LVP over a slab - what prep do I need?

Flatness first

If the slab is not flat, the floor flexes, the locking joints work loose and you get gapping and failed edges. Grind the high spots, fill the low ones with a self-levelling compound, and check with a long straightedge rather than by eye. This is the step that gets skipped when a price looks too good.

Then moisture, which is the Florida part

Slabs on grade here often have a marginal vapour barrier underneath, or none. Do a calcium chloride or relative humidity test rather than assuming, and choose an underlayment or membrane rated for the reading you get. Moisture is what fails these floors in this state, not wear.

Installation details that matter

• Leave the expansion gap the manufacturer specifies at every wall and every vertical, including under door jambs.
• Do not trap a floating floor under cabinets or a heavy island.
• Use transition strips at doorways on long runs rather than running one continuous field.
• Acclimate the boxes in the room they are going into, for as long as the manufacturer says.

Before you buy the material

1. 1Test the slab for moisture and get the number in writing.
2. 2Check the product warranty against that number.
3. 3Confirm who is doing the floor preparation and whether it is in the price.
4. 4Agree what happens if the slab needs more levelling than expected.

If the floor you are replacing was tile that cracked, find out why before you cover it: why floor tiles crack and pop. For rentals, LVP is usually the right answer for a different reason: what is worth replacing between tenants.

Glue-down or floating

Floating is faster, more forgiving of a slightly uneven slab and easier to repair, but it moves, so it needs the expansion gaps and it can sound hollow underfoot. Glue-down feels more solid, tolerates temperature swings better in a sun room or a lanai conversion, and is much harder to lift later.

In most Central Florida houses floating is the right default. Rooms with large glazing, direct sun or a history of moisture are where glue-down earns its extra cost.

Transitions and skirting

Two details make a floating floor look installed rather than laid: the gap at every wall hidden behind the skirting or a scotia, and a proper threshold where the floor meets tile or carpet.

Ask how door jambs are handled as well. Undercutting them so the flooring runs beneath is the finished way; cutting the plank around them is the quick way, and it shows.