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At a Glance: Key Applications
Use Keraflex Maxi S1 for: Installing large-format or heavy tiles on vertical and horizontal surfaces without slump or slip—perfect for residential bathrooms, external facades, and under-tile heating systems.
Keraflex Maxi S1: A Technical Overview
Mapei Keraflex Maxi S1 is a high-performance, deformable, cementitious adhesive designed for professional tile installations that demand superior bond strength, reduced vertical slip, and extended open time. Its creamy consistency and lightweight formulation make it ideal for large and heavy tiles, both on walls and floors. Suitable for internal and external use, it accommodates substrate movement thanks to its S1 deformability rating, providing long-term reliability across a wide range of substrates including heated screeds and waterproofing membranes.
Core Features & Specifications
- S1 deformable classification—ideal for substrates subject to slight movement or vibration.
- Non-slump formula—holds large and heavy tiles in place on walls without support.
- Extended open time (≥30 minutes)—allows for relaxed installation pace in hot or windy conditions.
- High initial grab—supports heavy tiles immediately after placement.
- Excellent coverage and workability—up to 5.5 m² with a 10 kg bag using a 10x10 trowel.
The Keraflex Maxi S1 Advantage
- Reduces tile lippage due to superior bed thickness control (up to 15 mm).
- Ensures long-term adhesion on challenging substrates like old tiles or heated floors.
- Accelerates site progress thanks to easy trowelability and extended working time.
- Minimises callbacks with durable, deformable adhesive matrix designed for movement tolerance.
Cure Profile & Performance
Pot life of 8 hours, open time ≥30 minutes, and ready for grouting after 8–16 hours depending on substrate and climate. Full cure in 14 days under standard conditions. Ideal for Australian climates—extended open time resists premature skinning in dry or windy regions.
Coverage Rate & Yield
Approx. 1.2 kg/m² per mm of thickness. A 20 kg bag covers approximately 5.5 m² when applied with a 10 x 10 mm notched trowel—ensuring excellent material efficiency even on large-format tiles.
Application & Service Temperature Range
Apply between +5°C and +35°C. Once cured, the adhesive is suitable for service in a wide temperature range, making it ideal for external facades and underfloor heating installations common in Australian builds.
Chemical Profile & Substrate Compatibility
Cement-based adhesive with proprietary polymers enhancing workability, bond strength, and flexibility. Resistant to water immersion and temperature cycling. Compatible with screeds, renders, waterproof membranes (e.g. Mapelastic Smart), and even over old tile surfaces with proper preparation.
Primer Requirements & Adhesion Protocols
For porous substrates like render and screeds, pre-wetting may be sufficient. On dusty or absorbent surfaces, use Eco Prim T Plus. Over waterproofing membranes or old tiles, ensure surface is clean and degreased—use Primer G or Eco Prim Grip for optimal bond.
Applications in Practice: Trade Scenarios
For Tilers: Large Format Wall Installations
The Engineering Challenge: Preventing slump and tile movement on vertical surfaces when working with heavy 600x1200 mm tiles.
The System-Based Solution with Keraflex Maxi S1: Its non-slip, lightweight formulation holds tiles in place with no spacers or battens required.
Best Practice Note: Back-butter large tiles and ensure full bed coverage with a 10 x 10 mm notch for optimal adhesion.
For Waterproofers: Under-Tile Heating ApplicationsThe Engineering Challenge: Adhesive cracking or delamination due to thermal movement on heated screeds.
The System-Based Solution with Keraflex Maxi S1: Its S1 deformability accommodates temperature-induced expansion without bond failure.
Best Practice Note: Allow screed to cure and dry fully. Prime with Eco Prim T before application.
Storage & Shelf Life Considerations
Store in original, unopened packaging in a dry area. Shelf life is 12 months. Protect from humidity and extreme heat common in northern Australian regions.
Certifications & Regulatory Compliance
Compliant with EN 12004 C2TE S1. Meets deformability requirements per AS ISO 13007.1 for S1 adhesives. Suitable for Green Star projects due to low VOC emissions.
Frequently Asked Questions About Mapei Keraflex Maxi S1
Q: Can Keraflex Maxi S1 be used over existing tiled surfaces?
A: Yes. When tiling over existing ceramic or porcelain tiles, clean the surface thoroughly to remove grease or contaminants, then apply Mapei Eco Prim Grip to enhance mechanical adhesion before applying Keraflex Maxi S1.
Q: Is Keraflex Maxi S1 suitable for heated screeds and underfloor heating systems?
A: Absolutely. Keraflex Maxi S1 is rated as a deformable (S1) adhesive, which allows it to accommodate expansion and contraction associated with under-tile heating, preventing adhesive failure or tile cracking.
Q: How thick can Keraflex Maxi S1 be applied?
A: It can be applied up to 15 mm thick in a single pass, which is ideal for leveling minor substrate irregularities and supporting heavy tiles without additional bedding.
Q: What is the open time and working time for Keraflex Maxi S1?
A: The adhesive maintains an extended open time of ≥30 minutes and a pot life of up to 8 hours, allowing flexibility on site, especially in hot or windy conditions.
Q: Do I need to use a primer before using Keraflex Maxi S1?
A: It depends on the substrate. On porous or dusty surfaces, use a primer like Eco Prim T. On smooth, non-absorbent substrates such as waterproofing membranes or old tiles, use Eco Prim Grip for best results.
Applications & Benefits
| Application / Use Case | Key Benefit | Primary Trades |
|---|---|---|
| Large Format Wall Tiling | Non-slip formulation holds heavy tiles in place | Tilers, Builders |
| Under-Tile Heating Systems | S1 deformability resists cracking from thermal movement | Waterproofers, Builders |
| Facade Cladding & External Walls | High bond strength with long-term durability outdoors | Tilers, Builders |
| Tiling Over Existing Tiles | Adheres to glazed surfaces with primer for renovation jobs | Tilers, Renovators |
| Wet Area Tiling (Showers, Balconies) | Compatible with Mapei waterproofing membranes | Waterproofers, Tilers |
Applying Mapei Keraflex Maxi S1: Protocols & Best Practices
General Application Steps:- Preparation: Ensure the substrate is clean, dry, and prepared as per the Adhesion & Preparation Guide. Use appropriate primer where required.
- Application: Mix with clean water using a mechanical stirrer until lump-free. Apply using a notched trowel suited to tile size, ensuring full contact.
- Tooling & Finishing: Adjust tiles within the open time (≥30 mins). Use spacers if needed. Check bed coverage, especially on external applications.
- Curing: Allow to set undisturbed. Grouting may commence after 8–16 hours depending on substrate and ambient temperature.
For Tilers: Large Format Wall Installations
The Engineering Challenge: Preventing vertical slip of heavy tiles without spacers or battens.
The System-Based Solution with Keraflex Maxi S1: The thixotropic, non-slump formula securely holds large tiles in place on vertical surfaces.
Best Practice Note: Use back-buttering technique for full coverage and stronger adhesion, especially for tiles over 600 mm in width.
For Waterproofers: Under-Tile Heating Applications
The Engineering Challenge: Avoiding adhesive failure due to thermal expansion from heating systems.
The System-Based Solution with Keraflex Maxi S1: Its deformable adhesive structure absorbs movement without debonding or cracking.
Best Practice Note: Prime heated screeds with Eco Prim T and ensure heating is switched off 24 hours before and 5 days after tiling.
Limitations & Safety
Product limitations and safety information
Limitations:
- Not suitable for substrates with permanent moisture rising (e.g. green concrete or unsealed screeds).
- Do not apply below +5°C or above +35°C ambient temperature.
- Not for use on metal, rubber, or plastic surfaces.
Safety & Handling:
- PPE: Use gloves, dust mask, and safety glasses when mixing or applying.
- Ventilation: Use in well-ventilated areas, especially indoors.
- Handling: Avoid prolonged skin contact. Wash with soap and water after handling.
- First Aid: In case of contact with eyes or ingestion, rinse thoroughly and seek medical attention as per ASCC guidelines.
Mapei Keraflex Maxi S1 Adhesion & Preparation Guide
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Substrate preparation guidelines
- Concrete Screeds: Clean, dry, and free from dust or laitance. – Primer: Eco Prim T Plus (if absorbent).
- Existing Ceramic Tiles: Clean thoroughly and degrease. Mechanically roughen if glossy. – Primer: Eco Prim Grip.
- Plasterboard or Fibre Cement Sheets: Ensure sheets are stable and clean. – Primer: Not typically required unless dusty.
- Waterproofing Membranes (Mapegum WPS, Mapelastic Smart): Fully cured and clean. – Primer: Eco Prim Grip recommended.
- Heated Floors (Electric or Hydronic): Ensure system is off and substrate is dry. – Primer: Eco Prim T (porous screeds).
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