Ardex Grout Booster

When grouting tiles on timber floors, plasterboard, chipboard, or heated sub-floors, standard cement-based grouts risk cracking under structural movement. ARDEX Grout Booster replaces or dilutes the mixing water to build high-grade polymer flexibility, water repellency, and adhesion into cement-based ARDEX grouts across floor and wall applications.

How it works

By replacing mixing water with a synthetic polymer emulsion, this additive increases the flexibility and elastic properties of the grout. This allows the joints to absorb the movement of flexible timber sub-floors, plywood backings, and the thermal expansion of heated sub-floors. The polymer modification also improves adhesion to dense tile edges (fully vitrified tiles, ceramic tiles, and porcelain) while increasing abrasion strength to prevent dry, powdery joints in heavy pedestrian traffic areas. On external cladding and balconies, the additive creates water-repellent joints and helps reduce efflorescence, while in swimming pools and showers, it resists water penetration and stabilizes the curing process to preserve grout colour.

Numbers that matter

• 100% booster ratio: The full-strength mixture required for ARDEX Wide Joint in high-exposure swimming pools and flexible timber floors.
• 80% booster / 20% water ratio: The specified mix ratio for ARDEX FG8 and ARDEX FS-DD when grouting in swimming pools or over timber floors.
• 50% booster / 50% water ratio: The dilution standard for general tiling installations to improve colour and adhesion, and add water resistance.
• 24 hours: The time required before the treated grout can be opened to traffic.
• 14 days: The timeframe required to reach a full chemical cure.

Where to use it

Suitable for internal and external, commercial and residential wall and floor tiling. Use it with ARDEX cement-based grouts on fully vitrified tiles, ceramic tiles, porcelain, moisture-insensitive natural stones, and mosaics in kitchens, bathrooms, showers, swimming pools, balconies, and on external cladding.

Limitations

• Do not use with cement-based ARDEX grouts for chemical-resistant joints; use ARDEX epoxy grout instead.
• Do not use for expansion or movement joints; use ARDEX silicone sealant.
• Do not apply in temperatures below 8°C or above 35°C.
• Do not allow the grout mixture to dry on the tile surface, as cleaning becomes difficult once the polymer booster has been incorporated. Test ease of cleaning on textured, porous, or matt tile surfaces before starting the job.

Mixing guide

Shake or stir ARDEX Grout Booster before use. Mix the required volume with clean water in a clean container according to the application type, then gradually add the grout powder while stirring to achieve a lump-free, low-slump mortar.

• ARDEX Wide Joint (per 20kg): Requires 2.5L to 3.0L total liquid. Use 100% Grout Booster for swimming pools and timber floors, or a 50/50 water dilution for general tiling.
• ARDEX FG8 (per 20kg): Requires 4.2L to 4.4L total liquid. Use 80% Grout Booster / 20% water for swimming pools and timber floors, or a 50/50 water dilution for general tiling.
• ARDEX FS-DD (per 20kg): Requires 6.0L total liquid. Use 80% Grout Booster / 20% water for swimming pools and timber floors (not applicable for general tiling dilution).