FAST-SET is Schluter's rapid-setting modified thin-set mortar — it does the same job as ALL-SET but cures much faster. In practical terms, you can grout 4 hours after setting tile (vs. overnight with standard mortars). That makes it the go-to for time-sensitive jobs: rental turnovers, one-day bathroom remodels, commercial projects where downtime costs money.

Like ALL-SET, it's specifically formulated to work with Schluter membranes and substrates. It bonds to DITRA, KERDI, KERDI-BOARD, and all standard tile substrates without requiring a latex additive — just add water.

When to use FAST-SET vs. ALL-SET

• FAST-SET: When you need to grout the same day, or when the space needs to be operational quickly. Also good in cooler environments where standard mortars cure slowly.
• ALL-SET: When you have overnight cure time and want a longer working window. ALL-SET gives you more time to adjust tiles before it sets.
• Both: Modified thin-set, bonds to all Schluter products, just add water

Key specs

• Type: Rapid-setting modified thin-set mortar
• Mix: Add water only — no liquid latex additive needed
• Pot life: Shorter than ALL-SET (work in smaller batches)
• Grout-ready: ~4 hours after tile installation
• Foot traffic: ~4 hours
• Compatible with: DITRA, DITRA-HEAT, KERDI, KERDI-BOARD, concrete, plywood, cement board
• Available in: 12.5 lb and 25 lb bags

Installation tips

• Mix in small batches — it sets fast, and once it starts firming up, adding more water won't help
• Don't remix. If it stiffens in the bucket, throw it out and mix fresh
• Use within the pot life window — don't try to stretch it
• In hot weather or on absorptive substrates, dampen the surface first to prevent premature drying
• Store bags in a dry area — moisture kills the rapid-set chemistry

Pairs with

• All Schluter membranes (DITRA, KERDI, DITRA-HEAT)
• KERDI-BOARD panels
• Any porcelain, ceramic, or natural stone tile