Preparation of the Subfloor for a Carpet

Wood Subfloors

• Many homes have plywood subfloors. Before laying carpet on these surfaces, sweep all dirt and debris from the floor. Check the floor for loose nails. Hammer and countersink the nails for a smooth surface. Walk the floor and listen for squeaks. Screw or nail down any loose boards to the floor joists at 6-inch intervals.

Concrete Subfloors

• Before laying carpet on a concrete subfloor, fill any cracks or holes with concrete patch. Concrete floors are porous and can absorb excess moisture that can ruin your carpet without proper preparation. Some concrete slabs have a vapor barrier installed beneath the slab. If yours does not, install one on top of the slab to protect your carpet and prevent the occurrence of mold and mildew. Position a layer of plastic sheeting on the floor, taping all the seams. Other options that provide a moisture barrier include a polyethylene shield with a dimpled surface that creates an air space and moisture barrier. A plywood subfloor is then installed over the barrier.

Leveling

• Whether you are installing carpet over a plywood or concrete subfloor, level any low areas or humps in the surface. For wood surfaces, fill low areas with floor patch. Scrape the surface with a straightedge to create a flat surface. Sand down surface humps with a hand or orbital sander. For concrete floors, use cementitious leveling compound to fill in low areas. Use a concrete grinder to grind down humps in the floor.

Pet Odors

• If your subfloor has been the victim of pet urine, you need to eliminate the odor before installing new carpet. If left untreated, the odor will permeate the new carpet. Paint the stained areas with a stain and odor blocker. Painting over the stains with these primers seals in the odors, giving you a fresh surface for laying your new carpet. After painting the surface with the primer, let it dry completely before beginning carpet installation.