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RAINPROOF PU 400
- Bathroom floor leakage
- Under-tile wet area waterproofing
- Balcony and terrace waterproofing
- Waterproofing water-retaining structures
RAINPROOF PU 400 is a single-component, liquid-applied polyurethane waterproofing membrane — highly elastic, cold-applied, and self-curing. Built on pure elastomeric, hydrophobic polyurethane resins with excellent mechanical, chemical, thermal and weathering resistance. Recommended for wet areas and under-tile applications in kitchens, bathrooms, balconies, terraces and walls, as well as power houses, water-retaining structures and reservoirs. (Formerly known as ROOFCOAT PU 400.)
Specifications
Figures are controlled laboratory results. Actual site performance varies with substrate, temperature, humidity, application method and workmanship — please confirm the current product datasheet before specification.
Where to use RAINPROOF PU 400: polyurethane waterproofing membrane for wet areas and terraces
RAINPROOF PU 400 is a polyurethane waterproofing membrane that is single-component, liquid-applied, cold-applied and self-curing. It is highly elastic and has mechanical, chemical, thermal and weathering resistance. This liquid applied PU membrane is put down by roller in two or three layers, and is recommended for wet areas and under-tile work.
Kitchens & Bathrooms (Under-Tile)
Recommended under tiles in wet areas, applied in 2–3 layers.
Balconies & Terraces
Highly elastic membrane with a Solar Reflectance Index of 106.
Walls
Roller-applied liquid membrane with adhesion above 2.0 N/mm².
Power Houses
Recommended for power houses, with temperature resistance of -25°C to +90°C.
Water-Retaining Structures & Reservoirs
Water impermeability of 5 atm suits water-retaining structures.
Concrete, Metal, Wood & Tile Substrates
Cold-applied and self-curing on each of these listed substrates.
For bathroom floor leakage or an open terrace, consumption is 1.2–1.5 kg/m² in 2–3 layers. Elongation at break is 700% ± 50, tensile strength 4.8 N/mm², adhesion above 2.0 N/mm² and Shore A hardness 80 ± 2. Water impermeability is 5 atm. For EN 1504-2 waterproofing specifications, it also lists EN 1062-3 and DIN 1048. Apply by roller on a smooth surface, and note that temperature and application method can alter consumption.
Armstrong Chemicals supplies RAINPROOF PU 400 to sites across Telangana, Andhra Pradesh, Karnataka, Kerala and Tamil Nadu, including Hyderabad, Vijayawada, Bengaluru, Kochi and Chennai.
Waterproofing Built to Hold Water Back, Permanently
A single-component polyurethane membrane engineered to European standards — 700% elongation, SRI 106 solar reflectance, and 5 atm water impermeability for under-tile wet areas, reservoirs and water-retaining structures.
Get a QuoteWhy Standard Coatings Fail Under Tile & Submersion
Many waterproofing coatings aren't built for constant water pressure, under-tile bonding, or extreme temperature swings — they fail exactly where reservoirs, wet areas and water tanks need them most.
The RAINPROOF PU 400 Advantage
A polyurethane membrane tested to EN 1504-2 requirements, with 5 atm water impermeability, 700% elongation, and a -25°C to +90°C service range — built for the toughest water-retaining applications.
Engineered to European Standards
Complies with ASTM D-6083-97a and EN 1062-3, meeting EN 1504-2 requirements — independently tested for water vapour permeability, CO₂ permeability, adhesion, and capillary absorption.
Built for Water-Retaining Structures
5 atm water impermeability (DIN 1048) and zero-rated fungal resistance suit it to reservoirs, power houses and water tanks, not just roofs.
Choose Your Application System
Surface Preparation
Get the substrate sound, dry and within the required strength limits before any coating goes down.
Built to European Standards
Independently tested to international standards, for the jobs that can't afford a failure.
700% Elongation & Crack Bridging
Excellent crack-bridging with 700% ± 50 elongation at break and 4.8 N/mm² tensile strength, forming a seamless membrane with no joints or leak points.
Solar Reflective & Walkable
SRI 106 keeps surfaces cool and colour-stable; cures to a finish that can be walked on directly and resists frost.
5 ATM Water Impermeability
Tested to DIN 1048 for water-retaining structures, with non-toxic, zero-rated fungal resistance (ASTM G21-96).
Engineered to EU Standards
Complies with ASTM D-6083-97a and EN 1062-3, meeting EN 1504-2 requirements, with fire resistance to EN 12501-1.
Applicable Areas
Packing & Storage
Available in 1, 5, 10, 20 & 210 Litre packs. Shelf life of 2 years from manufacture date.
Critical Surface Requirements
Moisture content must not exceed 5%. Substrate compressive strength ≥ 25 MPa, cohesive bond strength ≥ 15 MPa. New concrete must cure 28 days minimum. Do not wash the surface with water before coating application.
Companion Products
Used alongside ROOFSEAL PS / ROOFSEAL PU, RAINSEAL BXL, WONDERSEAL XL / WONDERSEAL POWDER, ROOFCARE EP, ROOFCRETE AR, RAINPROOF PU 400 PRIME, and FLEXI backing rod, depending on the repair or application system.
Coverage Calculator
Coverage estimation is not applicable for this product. Please contact our team for application guidance.
Product Brochure
Download Technical Datasheet
Full specifications, application systems, layering guides, and coverage tables.
Frequently Asked Questions
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