Tile a Bathroom Niche With Bert and May Encaustic Tiles in 8 Steps

Bert and May encaustic cement tiles are made with pigment running about 3mm to 5mm into a porous cement body. That cement draws in water, adhesive moisture, and grout pigment until a penetrating sealer is applied. The tiles are supplied unsealed, usually as nominal 200mm squares, and a batch can vary by roughly 1mm to 2mm along an edge. A dry layout is worth doing before any adhesive reaches the wall.

Seal the tiles before fixing

The damaging sequence is to install encaustic tiles raw and seal them only after grouting. Grey or white tile adhesive can be absorbed through the face and sides of cement tile, leaving a haze that does not lift with cleaning.

Apply a penetrating sealer to each tile before installation, covering the face and all edges. Bert and May refer to a tile and stone sealer. Lithofin MN Stain-Stop and Fila MP90 are common equivalents, soaking into the cement without leaving a surface film.

Set the tiles face up on a clean board. Brush or roll the sealer over the whole face, leave it for the dwell time printed on the tin, usually 5 to 15 minutes, then wipe away liquid that has not absorbed. Pooled sealer dries as shiny patches.

Two coats are typical for cement tile, with a couple of hours between applications. Do not treat the edges as an afterthought inside a shower niche. The cut sides around the niche perimeter are exposed to spray, so they need the same protection as the patterned face.

After grouting and curing, seal the finished niche again. The first sealer stage keeps adhesive and grout pigment out of the cement during installation. The later coat protects the tile faces and grout joints during everyday water exposure. Missing the first stage is the mistake that appears later as a grey cast across the pattern.

Build the niche as a waterproof box

A shower niche has five wet surfaces: the back, two sides, the top, and the shelf. Plain plasterboard fails quickly in that position. Use a cement-based or foam tile backer board such as Marmox or Wedi, or use tanked plasterboard finished with a liquid waterproofing membrane.

A prefabricated foam niche normally has a bonded flange forming a continuous waterproof shell. Tape the joints with the manufacturer sealing tape and bed them with the matching sealant.

For a niche made from backer board, run waterproof tape into every internal corner. Roll two coats of liquid membrane, for example Mapei Mapelastic or BAL WP1, over the whole interior and lap it at least 100mm onto the surrounding wall. Each coat has to dry to the colour change specified by the product before the next coat goes on.

Build a slight fall into the niche shelf or back surface before tiling, around 1 to 2 degrees forward. Water that reaches the shelf then drains out instead of sitting against grout lines. Trying to create that fall with adhesive thickness leaves a hollow beneath the tile, and that hollow can crack under a shampoo bottle.

Prime the cured membrane only when its data sheet requires a primer below the tile adhesive. Many current liquid membranes take a cement adhesive directly once they have cured.

Dry-lay the pattern and mark the centre

Encaustic patterns read across several tiles, so an awkward half-motif in a corner draws attention. Lay out the full group of niche tiles on the floor in the same orientation they will have on the wall, including the side returns. Bert and May patterns such as the geometric Vyne and the encaustic florals need the repeat centred on the back panel.

Measure the width of the niche back and mark a vertical centreline. A symmetric four-tile motif usually looks right with a grout joint on that line. For a single-tile motif, place the centre of a tile on the centreline. Whichever arrangement you choose, make the cuts at both edges equal, avoiding a full tile at one side and a narrow sliver at the other.

Number the back of each tile in pencil from the dry layout. Because the batch can vary by 1mm to 2mm, the joints may need small nudges as the tiles are set. Numbering keeps the repeat in order while those adjustments happen.

Spread adhesive, back-butter, and set the tile

A 200mm cement tile is heavy on a vertical face and can creep before the adhesive grabs. Use a white, fast-setting, deformable cement adhesive rated S1, such as Mapei Keraflex Maxi S1 or BAL Max Flex. White adhesive is important on pale cement tile, where grey adhesive can shadow through.

Comb adhesive onto the niche back with a 6mm notched trowel. Flatten the ridges so air voids are not left behind the tile. Add a thin, even back-butter coat to each tile as it is set. In a wet area, close to full coverage helps stop water tracking behind the tile and weakening the bond.

Set the lowest row first. Support it on a temporary ledger batten screwed level at the niche floor line, which keeps the row from sliding while the adhesive cures.

Use 1.5mm or 2mm spacers. Check each tile against its neighbour with a short spirit level and judge the finished face, since encaustic tiles often have a slightly cushioned edge. A perfect-looking joint width is less useful than a flush surface.

Wipe adhesive from the tile face immediately with a barely damp sponge. Even on sealed cement, cured adhesive can leave a mark.

Install the side returns after the back panel. They can be mitred or butted according to whether the pattern turns around the corner or ends at a trim. A mitred cement edge is fragile. Slim aluminium or brass tile trim protects that edge and usually gives a cleaner line.

Cut cement tile with a wet saw

A glaze-free cement face chips easily when forced through a cheap manual cutter. Use a wet saw with a continuous-rim diamond blade, feed the tile slowly, and support the offcut so it does not snap at the end of the pass.

Choose grout, clean in stages, and keep corners flexible

Grout colour changes how the niche pattern reads. A pale grey grout such as Mapei Ultracolor Plus 110 Manhattan keeps the lines quiet. A darker grout outlines each tile and can make a soft floral look like a graphic grid. Test a small batch against a spare sealed tile before choosing, since the dry colour is different from the wet swatch printed on the bag.

Mix a cement-based grout to a stiff consistency, not a runny one. Work it into the joints with a rubber float held at an angle. Because the face has already been sealed, grout releases from the surface more easily than it would from raw cement, though cleaning still needs several passes.

First wipe with a damp sponge, rinsing it often. Return when a light haze forms and wipe again. Once the joints have firmed up, polish the surface with a dry cloth.

Keep grout out of the internal niche corners, where movement occurs. The inside corners and the joint between the niche and the surrounding wall need colour-matched silicone so the junction can flex without cracking. Tool the silicone with a wet finger or a profiling tool for a neat concave line.

Leave the grout to cure for the time on the bag, commonly 24 to 48 hours, before applying the final sealer coat. Grouting over uncured membrane, or sealing while grout is still damp, traps moisture. That moisture can later show as efflorescence, the white powdery salts that rise through cement joints.

Seal again and delay the first shower

Reapply penetrating sealer across the finished niche once the grout has cured fully, covering tile faces and grout joints together. This coat does the daily work against shower water, and two thin applications dry more evenly than one heavy flood.

Wait for the full cure window before running water over the niche. Adhesive, membrane, and grout commonly need several days together to reach strength. A niche tiled over a weekend and used the next morning may look complete on the surface. The awkward part is that the surface can look finished while the layers underneath are still curing.