How do you prepare a floor for new tile?

Why prep matters more than the tile

Tile is hard and rigid. It doesn’t bend. If the floor under it flexes, dips or moves, the tile or the grout cracks. Most tile problems we get called about, cracked tiles, loose tiles, grout that keeps crumbling, trace back to the floor underneath, not the tile itself. So a good tile job is mostly a good prep job.

Step 1: Get down to a solid base

First, the old flooring comes out. Carpet, vinyl, laminate and old tile usually all have to go, along with staples, nails, old adhesive and anything loose. Tile over tile is sometimes possible, but only if the old tile is fully bonded and flat, and it raises the floor. In most cases, a clean start is the safer choice.

Some older sheet flooring and adhesives may contain asbestos. If your floor is old and you’re not sure, have it tested before it’s scraped or torn out.

Step 2: Check for bounce and soft spots

On a wood floor, we walk the whole room and look for spots that flex, squeak or feel soft. Common problem areas in Long Island houses:

• Around toilets, tubs and sinks, where slow leaks rot the subfloor
• Near exterior doors and sliders
• Floors over wide joist spans that bounce when you walk

Rotted subfloor gets cut out and replaced. Loose subfloor gets screwed down to the joists. If the whole floor is too bouncy, we may add a layer of plywood, or add blocking between the joists from below if we can reach them from a basement.

Step 3: Make it flat

Flat and level aren’t the same thing. A floor can slope slightly and still take tile. What it can’t have is humps and dips, especially with larger tiles. We check the floor with a long straightedge. High spots get sanded or ground down. Low spots get filled with a floor patch or a self-leveling compound, which is poured on and spreads out into a flat surface.

Step 4: Add the right layer on top

Over a wood subfloor

Tile shouldn’t go straight onto plywood. We install cement backer board, screwed down on a bed of thinset (the mortar used for tile), or an uncoupling membrane, a thin plastic sheet that lets the wood and tile move a little without cracking the tile. Both give the tile a stable surface.

Over concrete

Concrete basement floors and slab-on-grade rooms are good for tile, but concrete cracks. We look at existing cracks and use a crack isolation membrane over them so a crack in the slab doesn’t carry up through the tile. We also check for moisture coming up through the slab.

In a bathroom or shower

Floors that will get wet, especially walk-in showers, need waterproofing. That can be a liquid membrane that’s rolled on or a sheet membrane, applied and allowed to cure before tile. Shower floors also need a slope to the drain built in before tile.

Step 5: Clean and lay it out

Dust and debris keep thinset from bonding, so the floor gets swept and vacuumed. Then we plan the layout. We find the center of the room, dry-lay tiles to see where the cuts land, and adjust so you don’t end up with thin slivers at a doorway or along the most visible wall. We also plan how the tile meets other floors, so the transition is even.

A few things homeowners don’t think of

• Floor height. Backer board plus tile raises the floor. Doors may need trimming, and the transition to the next room may need a reducer.
• Toilet flange. The flange may need to be raised to match the new floor height so the toilet seals right.
• Baseboard. It usually comes off for the job and goes back on, or gets replaced, once the tile is in.
• Radiant heat. If you want a heated floor, it goes in during prep, not after.

How we handle it

We check the floor before we give you a price, so the prep is written into the itemized quote instead of added later. If we find damage once the old floor comes up, we show you before we fix it. Your written price includes a start date and how long the job will take.

See how we lay floors, showers and backsplashes on our tile installation page, or call 631-745-9982.