NCCER Tile cheat sheet

Personal protective equipment for tile work: safety glasses with side shields, nitrile or rubber gloves for thinset and grout, knee pads, and NIOSH-approved respiratory protection (N95 minimum; P100 or supplied air for silica-heavy dust) when cutting, grinding, or mixing.

Silica hazard: cutting tile, mixing cementitious powder, and dry sweeping generate respirable crystalline silica; wet cutting, dust extraction, and wet cleanup are the primary controls.

Wet saw electrical safety: plug into a GFCI-protected circuit, keep the water tray filled above the pump intake, and never reach into the blade path; unplug before changing blades or clearing jams.

Mortar and grout are alkaline (portland cement pH typically 12-13); prolonged skin contact causes cement dermatitis and chemical burns, so wash promptly and use barrier or nitrile gloves, not cotton.

Backer board and tile cutting tools: score-and-snap for drywall and cement backer board, snap cutter or wet saw for ceramic, and diamond blade or grinder with water or dust shroud for porcelain and stone.

Common tile types by water absorption: non-vitreous (>7%), semi-vitreous (3-7%), vitreous (0.5-3%), impervious (<0.5%); porcelain is generally impervious and requires modified thinset.

Material estimating: order 10% extra for straight-set field tile and 15-20% extra for diagonal, herringbone, or rooms with many cuts; keep one box for attic stock.

Jobsite housekeeping and lift technique: keep walkways clear of thinset droppings and offcuts, and lift mortar bags and tile boxes with legs, not the back; a bag of thinset is typically 50 lb.

Substrate flatness tolerance for thin-set tile per ANSI A108: maximum variation of 1/4 in. in 10 ft, with no more than 1/16 in. in 12 in.; correct with patching compound or grinding before layout.

Wood subfloor deflection for ceramic and porcelain: maximum L/360 of the span; for stone, L/720 and a minimum two-layer floor. Check joist size, spacing, and span against a deflection table.

Concrete slab acceptance: cure at least 28 days, be free of curing compounds, sealers, paint, and adhesive residue, and pass a moisture test (ASTM F2170 in-situ RH or ASTM F1869 calcium chloride) before covering.

Cement backer board installation: set in a bed of polymer-modified thinset, fasten with specified corrosion-resistant screws at the manufacturer's spacing (often 8 in. on center at edges, 8 in. in field), stagger joints, and tape and skim joints with thinset.

Waterproofing in wet areas: apply liquid or sheet membrane to walls in showers to at least 6 ft above the floor and 2 in. above the curb, with seams, corners, and penetrations reinforced with banding.

Crack isolation and uncoupling membranes: use ANSI A118.12 crack isolation where in-plane substrate cracks exist and A118.10 waterproof membranes where water intrusion must be stopped; neither corrects structural deflection.

Gypsum drywall is not an acceptable tile substrate in wet areas; in dry areas use it only with adhesives and tile weights approved by the manufacturer, and never in showers.

Substrate cleanup before setting: vacuum dust, scrape thinset ridges and paint overspray, and prime porous surfaces with the membrane or thinset manufacturer's recommended primer.

Thinset classification per ANSI A118.4 (modified, polymer-added) and A118.1 (unmodified); porcelain, glass, and stone generally require A118.4 or better, and large-format tile calls for A118.4 with non-sag or LHT (large and heavy tile) rating.

Latex or polymer modification improves bond strength, flexibility, and water resistance; never add liquid admix to a dry-set mortar that already contains polymer, and never add water beyond the bag ratio.

Mix ratio and pot life: follow the bag's water volume exactly, slake 5-10 minutes, remix, and use within the stated pot life (often 2-4 hours); discard mortar that has begun to set, never retemper with water.

Notch trowel selection: match notch depth to tile size and substrate flatness; typical starting points are 1/4 x 1/4 in. for tile under 12 in., 1/4 x 3/8 in. for 12-16 in., and 1/2 x 1/2 in. for large-format tile with back-buttering.

Coverage rule: aim for at least 80% mortar contact in dry areas and 95% in wet areas or exterior; check by lifting a freshly set tile and inspecting the back.

Back-buttering and keying in: flat-trowel thinset into the substrate to key it, then comb in one direction; back-butter large-format and stone tile to fill the back's profile.

Movement joints: provide 1/4 in. minimum expansion joints at perimeter walls, changes of plane, and every 20-25 ft in interior fields and 8-12 ft exterior, per TCNA EJ171; never grout these joints.

Lippage control: use a leveling clip or wedge system, keep mortar bed consistent, and stay within ANSI A108.02 lippage tolerance (1/32 in. for grout joints under 1/4 in., 1/16 in. for wider joints).

Layout sequence: establish square reference lines from the room's longest, most visible wall, center the layout on that wall, and check squareness with the 3-4-5 method or diagonal measurements before setting any tile.

Cuts and focal points: place full tiles at the most visible entry or focal wall and push cut tiles to less visible edges; avoid cuts narrower than half a tile by shifting the layout half a tile.

Grout joint width: use the manufacturer's minimum, typically 1/16 in. for rectified porcelain, 1/8 in. for standard ceramic, and 3/16 in. or wider for stone with dimensional variation; wider joints hide size variation.

Grout types: sanded for joints 1/8 in. and wider, unsanded for joints under 1/8 in. and for scratch-prone polished stone; epoxy grout for high chemical, stain, or cleanability demands.

Grouting procedure: wait for thinset cure per manufacturer (often 24 hours), work grout diagonally into joints with a rubber float, strike off excess, and clean with a damp sponge before haze sets.

Sealing: cementitious grout and natural stone are typically sealed after full cure (often 72 hours); silicone caulk, not grout, is used at changes of plane and at fixtures.

Final cleanup and punch list: remove grout haze with a manufacturer-approved haze remover, polish stone, re-caulk wet-area joints, and verify no lippage, hollow-sounding tile, or open joints remain.

Wet saw blade direction and cooling water keep the cut cool; a dry blade on a wet saw or a dry cut on porcelain overheats the blade and can shatter the tile.

Hearing protection is required when operating a wet saw or grinder for extended periods; noise levels commonly exceed 85 dBA.

Knee pads and a kneeler board reduce knee stress during floor setting; rotate tasks and take breaks from kneeling and overhead work.

Material handling: tile boxes are heavy and awkward; use a cart or two-person lift, and store boxes flat and out of traffic paths.

First aid: flush eyes at an eyewash station for 15 minutes after mortar or grout contact, and report cement burns promptly because they can be serious chemical burns.

Grinder safety: use a guard, a diamond cup or blade rated for the RPM, and a dust shroud or water feed; never remove the guard to fit a larger wheel.

Confined and wet-area work: use GFCI protection, keep cords out of standing water, and inspect cords for damage before each shift.

Waste handling: cured thinset and grout are construction debris; do not pour liquid mortar or grout down drains because it sets and clogs piping.

Moisture testing: ASTM F2170 in-situ relative humidity probes (install 24 hours before reading, read at 72 hours) and ASTM F1869 calcium chloride (72-hour test) are the standard methods; results are compared to the adhesive or membrane's limit.

Substrate flatness is measured with a 10 ft straightedge; high spots are ground down and low spots filled with patching compound, never with extra thinset at setting time.

Deflection formula check: L/360 means the allowable deflection is the span in inches divided by 360; a 12 ft (144 in.) span allows 0.4 in. of deflection.

Backer board joints must be staggered and must not align with subfloor panel joints; fasteners must be set flush, not countersunk through the board face.

Shower pan construction: preslope under the liner, liner lapped over the curb and up walls, weep holes at the drain kept clear, and a final mortar bed over the liner.

Exterior and wet-area substrates: use exterior-rated backer board or a waterproof membrane system, and slope horizontal surfaces to drain at 1/4 in. per foot minimum.

Subfloor panel thickness: follow the backer board manufacturer's minimum, commonly 5/8 in. exterior-glue plywood or OSB over joists at 16 in. on center, with a second layer for stone.

Adhesive residue, wax, and curing compounds must be removed by grinding or chemical stripper and the slab neutralized and vacuumed before any membrane or thinset is applied.

Large-format tile (one side 15 in. or greater) requires a large-and-heavy-tile (LHT) mortar meeting ANSI A118.4 or A118.15 and a trowel notch of at least 1/2 x 1/2 in. with back-buttering.

Glass tile: use a glass-tile-specific bright white modified thinset, avoid dark mortar that shows through, and allow longer cure before grouting.

Mosaic sheets: keep joints aligned with the field layout, use a grout float or beating block to embed the sheet evenly, and check sheet edges for lippage.

Cementitious grout mixing: follow water ratio, slake 5-10 minutes, remix, and use within pot life; too much water causes shrinkage, efflorescence, and weak joints.

Silicone caulk at movement joints: use 100% silicone or a manufacturer-approved sealant matched to the substrate, and tool the joint concave for a clean finish.

Membrane and adhesive compatibility: use the membrane manufacturer's approved thinset over the membrane; some membranes require unmodified thinset over them.

Curing before grout: allow thinset to cure per the bag (often 24 hours) and longer for large-format or dense porcelain; grouting too early traps moisture and weakens bond.

Storage: keep thinset and grout dry and off the slab; bagged cementitious products have a shelf life (often 1 year) and hardened lumps mean the bag should be discarded.

Layout math: to center a layout, measure the wall length, divide by the tile-plus-joint module, and split the remainder evenly at both ends; check both ends are equal before setting.

Diagonal layout: establish a 45-degree reference by measuring equal distances on two perpendicular lines, and verify with the 3-4-5 triangle before snapping the diagonal.

Grout joint width and tile variation: rectified tile allows narrow joints; non-rectified or handmade tile needs wider joints to absorb size variation and prevent lippage.

Grout cleanup timing: begin cleanup when grout firms up (a thumbprint stays but does not stick), use a damp sponge in a circular then diagonal motion, and change water often.

Efflorescence: white salt deposits on grout are removed with a mild acid or efflorescence remover after the grout cures; prevent it by limiting mixing water and avoiding wet curing.

Sealer application: apply a penetrating sealer to grout and porous stone with a small applicator, wipe excess from tile faces before it dries, and buff the surface.

Caulking changes of plane: fill the joint with backer rod where depth allows, apply silicone, and tool with a caulk tool or finger dipped in denatured alcohol.

Final inspection: check for lippage, hollow tile (tap test), consistent joint width, clean grout lines, and sealed movement joints before turning the job over.