Ardex S21 Rapid Setting Tile Bedding Mortar Grey 22kg (1 Unit)
Ardex S21 Rapid Setting Tile Bedding Mortar Grey 22kg (1 Unit)
- Suitable for fixing floor tiles, pavers, natural stone, etc
- Use with sharp sand to form ramps and pre-level subfloors
- Rapid hardening formulation allows tiles to be grouted and walked on after 3 hours
- Pourable consistency achieves solid bed fixing with ease
- Ideal for almost all tile types including non-moisture sensitive natural stone
- Suitable for internal and external areas
In Stock Next Day Delivery | Order Before 12 PM | Subject to Stock Availability
Trade account pricing available
Exclusive contractor & developer rates.
No minimum order required.
TileExperience Trade Account
Save up to 15% on thousands of products with exclusive trade pricing and dedicated account support.
| Type | Mortar |
|---|---|
| Brand | Ardex |
| Coverage | Approximately 4.0m2 at 3mm thick per 22kg bag |
ARDEX S 21 Rapid Setting Floor Tile Bedding Mortar
For solid bed fixing of large format tiles and natural stone – walk on and grout after just 3 hours.
ARDEX S 21 is a high-performance, rapid-setting and hardening floor tile bedding mortar formulated for solid bed fixing of large format tiles, brick pavers, and natural stone. Its pourable consistency allows for effortless solid bedding without voids, while the fast-curing formula enables grouting and light foot traffic after only 3 hours. ARDEX S 21 can also be mixed with sharp sand to form ramps, falls, or pre-level subfloors, making it an exceptionally versatile solution for internal and external installations.
Key Features & Benefits
- Rapid setting and hardening: Walk on and grout tiles after 3 hours.
- Ideal for large format tiles, pavers, and non-moisture-sensitive natural stone.
- Pourable, solid-bed consistency for full coverage without voids.
- Use with sharp sand to form ramps and pre-level uneven floors.
- Internal and external use including swimming pools and wet areas.
- Suitable with under-tile heating systems when used with ARDEX E 90 Mortar Admix.
- Grey colour – ideal for general floor installations.
- Low embodied carbon: 0.49 kg CO₂ eq/kg (A1–A3 production stage).
Ideal Applications
ARDEX S 21 is designed for a wide range of floor tiling projects in both residential and commercial environments, including:
- Fixing large format ceramic, porcelain, and natural stone floor tiles.
- Installing brick pavers and terrazzo tiles.
- Creating ramps, slopes, and pre-levelled subfloors with the addition of sharp sand.
- Internal and external areas, including wet rooms, swimming pools, and balconies.
Technical Data
| Colour | Grey |
| Unit Size | 22kg bag |
| Bed Thickness | 2–10mm (up to 30mm with sharp sand inclusion) |
| Pot Life | 30 minutes |
| Open Time | 10 minutes |
| Adjustment Time | 20 minutes |
| Grout After | 3 hours |
| Coverage | Approx. 4.0m² at 3mm thickness per 22kg bag |
| Embodied Carbon (A1–A3) | 0.49 kg CO₂ eq/kg |
| Bulk Density (Powder) | Approx. 1.4 kg/litre |
| Weight of Fresh Mortar | Approx. 2.1 kg/litre |
| Initial Set (Vicat) | Approx. 30 minutes |
| Final Set (Vicat) | Approx. 1.5 hours |
| Compressive Strength | 8.0 N/mm² (1 day), 30.0 N/mm² (28 days) |
| Tensile Bending Strength | 3.0 N/mm² (1 day), 10.0 N/mm² (28 days) |
| Adhesion Strength | ≥0.5 N/mm² under all test conditions |
Mixing Instructions
Add ARDEX S 21 powder to clean water in a clean mixing container while stirring continuously. Mix thoroughly to achieve a pourable, workable mortar. For best results, use an ARDEX mixing paddle with a variable-speed drill.
- Mix ratio: Approx. 4½ parts powder to 1 part water.
- Water requirement: 3.5 litres of clean water per 22kg bag.
- Working time: Approx. 30 minutes at 20°C.
- For underfloor heating or additional flexibility, replace water with a mixture of 2kg ARDEX E 90 and 2 litres of water.
The consistency can be adjusted for semi-dry or fluid applications as needed.
Application
Apply ARDEX S 21 to the prepared surface using a trowel, then comb through with a suitable square-toothed notched trowel to create even ribs. Its pourable consistency allows solid bed fixing in one operation without the need for buttering, ensuring no voids beneath tiles. Tiles should be fixed within the 10-minute open time for best results.
Grouting & Curing
Tiles fixed with ARDEX S 21 can be grouted and walked on after just 3 hours at 20°C, ensuring minimal downtime and faster project turnaround.
Packaging, Coverage & Storage
- Packaging: 22kg paper sack with polyethylene liner.
- Coverage: Approximately 1.8kg/m²/mm thickness.
- Storage: Store in a cool, dry place, off the ground, and protected from moisture.
- Shelf life: 12 months from date of manufacture (unopened packaging).
Why Choose ARDEX S 21?
ARDEX S 21 Rapid Setting Bedding Mortar delivers exceptional performance for demanding floor installations. Whether fixing large porcelain tiles, forming ramps, or working in wet areas, its rapid strength development, easy mixing, and versatile consistency make it the professional’s choice for both speed and durability.
FAQs
Q: How soon can I walk on tiles fixed with ARDEX S 21?
A: Tiles can be walked on and grouted after approximately 3 hours at 20°C.
Q: Can ARDEX S 21 be used outdoors or in wet areas?
A: Yes, ARDEX S 21 is suitable for both internal and external installations, including wet rooms and swimming pools.
Q: Can I use ARDEX S 21 with under-tile heating systems?
A: Yes, provided it is mixed with ARDEX E 90 Mortar Admix for additional flexibility and adhesion.
Q: What bed thickness can ARDEX S 21 achieve?
A: Standard bed thickness is 2–10mm. Applications above 10mm can be achieved by incorporating coarse sharp sand.
UK Mainland & Scottish Highlands only
We do not deliver to Islands, Ireland or Northern Ireland
How is shipping calculated?
Shipping is based on your order weight and delivery location. Add items to your cart and enter your postcode to see the exact cost before checkout.
Some products supplied directly from our manufacturers (non-stocked brands) carry a separate delivery charge — this is shown clearly at checkout.
Free delivery on orders £450+ inc VAT
Tiles & tiling materials only · Free samples always ship free
Next working day delivery
Order before 12:00 pm · From £6.50 + VAT · APC Overnight or DPD · Under 50 kg
Not available weekends or bank holidays
No next-day to Scotland postcodes
AB · IV · KW · PA — please allow additional working days for these regions
Pallet delivery — orders over 50 kg
Semi, half or full pallet · Palletways or K & R Mason · Next working day
Kerbside delivery only — driver cannot bring goods onto the property
Supplier direct delivery (non-stocked products)
Some brands are shipped directly from the manufacturer and carry a separate delivery charge, shown at checkout.
Genesis (trims) — £19 + VAT · 1–3 days · cut-off 11:00 am
Marmox (mosaics, shower trays) — £15 + VAT · 1–3 days
Marmox (oversized backing boards) — £65 + VAT · 1–3 days
Schluter (trims) — £20 + VAT · 1–3 days
Bihui (trims) — £15 + VAT · 1–3 days
Free sample delivery
No minimum spend · Up to 4 free samples · Next working day
Free Click & Collect
Select Click & Collect at checkout to pick up your order from our Croydon warehouse. We'll send an email confirmation once it's ready — please wait for this before visiting.
Bring your order confirmation email or order number when collecting.
If someone is collecting on your behalf, they must have the order number and the name on the order.
Mon – Fri, 8:30 am – 4:30 pm. Closed weekends & bank holidays.
Tile Experience, 108 Beddington Lane, Croydon, London, CR0 4YY
Order tracking
Email or SMS sent by the carrier once your order is dispatched
30-day return window
Returns accepted within 30 days of delivery. You also have a statutory 14-day cancellation right from the date of receipt.
Items must be unused & in original packaging
Returned goods must be uninstalled, unaltered and in the same condition as received.
Installed or cut items cannot be returned
Once tiles or materials have been cut, altered or installed, no return or refund is possible under any circumstances.
How to start a return
Contact us first at info@tileexperience.co.uk or call 0208 689 4187. Send the item back with your name and order number. Return shipping is the customer's responsibility.
Refund to original payment method
Processed within 3–5 working days of us receiving and approving your return.
Original delivery charges are not refunded. If no refund after 15 business days, contact us.
Damaged or incorrect items
Report within 48 hours of receipt. Email info@tileexperience.co.uk with your order number and photos of the damage. Confirmed replacements are sent next working day at no charge.
Non-stocked brands — restocking fee may apply
Returns for Genesis, Marmox and Bihui carry up to a 20% restocking fee. Schluter trims: 35% standard return, 15% if returning with a replacement order.
Cancellations
Cancel before dispatch for a full refund including delivery. Cancel after dispatch by rejecting the delivery — refund for goods only, not the delivery charge.
-
