How to Prepare Bathroom Walls for Tile: A Practical Guide for Homeowners

1. What a Wall Needs to Be Tile-Ready

Before any tile touches the wall, your surface must meet several key conditions:

1.1 Proper Geometry

First, check the wall’s measurements. Use a tape measure to determine the height and width of each wall you plan to tile. Create a simple layout plan on graph paper, including windows, doors, and plumbing cutouts.

Next, check the wall’s squareness. Measure the diagonals—if they are equal, your wall corners are square. Use a level and a framing square to make sure vertical and horizontal surfaces are straight and at 90° angles. Mark any spots that need attention.

1.2 Solid and Stable Surface

A firm, solid base ensures the tile stays in place over time. Any cracks, chips, or bulges should be fixed before tiling:

• Remove all old materials like paint, plaster, or tile.

• Fill cracks with patching compound or cement mix.

• Knock down any bulges using a hammer and chisel.

• Brush off dust using a stiff wire brush.

1.3 Adhesion (Adhesive Compatibility)

For your tile to bond correctly to the wall, the surface must allow good adhesion:

• Use tile glue designed for the specific material (cement board, drywall, etc.).

• If reusing older tile or painted surfaces, roughen them with a sander to improve bonding.

• Apply a primer (bonding agent) to enhance stickiness.

• Make sure the tiles have a textured backside or ribbing for better grip.

Pro Tip: Check the adhesive’s strength on the label—it’s measured in MPa. A rating of 1 MPa means it can hold about 10 kg (22 lbs) per cm².

2. Removing Old Wall Coverings

If your bathroom already has paint, plaster, or tile on the walls, you’ll need to strip it off before starting fresh. Even if tile manufacturers claim you can tile over old paint or tile, it’s always safer to start clean.

2.1 Removing Paint

Use one of these methods:

• Scrape off peeling paint with a putty knife.

• Use a heat gun to soften paint, then scrape it away.

• Apply paint remover and wait for bubbling, then scrape.

• Use a grinder with a wire brush for stubborn areas.

If some paint won’t come off, you can score it with a utility knife to give adhesive something to grip.

2.2 Removing Old Tile

Here’s how to remove old tile from your bathroom walls:

• Protect your fixtures before starting.

• Use a hammer and chisel to pop off tiles one by one.

• A rotary hammer with a chisel bit makes the process faster.

• Start from the top row and work your way down.

• After tile removal, patch any holes or damaged areas.

Note: If tile is stuck on drywall (like green board), chances are you’ll have to remove the drywall as well and replace it.

3. Wall Leveling

Even slight unevenness can make your tile job look crooked. Here’s how to flatten those bathroom walls.

3.1 Plastering

This is the traditional “wet” method:

1. Use a plumb line or level to mark where walls are uneven.

2. Knock down high spots with a chisel or angle grinder.

3. Use a straight edge and screws or nails to set up vertical “guide rails” (called screeds or beacons).

4. Apply bonding primer.

5. Throw on the first layer of plaster (up to 10 mm thick), using a trowel.

6. Smooth it out by running a screed board along your guide rails.

7. Let it dry fully—usually 24 hours—then apply a second coat if needed.

Don’t forget to sand and prime the surface after plastering to ensure a perfect tile grip.

3.2 Using Greenboard or Cement Board (Drywall Leveling)

Many American DIYers prefer the “dry” method—installing tile-ready boards instead of plastering.

• Use mold-resistant drywall (greenboard) or cement board for bathrooms.

• Mount galvanized steel tracks to the floor and ceiling.

• Insert vertical studs every 16 inches, checking alignment with a level.

• Add horizontal braces to reinforce the frame.

• Screw in your drywall sheets.

• Tape and mud the seams.

• Apply waterproof primer over the entire surface.

Drywall saves time, keeps things cleaner, and allows you to hide pipes or wires behind the wall.

4. Plumbing Prep: Water Outlets and Fixtures

Don’t forget the plumbing! Before tiling, mark and prep the areas for:

• Sink faucet and valve connections.

• Shower or tub valves.

• Bidet spray hookups.

• Heated towel racks.

• Radiator or floor heating pipes.

• Water heater inlets and outlets.

It’s best to install all plumbing hardware before you tile so you can make precision cuts for them in the tile.

5. Waterproofing (A Must for American Bathrooms)

Bathrooms deal with constant moisture—and drywall alone won’t cut it. Proper waterproofing is a must.

Where to Waterproof:

• The entire shower wall area.

• Wall sections that connect to the bathtub or sink.

• Around water outlets.

• Bathroom floor (especially if tiling directly on slab).

How to Do It:

1. Clean and dry the surface.

2. Apply a bonding primer.

3. Use a waterproofing membrane or liquid rubber sealant (like RedGard).

4. Roll or brush on the first coat and let it dry fully.

5. Apply a second coat in the opposite direction (vertical vs. horizontal strokes).

Pay extra attention to corners and joints—they’re most prone to leakage.

Final Thoughts

A great tile job doesn’t start with the tile—it starts with perfect preparation. Cleaning, flattening, and waterproofing your bathroom walls ensures that once the tile goes up, it stays up—for years. Whether you're using classic plaster or modern greenboard, the time and effort you put into prep will directly affect the result. Happy tiling!