Product Manuals
Introduction
Polyurethane membranes are elastomeric, liquid-applied systems that cure to form a seamless, monolithic waterproofing layer. Families range from water-based 1K hybrids to 2K hand- or spray-applied membranes. Selection depends on access, exposure to water and chemicals, expected crack movement, and execution speed.
Advantages
- Seamless and fully bonded layer reduces leak paths
- High elongation and crack-bridging capability
- Compatible with complex details and penetrations
- Broad chemistry range enables tuning for UV, traffic, and chemical resistance
- Rapid build possible with 2K spray systems on large areas
Limitations
- Substrate moisture can inhibit 1K moisture-cure grades
- 2K systems require strict A:B ratio control and trained crews
- Exposed systems may need wear coats or UV-stable topcoats
- Plant and PPE requirements for isocyanate-containing systems
Types
- Pitch-modified PU (1K)
- Water-based PU or PU-acrylic hybrids (1K)
- Pure PU (1K moisture cure)
- 2K PU (hand-applied)
- 2K PU (spray-applied)
- Hybrid PU blends and PRPU variants
- Polyurea (related, for comparison)
Application / Method Statement (Summary)
- Surface preparation: Cure concrete as specified, remove laitance and contaminants. Verify pull-off strength ≥ 1.0–1.5 MPa for demanding systems.
- Priming: Use manufacturer-recommended primer to enhance adhesion and reduce pinholes.
- Mixing and equipment: Maintain correct ratios for 2K systems. Use plural-component heated spray rigs for spray-applied PU.
- Thickness and coats: Build in multiple passes within recoat windows. Measure wet and dry film thickness.
- Curing and protection: Protect from rain/dew until cured. Provide wear coats or protection layers where required.
- Health and safety: Follow MSDS. Provide ventilation and respiratory protection for isocyanate systems.
Decision Guide
- Dynamic cracks or high movement joints → 2K spray PU or elastomeric 1K with proven crack-bridging
- Prolonged ponding or frequent wetting → 2K spray PU or robust 2K hand-applied systems
- Low-VOC, exposed roof coatings → water-based PU or PU-acrylic hybrids
- Chemical splash zones or STPs → pitch-modified PU or robust 2K systems after compatibility checks
- Small, detailed areas with intermittent exposure → 1K moisture-cure PU
Acceptance criteria
Surface preparation verified. Substrate sound, clean, and within moisture limits as applicable.
Adhesion test (pull-off) meets requirement. Target ≥ 1.0–1.5 MPa for demanding PU systems.
Wet film thickness and dry film thickness recorded per coat. Final DFT meets specification.
Recoat windows respected and curing conditions maintained.
Protection or wear coats applied where specified. Details at upstands and penetrations complete.
QA records captured. WFT/DFT logs, adhesion tests, batch numbers, photographs.
Video
SpecX Masterclass: Polyurethane Membranes — Coming soon
Disclaimer
SpecX is an industry initiative and a neutral resource, compiled from industry references and best practices. It is not brand-specific. Always cross-check with project requirements and local codes before finalizing specifications.