Tiling & Stone
QA inspection checklist

Substrate

1. 1.

   Substrate flat and primed
   What to look forSubstrate (plaster, blockwork, screed, tile backer board) flat under 2 m straight edge. Suction primer applied to dusty/absorbent surfaces. Mechanical key for shiny surfaces. Substrate fully cured (typically 6+ weeks for new render/screed).
   Acceptable whenPer BS 5385-1 to 5: substrate flatness ±3 mm in 2 m straight edge for thin-bed adhesive; ±6 mm in 2 m for thick-bed. New render cured 14+ days, screed 6+ weeks before tiling. Primer per adhesive manufacturer's data sheet.
   StandardBS 5385-1:2018 — Wall and floor tiling — Ceramic, natural stone, terrazzo. BS 5385-3:2014 — Internal floor tiling. BS 5385-4 — Tiling in special conditions. TTA Manual.
   Common defectsTiles laid on uncured render — debonding within 6 monthsNo primer applied to dusty plaster — adhesive starves of moistureSubstrate not flat — > 6 mm in 2 m, lippage inevitablePlasterboard direct without tile backer in shower area — degradesSmooth render without mechanical key — adhesive slip
2. 2.

   Tanking applied to wet areas
   What to look forTanking membrane (liquid-applied or sheet) covers floor of wet area, walls of shower zone to height of shower head + 200 mm. Continuous through all corners, around penetrations, lapped at joints. Pre-formed corner pieces and pipe collars used.
   Acceptable whenPer BS 5385-4 / NHBC: tanking to manufacturer's spec, AGREMENT/BBA certified. Wall tanking up to 1800 mm minimum or shower head + 200 mm. Continuous through corners with reinforcement strip. Pipe collars over all penetrations.
   StandardBS 5385-4:2015 — Tiling in special conditions. NHBC Standards 8.2. BBA / Agrément certificates for membranes.
   Common defectsTanking only on shower wall, not floor — water tracks under trayNo reinforcement strip at internal corners — splits with movementPipe collars omitted — sealant only used, failsTwo-part liquid tanking under-mixed — patchy cureTanking over silicone (incompatible) — debonds

Tile Installation

1. 3.

   Tile type and colour match spec
   What to look forTile model, dimension, colour, shade reference, surface finish (matt, polished, structured) match approved sample. Slip rating (R-class for floors) per spec — R10 minimum for general, R11/R12 for wet floors. Same shade batch ("calibre") across area.
   Acceptable whenTiles to BS EN 14411 — porcelain group BIa absorption ≤ 0.5%, ceramic group BIIa 0.5-3%. Slip resistance to DIN 51130 (R-class) or PTV ≥ 36 wet. Same shade and calibre within visual area.
   StandardBS EN 14411:2016 — Ceramic tiles. BS 5385 series. BS 7976-2 (slip). DIN 51130 (R-class).
   Common defectsMixed batch numbers — visible shade variation, "patchwork" effectCalibre mismatch — tiles slightly different size, joint grows or shrinks across areaR10 used in wet area where R11/R12 needed — slip claim riskGlazed (BII) tile used externally where porcelain (BIa) needed — frost crackingHoned/polished tiles in wet bathroom floor — slip hazard
2. 4.

   Tiles level — lippage within tolerance

   Record: Lippage (mm)
   What to look forLippage (vertical step at joint) within tolerance — feel with hand and check with straight edge. Diagonal sighting along walls picks up worst lippage. Levelling clip system in use on rectified large-format tiles.
   Acceptable whenPer BS 5385: lippage ≤ 1 mm for tiles up to 200 mm; ≤ 2 mm for larger tiles. For rectified large-format porcelain (≥ 600 mm), tighter — typically 1.5 mm max with levelling system. Floor flatness SR2 (±5 mm in 3 m) acceptable.
   StandardBS 5385-1, BS 5385-3. TTA Code of Practice. ISO 13007 (adhesives).
   Common defectsExcessive lippage > 2 mm — substrate not flat or adhesive not back-butteredLevelling clips not used on large-format tiles — tiles drop one sideCumulative joint drift — joints growing or shrinking across runLippage at edges/cuts where bedding inadequate
3. 5.

   Joints consistent

   Record: Joint width (mm)
   What to look forSpacers used during fixing. Joint width consistent across area — typically 2-3 mm for porcelain, 3-5 mm for ceramic, 5-10 mm for stone. Joints aligned (not staggered offset wrong way). No "running joint" creep.
   Acceptable whenJoint width per BS 5385 / TTA: minimum 2 mm for rectified porcelain, 3 mm for ceramic, 5 mm typical for stone. Tolerance ±0.5 mm. Joints straight in line with grid; offset patterns staggered as designed (50% or 33%, not random).
   StandardBS 5385 series. TTA Code of Practice.
   Common defectsVariable joint width across same wall — no spacers usedJoints < 1 mm — no allowance for thermal/moisture movementRandom offset on stagger pattern — looks chaoticCut tiles narrower than ½ at perimeter — visually unbalancedCumulative dimensional creep — at end of wall, last full tile is too wide
4. 6.

   Adhesive coverage > 95%
   What to look forTap test reveals no hollow spots. Lift sample tile during install — adhesive coverage on back evaluated visually. Notched trowel direction perpendicular to short edge of tile (combs squashed during pressing). Back-buttered for large format.
   Acceptable whenPer BS 5385: ≥ 80% solid bedding for internal walls (dry areas), ≥ 95% for floors and wet walls. External and large-format ≥ 100% (full bed, back-buttered). Adhesive class C2 (improved cementitious) typical, S1/S2 (deformable) for UFH/heated.
   StandardBS 5385 series. BS EN 12004:2017 — Adhesives for tiles. BS EN 12002:2008 (deformability).
   Common defectsHollow tiles tap test — combs not squashed, < 95% coverageNo back-buttering on large format — only ridges of adhesive contactingClass C1 used over UFH where S1/S2 deformable specifiedAdhesive skinned over before tile placed — bond failsNotch direction wrong — air channels trapped

Grouting & Finishing

1. 7.

   Grout joints full and consistent
   What to look forGrout fills joint to depth ≥ 2/3 of tile thickness. Tooled flush with tile face (or slightly below for textured tiles). No voids or pinholes. Grout fully cured before silicone applied. Colour consistent — mixed in single batch where possible.
   Acceptable whenPer BS 5385 / BS EN 13888: grout fills joint to within 1-2 mm of tile face. Cementitious CG2 standard, RG (epoxy reaction resin) for chemical/heavy duty. Joint depth fill ≥ 2/3 tile thickness.
   StandardBS EN 13888:2008 — Grouts for tiles. BS 5385 series. TTA Code of Practice.
   Common defectsPinholes/voids in grout — surface set before troweled in fullyJoint depth shallow — water enters and lifts grout outColour banding — multiple batches mixed differently (water content)Cement grout in chemical/food prep area where epoxy neededGrouting before adhesive cured — solvent vapour locks grout
2. 8.

   Silicone at movement joints and perimeter
   What to look forSilicone (sanitary grade with mould inhibitor) at all internal corners, perimeter (wall/floor, wall/ceiling), around baths, basins, shower trays. Backer rod where joint > 6 mm. Tooled smooth. No grout at these joints.
   Acceptable whenSanitary silicone to BS EN 15651-3 type S (sanitary). Joint depth ≥ ½ width, max width 12 mm. Backer rod for joints > 6 mm. Application per BS 6213.
   StandardBS 5385-4. BS EN 15651-3:2017 — Sealants for sanitary joints. BS 6213:2000 — Sealing joints in buildings.
   Common defectsGrout used at internal corners instead of silicone — cracks with thermal movementSanitary silicone without mould inhibitor — black mould within monthsSilicone tooled too thin — bond stress, splitsSilicone over wet substrate — fails to cureNo backer rod in deep joint — silicone three-sided adhesion, splits
3. 9.

   Tiles clean and free from residue
   What to look forTile surface clean, no grout haze. Polished/honed surfaces specifically — no acid residue or etching from acid wash. Inspect under raking light for hairline scratches. Sealant applied where required (natural stone, unglazed porcelain).
   Acceptable whenFinal clean per BS 5385 / TTA: tiles to be free from grout, adhesive, sealant residues. Acid clean (where used) neutralised with sodium bicarbonate. Penetrating sealer applied to absorbent stone (granite, limestone) per supplier.
   StandardBS 5385 series. TTA Code of Practice. Stone Federation guidance.
   Common defectsGrout haze visible under raking light — final buff missedAcid clean on marble/limestone — etching, no longer polishedStone unsealed — staining within first weeks of useCement residue not removed before grout curedDamage from follow-on trades — bath or shower screen scratches tiles

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