Red Seal Tilesetter flashcards
Red Seal Tilesetter · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Silica dust control
- Respirable crystalline silica is released when cutting tile, stone, or concrete dry. Use wet cutting or dust extraction; OSHA 1926.1153 Table 1 specifies controls and respirators by task.
- Thinset coverage estimate
- A 50 lb bag of thinset covers about 60–70 sq ft with a 3/16 x 1/4 in V-notch, but only 30–40 sq ft with a 1/2 x 1/2 in square notch.
- Tile waste factor
- Add 10% for straight layouts, 15% for diagonal or running bond, and 20% or more for mosaics, herringbone, or jobs with many cuts.
- SDS review
- The Safety Data Sheet lists pH, flash point, ventilation, and PPE requirements for a product. Review it before first use of any chemical.
- Installation sequence
- Substrate prep, layout, waterproofing and movement joints, tile setting, cure, grouting, cure, sealing if required, final clean.
- Concrete RH test
- ASTM F2170 in-situ relative humidity probes determine slab moisture. Most cementitious thinsets require RH of 75–80% or less before installation.
- Substrate flatness tolerance
- Floors must vary no more than 1/4 in in 10 ft and 1/16 in in 12 in; walls no more than 1/4 in in 10 ft per ANSI A108.01.
- Deflection limits
- Wood subfloors must meet L/360 for ceramic tile and L/720 for stone per TCNA. Check joist size, spacing, span, and subfloor thickness before tiling.
- Crack isolation membrane
- ANSI A118.12 membrane decouples tile from substrate movement. Required over cracked slabs, control joints, and embedded in-floor heat.
- Wet-area waterproofing
- ANSI A118.10 membranes are required in showers, tub surrounds, and laundry areas. Bond to substrate with thinset and overlap seams per manufacturer.
- Gypsum drywall limitation
- Drywall is not acceptable as a tile substrate in wet areas. Use cement backer board (ANSI A118.9) or foam backer board approved for wet areas.
- 3-4-5 squaring method
- Measure 3 ft along one wall and 4 ft along the perpendicular, then adjust until the diagonal is 5 ft. This establishes a 90° reference line.
- Centerline layout rule
- Find the room center by measuring between opposing walls. Adjust so cut tiles at opposite walls are equal and at least half a tile wide.
- Diagonal tile span
- The diagonal of a square tile equals side length × 1.414. A 12 in tile spans about 17 in on the diagonal.
- Grout joint width
- Use 1/16–1/8 in for rectified porcelain, 3/16–1/4 in for pressed-edge ceramic and stone, and 1/4–3/8 in for saltillo or tumbled stone.
- Movement joint spacing
- Per TCNA EJ171, place movement joints every 20–25 ft interior and 8–12 ft exterior, plus at changes in plane, perimeters, and dissimilar materials.
- Full-tile at threshold
- Place full tiles at the most visible entry or doorway and push cut tiles to less visible walls.
- Trowel notch selection
- Notch depth should roughly equal tile thickness. Back-butter large-format tile and achieve at least 80% coverage dry, 95% wet or exterior.
- Glass tile adhesive
- Use a white modified thinset (ANSI A118.4) to prevent shadowing. Avoid dark adhesives and cut with a wet saw, not a snap cutter.
- Large-format tile handling
- Tiles 15 in or larger require back-buttering, a slant-notch or 1/2 x 1/2 in trowel, and a leveling clip system to control lippage.
- Stone back-sealing
- Seal the back and sides of porous stone such as travertine, limestone, and marble before setting. Use white thinset for light stones to prevent bleed-through.
- Cure before grouting
- Wait at least 24 hours for cementitious thinset and 24–72 hours for epoxy adhesives before grouting, per manufacturer instructions.
- Perimeter gap
- Leave a 1/4 in gap at perimeter walls and fill with flexible sealant meeting ASTM C920, not grout.
- Sanded versus unsanded grout
- Use sanded grout for joints 1/8 in or wider; unsanded for joints under 1/8 in and for polished stone and glass, since sanded grout can scratch.
- Grout mixing accuracy
- Measure water precisely per bag instructions. Over-watering weakens grout and causes efflorescence and color variation.
- Grout curing time
- Keep joints damp or use a curing membrane for 24–72 hours. Avoid foot traffic for 24 hours and heavy traffic for 72 hours.
- Efflorescence removal
- White salt deposits on grout are removed with a diluted acid wash such as sulfamic acid after the grout has cured. Rinse thoroughly and neutralize.
- Sealing cementitious grout
- Cementitious grout is porous and benefits from a penetrating sealer after full cure, typically 72 hours. Reapply per manufacturer.
- Hollow tile repair
- Break out the tile from the center with a chisel, clean the substrate, and reset with modified thinset. Match grout color with a test batch.
- Change-of-plane caulk
- Caulk all changes in plane and perimeter joints with 100% silicone or siliconized acrylic matching grout color.
- Epoxy grout use
- Epoxy grout is specified for high-chemical or high-traffic areas. It is less porous than cementitious grout but requires precise mixing and short working time.
- Tile haze removal
- Buff grout haze from tile with a clean dry cloth after the grout has set but before full cure. Avoid acidic cleaners on acid-sensitive stone.