Your tile contractor/tile setter's final work will look according to the tiles you choose. Tiles come from different materials. Uniquely, natural stones like marble are cut with a diamond saw and polished with a diamond planer; those tiles can be very close to perfect in shape and size, allowing your tile contractor to have smaller grout lines throughout the project.
Other tiles baked in the sun from softer materials, like Saltillo (red clay) tiles, are so uneven that your tile contractor must allow 5/8" grout lines to compensate for the variability.
Grout selection is determined by the width of the grout joints:
- Unsanded Grout: Used for grout joints less than 1/8" wide. The absence of sand prevents scratching on delicate surfaces like polished marble.
- Sanded Grout: Used for joints 1/8" wide or larger. The sand provides structure and prevents shrinkage and cracking as the grout cures.
- Quarry Grout: Used for joints wider than 1/4". It contains a coarser aggregate mixed with cement, ideal for thick joints in quarry tiles or Saltillo pavers.
Choosing the proper grout ensures color consistency and structural durability.
During manufacturing, tiles can be finished in two ways:
Pressed Edge (Cushion Edge): The surface edge has a curved, rounded taper caused by the mold press. Pressed edge tiles require wider grout joints to absorb the roundness and thickness variance.
Rectified Edge (Sharp Edge): Porcelain and ceramic tiles are baked first and then put through a precise diamond grinding machine. They are cut to near exact measurements with near-perfect straight 90-degree edges. Rectified tiles allow for extremely narrow grout lines (as tight as 1/16") and a flat, modern, seamless look.
Building your substrates (the wall or floor behind the tiles) is critical. The tile industry limits the deflection of wood-framed floors receiving tile to 1/360 of the span under load. This amounts to approximately 1/2 inch of allowable deflection for a 15-foot span.
Limiting deflection prevents tiles from popping and grout joints from cracking. While concrete floors move very little, plywood floor substrates must be rigid. The industry standard recommends a minimum of 1 1/8 inches of total plywood thickness over structural joists. A good subfloor needs to be durable, level, and free of residue.
For wet areas like bathrooms and showers, gypsum board (drywall) is not water-resistant. A professional tile setter will install cement backer boards and a premium waterproofing membrane (like Schluter®-KERDI or liquid-applied elastomeric membranes) so the installation can be guaranteed leak-free for a lifetime.
Additionally, electric floor heating systems (like Schluter®-DITRA-HEAT) can be weaved into uncoupling membranes before tiling. This adds comfort underfoot and helps accelerate evaporation in showers, preventing mold and keeping the area dry.
Your tile contractor will offer two methods to prepare floors:
- Mortar Bed (Mud Bed): A traditional method where a thick sand-and-cement mortar bed is floated over the subfloor. It allows the tile setter to build custom slopes (critical for drains) and flat surfaces in a single step.
- Self-Leveling Underlayment: A two-step process where a highly fluid, cementitious compound is poured over the substrate to level the floor automatically before thin-set application. Highly effective for flat, large format tile layouts.
Consult Andre
Have specific questions about your layout, substrates, or tile selection? We are here to help.
Email Andre directly at:
Request Estimate
Rectified edges vs. pressed edges require different grout sizes.
Custom tiled shower using custom mud bed and waterproofing.