Designed specifically for large-format tiles over 1200mm, Mapei Keraflex Maxi S1 Grey is a high-performance, flexible cementitious adhesive with no vertical slip and extended open time.
Its highly thixotropic formulation makes it particularly suitable for installing heavy and large-format tiles on vertical surfaces without sagging. Supplied as a grey powder composed of cement and finely graded sands, it contains a high quantity of synthetic resins and special performance additives developed in Mapei’s research laboratories.
Easy to work with and offering excellent adjustability time, Keraflex Maxi S1 hardens without appreciable shrinkage, delivering a durable and reliable bond for professional tiling projects.
Key features
Suitable for floor, outdoor and wall use throughout the home
Compatible with underfloor heating systems
Key facts
Colour
White
Room
Bathroom, Kitchen
Suitability
Floor, Outdoor, Wall
Suitable for Underfloor Heating
Yes
Weight
20kg
Sold per
Bag
Delivery and returns
Standard delivery£19.991 to 3 working days. Free over £299.
Next day delivery£35.00Order by 12pm, Monday to Friday.
Choose your day£25.00Pick a weekday at checkout, at least 3 working days ahead. Not offered when free samples are in your basket.
Delivering to Northern Ireland (BT postcodes)? Email [email protected] and we will arrange it. All prices Exc. VAT.
Yes, Mapei Keraflex Maxi Grey is suitable for both internal and external use, and its formulation is specifically designed to handle large format porcelain tiles as well as ceramics, mosaics, and moisture-stable stone. Its highly flexible S1 classification means it can accommodate slight movement in the substrate, which is particularly important in outdoor settings where temperature changes can cause expansion and contraction. It can be applied in a bed thickness of 3mm to 15mm, giving you the adjustment needed for uneven outdoor substrates.
Mapei Keraflex Maxi White is confirmed as suitable for use over plywood overlays and underfloor heating systems, making it a versatile choice for modern kitchen and bathroom installations. Its high flexibility helps absorb the minor movement generated by heating cycles, reducing the risk of tiles cracking or debonding over time. The white colourway is especially well suited to light-coloured tiles, translucent mosaics, or pale natural stone where a grey adhesive might show through and affect the finished appearance.
Mapei Keraflex Maxi Grey features a low dust formulation, which makes mixing considerably more comfortable compared to standard cementitious adhesives, and reduces the amount of airborne dust in your workspace. As a single part adhesive, it simply requires the addition of water – no separate polymer additive or liquid component is needed – making it straightforward for competent DIY installers as well as trade professionals. Its standard setting time gives you a reasonable working window to adjust tiles before the adhesive begins to cure.
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Often bought together
Ordering tiles too? Adhesive and grout have no minimum when they are in the same order as tiles.
“Excellent service and staff helped me to match my tiles and were responsive. Fast delivery and good product.”
Clare Gill23 October 2026
“customer service team and overall service were excellent. query and quote was dealt with quickly for the replacement of 6 tiles of a discontinued line which Stoke Tiles had in stock. delivery arrived within 24hrs of order being placed.”
Mike Holman12 October 2026
“Matt and Rich provide a professional tiling service and the quality of their work is unbeatable. I would not hesitate to recommend them.”
