Material and rating
Porcelain (preferred): 8–12mm thick, dense, low water absorption (<0.5%), high impact resistance, suitable for floor + wall. Ceramic: 6–10mm, less dense, higher absorption, wall-only typically. Stone (marble, limestone, travertine): natural beauty but porous — requires sealing every 2–4 years, etches with acids (lemon juice, vinegar) — high-maintenance for daily-use bathroom; better in low-traffic powder rooms. Slip rating: R9 unsuitable for bathroom floor (kitchen-only); R10 minimum dry-area floor; R11 wet-area floor + shower. R12+ for outdoor pool decks (not relevant indoor). Verify R rating on supplier datasheet — many tiles labelled 'bathroom-suitable' are R9 only.
Format and pattern
Large format (600×600mm, 600×1,200mm, 1,200×1,200mm): fewer grout lines, modern look, hide minor floor flatness issues less well (require <3mm flatness over 2m). Medium (300×600mm, 600×300mm): traditional brick-bond layout, achievable on less-flat substrates. Small (mosaic 50×50mm, 100×100mm): used for shower floor (drainage gradient + texture grip) or accent feature. Pattern: brick bond (50% offset) classic; stack bond (aligned grid) contemporary; herringbone trending 2024–2026 (premium look, more cutting waste). Wood-effect porcelain plank (200×1,200mm) extends timber look without water risk.
Install and grout
Substrate prep: floor self-levelling compound to <3mm/2m flatness; walls 12mm cement backer board or plasterboard with waterproof primer (PVA only acceptable for dry zones, not wet). Adhesive: rapid-set flexible (S1 classification) for floors; standard flexible for walls; ensure full-bed (no voids — tap test before grouting). Grout: epoxy (Mapei Kerapoxy, Ardex EG15) in wet zones — non-porous, doesn't discolour, harder to apply but lifetime finish; cement-based (Mapei Ultracolor Plus) elsewhere — cheaper, easier, but yellows over time. Grout joint: 2mm minimum (porcelain), 3mm (ceramic) — accommodates dimensional variation. Calibrated batches: verify all boxes from same batch (lot number on label) — tiles vary 0.5–1mm between batches creating visible step in installation.
