Can I Use Plastic as Underlayment Over a Cement Floor?

Prepare the Cement

• Do not lay plastic underlayment over a dirty or uneven cement floor. To level up a cement floor, you can either pour self-leveling compound over the floor’s surface and allow it to settle into the dips automatically, or you can find the dips in the floor with a level and fill those dips individually with leveling compound. Once you fill in the dips, clean the floor’s surface with an anti-grease soap to remove any dirt and oil spots.

Laying Plastic Underlayment

• The plastic used for underlayment generally comes on rolls. To cut the underlayment to size, roll the plastic out across the floor and cut a strip that reaches from wall to wall. Secure the first strip of underlayment to the floor next to the wall with plastic tape. Cut another wall-to-wall strip of plastic and lay the strip so it overlaps the first strip by approximately 6 inches, securing the second strip to the first with the plastic tape. Continue across the floor this way until you reach the opposite wall.

Secondary Underlayment

• Before installing a walking floor over a cement subfloor, you may place a secondary underlayment over the floor’s surface. Most flooring materials, including hardwood and carpet, benefit from a foam, rubber or cork underlayment. Foam, rubber or cork all provide cushioning to the subfloor surface, which makes the floor feel softer, and reduces the noise when the floor is stepped on. Foam, rubber and cork underlayment also insulate the floor.

Laying Flooring

• When you install both a plastic and foam underlay on a cement floor surface, you get the same benefits as installing a combination underlay. Nearly any type of flooring may be installed over the cement floor once the underlays are in place, including hardwood or laminate planks and carpeting. You should not use foam beneath tile. If you want to install tiles, use backerboard or plywood underlay.