Padding for Under Laminate & Over Concrete Flooring

Preparing the Concrete

• Before you lay the padding, or underlayment, you must prepare the concrete floor. The floor must be level and have no cracks. Typically, the high and low spots on the concrete cannot be more than 3/16 inch in a 6-foot area. Use a straightedge or a level to determine where the floor is uneven. If you have areas of the floor that are not level or are cracked, you need to use a concrete compound such as latex- or acrylic-fortified cement-based patching material to fill in cracks and make floors level. Some manufacturers may recommend using layers of felt for correcting high and low spots, but you must check with the manufacturer or the warranty before using felt.

Moisture Test

• Perform a moisture test on the concrete floor. Your local flooring dealers can perform the moisture test or recommend a retailer where you can purchase a test kit. The test will tell you how much moisture radiates through the concrete. For concrete floors, the acceptable reading is 4.5 percent. Perform this test for basement floors or any concrete floors over crawlspaces.

Padding

• The padding for laminate floors is made of different materials. If the laminate doesn’t come with the moisture barrier underlayment already attached to the laminate planks, you will need purchase the underlayment separately. The recommended underlayment will vary between manufacturers of laminate flooring, but the minimum is 6-mil polyethylene film.

Padding Installation

• The underlayment is rolled out so the ends are up against the wall. When you have seams, the underlayment must have an overlap of 8 inches at the seams so that moisture cannot get through.