Procedures for installing floor tiles

(1) Substrate preparation: Clear debris from the substrate; use a chisel to remove mortar residue and droppings, ensuring the surface is scraped clean of any mortar crusts.

(2) Cement mortar leveling layer.
1) Setting screed strips (guides): Dampen the cleaned substrate with water. Measure down from the elevation control line to the top surface of the leveling layer, then set horizontal reference points (mortar pads) to establish the height (the top of these pads corresponds to the underside of the floor tile bonding layer). Install screed strips around the perimeter of the room and intermediate strips at intervals of approximately 1.5 meters. For rooms requiring drainage slopes, set the strips to the specified gradient, radiating towards the floor drain.
2) Applying the leveling layer: After setting the screed strips, promptly remove any excess mortar used for the strips. Spread 1:3 cement mortar between the strips (minimum thickness of 20 mm). Spread the mortar evenly with a flat shovel and level it with a straightedge. Compact and smooth the surface with a wooden float while verifying the elevation and drainage slope; subsequently, perform water curing.

(3) Setting out cross-control lines and elevation lines: Once the leveling layer reaches a strength of 1.2 MPa, mark the elevation line for the top of the finished floor surface on the surrounding walls and columns, based on the +50 cm or +100 cm wall control lines and the design elevation. Snap cross-control lines and grid lines onto the substrate floor according to the tile layout plan and specified joint widths. If the design includes specific patterns, snap positioning lines for the patterns, mark them clearly, and conduct a preliminary check to prevent errors.

(4) Tile layout and trial laying: Arrange the tiles symmetrically perpendicular to the doorway. If the trial layout results in a cut tile (less than a full tile) at the end of a row, split the difference between that cut tile and a full tile to create two larger cut pieces, placing them symmetrically on both sides. Regarding the direction parallel to the doorway: when a full tile is placed at the doorway, the innermost tile should ideally be larger than half a tile (or exceed 200 mm). If this requirement cannot be met, the dimensions of the innermost cut tile and the full tile at the doorway should be combined and divided equally between the two locations. For tight-joint installation, the joint width must not exceed 1 mm; a trial layout based on construction detail drawings is required, and formal installation should proceed only after the trial layout is verified as correct.

(5) Tile laying. Evenly sprinkle water on the cleaned floor surface, then use a broom to evenly apply a neat cement slurry (water-cement ratio of 0.4–0.5). The application area should not be too large; the process must be closely coordinated with the next step, applying the cement mortar bedding layer immediately after the slurry. The bedding layer consists of semi-dry cement mortar mixed at a 1:2.5 ratio (cement:sand); the mortar should be used immediately after mixing and before initial set to ensure bonding quality. Level the mortar with a wooden float as it is laid. When laying tiles, apply bonding mortar (1:2 ratio) to the back of the tile and place it onto the prepared semi-dry mortar bed. Position the tile so its top edge is slightly above the finished floor level line; after aligning and squaring the tile, place a wooden board over it and tap it firm with a rubber mallet. Proceed with installation by backing out from the inner area toward the exit, ensuring the mortar bed is fully filled and the tiles are tightly and solidly joined. At floor drain locations, cut the tiles with a grinding saw to fit the drain precisely. Ideally, tile an entire room in one session; for large-scale projects, use a phased or sectional installation approach.
To establish correct positioning and elevation, first lay 2–3 rows of tiles longitudinally starting from the doorway; use these as reference lines to set longitudinal and transverse level lines. Work from the inside out, ensuring no one steps on the freshly laid tiles, and align each tile with the reference lines.

(6) Curing. Begin watering for curing within 24 hours of tile installation. In hot summer weather, commence watering and covering 12 hours after installation; the curing period must be at least 7 days.

(7) Installation of skirting boards. When plastering the wall, leave the area designated for the skirting board unplastered to prevent the skirting from protruding excessively from the wall surface. Before installation, soak the tiles in water and let them air-dry until the surface moisture evaporates, while also wetting the wall surface. During installation, set one tile at each inner corner at the ends of the wall, then stretch a guide line to ensure the top edge of the skirting tiles is straight and the projection thickness is consistent. Apply bonding mortar (1:2 cement mortar mixed with a bonding agent according to the manufacturer's instructions) to the back of the tile, ensuring full coverage; press the tile firmly onto the wall immediately, aligning the top edge with the guide line. Promptly scrape away any squeezed-out mortar and clean the tile surface. Unless otherwise specified in the design, the skirting tile joints should align with the floor tile joints or follow a staggered (running bond) pattern.

(8) Joint grouting. Perform grouting once the mortar strength of the tile layer reaches 1.2 MPa (typically 36 hours in summer and 60 hours in winter). Use a cement paste or 1:1 cement mortar-mixed with cement (or white cement) and mineral pigments to match the design color-that is of the same type and strength grade as the mortar used for the tile bed. Ensure the grout joints are distinct, straight, smooth, and uniform in depth and color, with the grout surface recessed 0.5–1.0 mm below the tile surface.
Regarding seasonal construction: in principle, floor tile installation should not be performed when the ambient temperature is below 5°C in winter. If construction is unavoidable, seal exterior doors and windows to provide thermal insulation and ensure work proceeds at temperatures above freezing. Additionally, add an antifreeze agent to the mortar based on temperature conditions (dosage according to the product instructions) and provide thermal covering to ensure the quality of the floor tile installation.