Tile, Grout and Thinset: What Does Each Material Do?
Three different materials with three different jobs in a tile installation
Tile — the visible surface
Tile is the finished wear surface, sold by the box covering a fixed area. Quantity is calculated from room area plus a cut-waste allowance that depends heavily on the layout pattern, as covered in BuildFactor's tile and flooring guide.
Thinset — the bonding layer
Thinset mortar bonds the tile to the substrate underneath it. Its quantity depends on the tile size and the trowel notch size used to spread it — a larger tile generally needs a larger notch (and therefore more thinset per square foot) to ensure full, even contact and support across its larger surface.
Grout — filling the joints
Grout fills the gaps between tiles, and its quantity depends on tile size, grout joint width, and grout depth (roughly the tile's thickness) — smaller tiles with wider grout joints use noticeably more grout per square foot than large tiles with narrow joints, since there's proportionally more joint length per unit of area.
Why they're calculated separately
Each material's quantity depends on different variables — tile on area and layout waste, thinset on tile size and notch, grout on tile size and joint width — so combining them into a single 'flooring material' estimate would obscure the actual drivers and make it harder to adjust for a specific installation's details.