New flooring telegraphs every bump, dip, and squeak underneath. Laminate clicks together and bridges small gaps — but large low spots flex and crack boards. Tile needs a flat plane or edges crack. Carpet hides minor issues but pad over humps wears faster.
Budget time for prep. It is often half the job on older homes.
Prep checklist
Remove all old flooring, staples, and adhesive lumps
Walk the floor — screw down loose OSB or plywood (squeak screws)
Check moisture: concrete should pass a plastic-sheet or meter test for laminate/tile
Grind or sand high spots; fill low spots with leveling compound
Vacuum thoroughly — grit under underlayment wears grooves in laminate back
For tile on plywood: verify deflection and use appropriate backer board
Concrete vs plywood
Concrete: patch cracks, grind paint or sealer if bonding tile mortar, install vapor barrier or moisture-rated underlay if manufacturer requires it for laminate.
Plywood subfloor: renail or screw on a grid pattern. Joints should not flex. Use underlayment or backer board per product specs — never float laminate directly on bare plank gaps without underlay.
Frequently asked questions
How flat does a subfloor need to be?
Many laminate specs allow 3/16 inch variation over 10 feet. Tile often needs 1/8 inch over 10 feet for large format. Use a long straightedge and feeler gauge — do not guess by eye.
Can I install over existing vinyl or tile?
Only if the old floor is fully bonded, one layer, and not cushioned vinyl. Laminate over soft vinyl flexes and fails. When unsure, remove down to subfloor.
Flooring Box Calculator provides estimates for planning only — not professional flooring installation advice. Verify quantities and products with your retailer. Read disclaimer