ARDEX S 21 is a rapid-hardening, pourable cement-based floor tile bedding mortar for internal and external use, including swimming pools. Classified C1 F to BS EN 12004, it suits large tiles, ceramic and brick pavers, terrazzo tiles and non-moisture-sensitive natural stone, and can be mixed with screeding sand to pre-level sub-floors and form ramps. Tiles can be grouted and walked on after approximately 3 hours.

Key Benefits

Application

Add to clean water — approx. 3½ litres per 22kg bag — and mix to a pourable mortar (working time approx. 30 minutes at 20°C). Apply and comb through with a square-notched trowel; minimum bed thickness 2 to 3mm. Fix tiles within 10 minutes. For levelling, use neat up to 10mm, or mix with approx. 20kg of screeding sand per bag for 10mm to 30mm over a bonding coat of neat S 21. Apply above 5°C.

Coverage

Approx. 1.8 kg/m² per mm bed thickness — a 22kg bag fixes approx. 4m² at 3mm or 2.5m² at 5mm. Coverage varies with tile size, substrate and trowel notch size.