MasterSeal® M 266 Non-Fibrated Bitumen Emulsion — Damp-Proofing Coating
Two-component, cold-applied polyurethane liquid membrane that cures to form a seamless, highly flexible, and fully elastomeric waterproof coating for below-ground structures, wet areas, roofs, and internal damp-proofing applications. Chemical curing system — does not rely on atmospheric moisture.
Performs reliably under sustained 45°C+ summer temperatures. The two-component chemical curing system is not reliant on atmospheric moisture — maintaining consistent curing performance in UAE's variable humidity conditions. Engineered for coastal UAE environments including Abu Dhabi and Dubai, where salt-laden humidity and high thermal cycling demand an elastomeric membrane with exceptional elongation and adhesion.
UAE's trusted construction chemistry partner — expert coordination, authentic supply, site-ready delivery.
What is MasterSeal® M 266?
MasterSeal® M 266 is a two-component, polyurethane, liquid-applied waterproof coating engineered to create a highly flexible, seamless, and elastomeric waterproof membrane for wet areas, below-grade structures, and exposed concrete substrates. Once both components are mixed and applied, the system chemically cures into a durable waterproof layer with high tensile strength, strong adhesion, and excellent crack-bridging performance.
It forms a high-elongation elastomeric membrane capable of accommodating substrate movement, thermal expansion, and minor structural cracking without membrane failure. The coating achieves elongation values of approximately 700% with bond strength greater than 1 MPa to concrete surfaces — making it highly suitable for UAE structures exposed to intense thermal cycling and concrete movement. The two-component chemical curing system does not rely on atmospheric moisture for curing, ensuring consistent performance in UAE's variable humidity conditions.
Key Performance Benefits
- Highly flexible polyurethane membrane with elongation up to approximately 700% (ASTM D412)
- Seamless liquid-applied system — eliminates lap joint leakage risks common in sheet membranes
- Excellent crack-bridging capability for concrete movement and thermal expansion
- Strong adhesion to concrete, cement screeds, masonry, and related construction substrates (>1 MPa)
- Two-component chemical curing — does not rely on atmospheric moisture for curing
- Suitable for wet areas, balconies, bathrooms, roofs, podium decks, and below-grade waterproofing
- Impermeable against water penetration — tested under 3 m head of water for 30 minutes
- Resistant to mildew, frost, and aggressive environmental exposure
- High tensile strength and durable elastomeric performance after curing
- Can be reinforced with glass fibre mesh for critical waterproofing details and movement areas
Pour Part B into a clean container first, then add Part A while stirring. Mix thoroughly with slow-speed drill and paddle attachment until a uniform, streak-free consistency is achieved. Do not partially mix — incomplete mixing results in uncured patches in the membrane. Use only factory pre-measured packs to maintain the correct mix ratio.
Coverage — 1 Kit Yield
Mechanical & Physical Properties
| Composition | Two-component polyurethane system |
| Colour | Black / Dark |
| Solid Content | > 90% |
| Density | ~1.3 kg/litre (mixed) |
| Tensile Strength | 3 N/mm² (ASTM D412) |
| Elongation at Break | ~700% (ASTM D412) |
| Bond Strength (concrete) | >1 MPa |
| Water Impermeability | Impermeable at 0.3 MPa / 30 min |
| Min. DFT | 1.2 mm total across 2 coats |
| Shelf Life | 12 months from date of manufacture |
| Quality Certifications | ISO 9001 / ISO 14001 |
Application Parameters
| Application Method | Brush, roller, or squeegee |
| Minimum Coats | 2 coats minimum |
| Min. DFT per Coat | 1 mm per coat (with reinforcement) |
| Total Min. DFT | 1.2 mm across both coats |
| Pot Life (25°C) | >50 minutes |
| Drying Time | <24 hours |
| Min. Application Temp | +5°C |
| Max. Application Temp | +40°C |
| Reinforcement Option | Glass fibre mesh embedded between coats |
Packaging — UAE
| 28 Kg Kit | Part A (8 kg pail) + Part B (20 kg container) |
Application Guide — UAE Site Conditions
Follow these steps for optimum elastomeric waterproofing performance with MasterSeal® M 266 in UAE's hot, coastal, and high-humidity environments.
Surface Preparation
The substrate should be smooth, clean, and free of laitance, grease, oils, and standing water. Repairs to the substrate, filling of joints, blowholes/voids, and surface levelling must be carried out before application. Thoroughly wire brush the surface and clean dust by air compressor or water jetting. Remove oil and grease using degreasing solvents. Repair any damaged surface using crack fillers or polymer-modified repair mortar. Address any leakages in concealed pipes or other water sources prior to application. Very weak plaster must be replaced. The substrate must be properly pre-wetted to a saturated surface-dry (SSD) condition.
Mixing
Pour Part B into a separate clean container first, then add Part A while stirring/agitating. Mix thoroughly using a slow-speed drill with a paddle attachment until a uniform, streak-free consistency is achieved. Do not partially mix — incomplete mixing of the two components results in uncured patches in the membrane. Use only factory pre-measured packs to maintain the correct mix ratio. One 28 kg kit yields approximately 21.53 litres.
First Coat Application
Apply the first coat uniformly by brush, roller, or squeegee to the prepared damp substrate at a minimum of 1 mm DFT per coat, ensuring full coverage with no missed areas or pinholes. Pay particular attention to corners, upstands, junctions with walls, and penetrations — these are the most common failure points and should receive additional attention or a coved fillet detail.
Reinforcement (Where Required)
Where superior performance is required — movement joints, cracks, penetrations, and detail areas — reinforce the membrane with a layer of glass fibre mesh. Embed the mesh into the wet first coat while it is still fresh, ensuring full encapsulation. Each coat must achieve a minimum of 1 mm DFT when reinforcement is used. Allow the first coat to fully encapsulate the mesh before applying the second coat.
Second Coat Application
Apply the second coat in a crosswise direction to the first coat, but only after the first coat has cured sufficiently to accept foot traffic without damage. The total applied dry film thickness across both coats must be a minimum of 1.2 mm for below-ground structures, wet areas, and roofs. Ensure no areas are left uncovered.
Storage & Shelf Life
Store in a dry and shaded area away from direct sunlight and heat. Shelf life is 12 months from the date of manufacture. In UAE conditions, store components in air-conditioned warehousing — elevated storage temperatures shorten shelf life and may affect mix viscosity and performance. Do not use expired material.
Complete Mixing
Do not partially mix components — incomplete mixing produces uncured, soft patches in the cured membrane. Always use factory pre-measured full kits to ensure correct mix ratio. Never split partial packs without weighing accurately.
Pot Life in Heat
Pot life reduces significantly above 35°C. In UAE summer, mix only what can be applied within 20–25 minutes. Store components in air-conditioned space immediately before use. Begin application early morning before temperatures peak.
Minimum 2 Coats
Always apply a minimum of two coats in crosswise directions. A single coat cannot guarantee a pinhole-free membrane and will not achieve the minimum 1.2 mm DFT required for reliable waterproofing performance.
Recommended System Products
Combine MasterSeal® M 266 with these Highway BMT-stocked products for complete waterproofing, curing, admixture, and joint protection systems across UAE wet areas, roofs, podiums, basements, and below-grade structures.