Materials for Urethane
Urethane waterproofing coatings come in two main forms: two component systems and moisture curing formulations. Two component systems provide precise film thickness and strong elongation resistance, while moisture curing versions simplify on site mixing. For rooftop and exterior wall applications, prioritize products with proven UV stability and weather resistance. If the coating will be in contact with potable water or nearby water supply piping, select formulations approved for drinking-water contact and ensure proper curing before exposure.
Choose material grades based on exposure and substrate compatibility, including concrete, metal, or masonry. Low VOC or solvent free options reduce indoor odor and emissions during application. When the system surrounds water supply piping or is used on bathrooms, prefer potable-water contact approved coatings and ensure compatibility with sealants and gaskets. Plan a full cure cycle and verify with a water resistance test before returning service.
Surface prep and adhesion
Successful adhesion starts with thorough surface preparation. Clean, dry substrates free of laitance and oil yield better bonding and film uniformity. Roughening the surface with mechanical abrasion improves mechanical interlock and reduces dust. Repair any cracks or voids before coating to prevent later delamination.
Primer selection should match the urethane system and substrate. Check humidity and dew point to avoid premature film formation. Apply primer evenly and allow the recommended cure time before applying the main coat. Ensure compatibility with future topcoats and joint details around water service penetrations.
Application and cures
Apply by spray, roller, or squeegee depending on the surface and system. Thickness targets typically range from 1.5 to 2.5 millimeters per layer, with multi-layer builds for reinforced regions. Reinforcement fabrics or meshes may be embedded at joints and penetrations to improve tear resistance. Always follow the manufacturer's recoat window to ensure uninterrupted film continuity.
Curing depends on temperature, humidity, and substrate moisture. Plan the work for dry conditions. After application, avoid standing water until the film reaches its rated hardness. Seal around penetrations such as water supply pipes and drains with compatible sealants. Consider future maintenance access and ensure the coating remains accessible for inspections.
Maintenance tips
Schedule regular inspections after heavy rain or freeze-thaw cycles. Look for blisters, cracks, or delamination and address issues promptly. Clean surfaces lightly to remove dirt that can harbor moisture and hide defects. Plan proactive recoat cycles based on UV exposure and wear patterns.
Use patch kits for small imperfections, ensuring the patches bond to the cured film. Top coats with UV protection help extend service life, especially on sun-exposed roofs. Document maintenance milestones and water-test critical areas to protect potable water zones. Emerging trends include low-VOC formulations, fabric-reinforced systems, and self-healing polymers for longer intervals between inspections.