Subfloor Preparation

SPC is rigid, so it bridges small bumps, but it will not bridge a dip. Most install problems start here.

Check flatness

Lay a straight 10-foot board or level across the floor in several directions. Gaps bigger than 3/16″ need filling; bumps need grinding or sanding down.

Concrete and basements

• Lay a 6 mil polyethylene vapor barrier, overlapping seams 8″ and taping them.
• Fill cracks and low spots with a cement-based patch.
• SPC will not be damaged by water, but trapped moisture under it can cause mold, so fix any active leak first.

Plywood and OSB

Screw down loose or squeaky panels and sand any raised seams. No vapor barrier needed on a wood subfloor over a heated space.

Over existing floors

You can float over sheet vinyl, well-bonded ceramic tile (fill grout lines wider than 1/4″) and hardwood. Remove carpet and carpet pad every time.