Gloved hand spreading mortar for a tile installation

Reference

How long does grout take to dry

Cement grout and thinset cure rather than dry (premixed grout does dry), and each has three waits that matter: before you walk on it, before it gets wet, and before you seal it. The joint widths that decide how much grout you need are on the tile sizes and grout joints guide.

How long before you can walk on grout? 24 hours. Keep it dry for 72 hours, seal cement grout after 72 hours, and treat it as fully cured at 28 days. Epoxy grout is ready for water in 72 hours and does not need sealing; premixed grout can need up to a week before a shower.

How long does grout take to cure, by type

Grout	Walk on	Water / shower	Seal	Full cure
Cementitious, sanded Amazon	24 hours	72 hours	72 hours	28 days
Cementitious, unsanded (1/16 in joints) Amazon	24 hours	72 hours	72 hours	28 days
Premixed acrylic or urethane Amazon	24 hours	3–7 days (check the pail)	no sealer needed	3–7 days
Epoxy Amazon	24 hours	72 hours	no sealer needed	14 days

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Don't grout below 50 °F. In a cool room (50–60 °F) or high humidity, allow up to twice as long. Showers: use the water wait for your grout type — premixed grouts can need up to 7 days.

How long does thinset take to dry

Mortar	Open time after spreading	Grout after	Heavy traffic	Full strength
Polymer-modified thinset	30 minutes	24 hours	7 days	28 days
Unmodified (dry-set) mortar	20 minutes	24–48 hours	7 days	28 days
Large-format / medium-bed mortar	35 minutes	24 hours (8–16 on walls)	7 days	28 days
Rapid-setting thinset	15 minutes	2–4 hours	1 day	28 days

Full strength is what to wait for before filling a pool or tub surround. Over a waterproofing membrane or uncoupling mat the mortar dries slower; allow the longer end of every wait before grouting.

Grout coverage chart

Pounds of dry grout per square foot, by tile size and joint width, for tile ⅜ in thick (¼ in for 4 × 4 and 6 × 6 wall tile). Grout comes in boxes of 7–10 lb and bags of 25 lb; 1/16 in joints take unsanded grout.

Tile	1/16 in joint	1/8 in joint	3/16 in joint	25 lb bag covers (⅛ in)
4 × 4 in	0.07 lb/sq ft · 0.34 kg/m²	0.14 lb/sq ft · 0.68 kg/m²	0.22 lb/sq ft · 1.07 kg/m²	179 sq ft · 16.6 m²
6 × 6 in	0.05 lb/sq ft · 0.24 kg/m²	0.09 lb/sq ft · 0.44 kg/m²	0.14 lb/sq ft · 0.68 kg/m²	278 sq ft · 25.8 m²
12 × 12 in	0.04 lb/sq ft · 0.20 kg/m²	0.07 lb/sq ft · 0.34 kg/m²	0.11 lb/sq ft · 0.54 kg/m²	357 sq ft · 33.2 m²
12 × 24 in	0.03 lb/sq ft · 0.15 kg/m²	0.05 lb/sq ft · 0.24 kg/m²	0.08 lb/sq ft · 0.39 kg/m²	500 sq ft · 46.5 m²
24 × 24 in	0.02 lb/sq ft · 0.10 kg/m²	0.04 lb/sq ft · 0.20 kg/m²	0.05 lb/sq ft · 0.24 kg/m²	625 sq ft · 58.1 m²

Thinset coverage per bag

Square feet per 50 lb bag, by trowel notch. Back-buttering large tile uses noticeably more — allow about 25%.

Trowel	50 lb bag covers	Bags per 100 sq ft
1/4 x 1/4 in square notch	90 sq ft · 8.4 m²	1.1
1/4 x 3/8 in square notch	65 sq ft · 6.0 m²	1.5
1/2 x 1/2 in square notch	40 sq ft · 3.7 m²	2.5

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Figures: Grout times: Custom Building Products Polyblend Plus sanded and non-sanded data sheets (light foot traffic after 16–24 hours, keep above 50 °F for 72 hours, do not install below 50 °F); Mapei Keracolor technical data sheets (light foot traffic about 24 hours); Laticrete SpectraLOCK Pro Premium data sheet (epoxy: light traffic 12 hours, full cure 14 days at 70 °F); Mapei Flexcolor CQ (3 days before intermittent water) and Custom Fusion Pro (7 days) data sheets for premixed grout; the 72-hour wait before sealing cement grout is the grout and sealer makers' guidance. Coverage: Custom Building Products TDS-360 coverage chart (a 25 lb bag at a 1/8 in joint covers about 348 sq ft of 12 × 12 tile, 461 of 12 × 24, 688 of 24 × 24), scaled by (length + width) ÷ (length × width) × joint width × tile thickness. Thinset: Mapei Ultraflex 2 (30 min open time, 16–24 hours before grouting), Mapei Kerabond (20 min, 24 hours on floors), Mapei Ultraflex LFT (30–35 min, 24 hours on floors, 8–16 on walls, 28 days before water immersion) and Custom VersaBond Flex data sheets; rapid-set: Custom VersaBond LFT RS. Coverage per trowel notch from the same sheets: the page uses 90, 65 and 40 sq ft per 50 lb bag for the 1/4 x 1/4, 1/4 x 3/8 and 1/2 x 1/2 notches, which is the low-to-middle of the published ranges (Custom VersaBond TDS-119: 90–100, 60–67 and 42–47 sq ft), so the bag count errs toward buying enough. Custom does not recommend the 1/2 x 1/2 square notch for large tile and prefers a 3/4 x 9/16 x 3/8 U-notch. Back-buttering allowance: the same sheets' large-tile guidance. Accessed 2026-10-14. The data sheet for the product you bought has the final word on times.

Grout and thinset questions

How long before grouting tile?

24 hours for modified thinset (24–48 hours for unmodified or over a membrane), 2–4 hours for rapid-setting mortar — so the thinset has firmed up and the tile does not shift under the float.

How long after grouting can you walk on tile?

24 hours for light foot traffic in socks; keep furniture and water off for 72 hours.

How long does grout take to cure before sealing?

72 hours for cement grout. Premixed and epoxy grouts don't need sealing.

Can I shower after 24 hours, and what if grout gets wet too early?

No — cement grout needs 72 hours, premixed up to 7 days. Water in the first day washes pigment and cement out of the joint, leaving it soft, light-colored or powdery; let it dry out fully, then rake and regrout the damaged joints.

How much grout per square foot?

From 0.02 lb for 24 × 24 tile at a 1/16 in joint to 0.22 lb for 4 × 4 at 3/16 in.

Tools for the job

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