. Halex Corp., which makes flooring installation products, recommends offsetting the plywood so that four corners never meet. Factory-cut ends should butt together. Cuts you make yourself should face the walls.

Spacing

• Some expert sources, such as the Engineered Wood Association, recommend leaving gaps between plywood sheets and leveling them with a filler approved for vinyl. Other sources, including Armstrong and Ask the Builder, warn that fillers may discolor the vinyl. Armstrong recommends lightly butting edges together without leaving a gap or using a filler.

Fastening the Underlayment

• Fasten the plywood with underlayment nails about the same length as the plywood and subfloor so the nails go through the subfloor but don't extend beneath it. Space the nails no more than 3 inches apart around the perimeter of each plywood sheet. Sand any unevenness between adjoining sheets, as ridges will show through the vinyl. Also sand any other uneven or raised areas. The vinyl needs a smooth, perfectly flat surface to adhere properly. Remove all dust before you install the vinyl sheeting.