Liquid Applied Membrane
Liquid applied membrane roofing systems are seamless, monolithic coverings created by applying liquid resin or polymer materials that cure in place to form a continuous, flexible waterproofing layer. These versatile systems can be applied to complex geometries and existing substrates, providing solutions for new construction, restoration, and challenging waterproofing applications where conventional sheet membranes would be difficult to implement.
Composition
Specialized material designed for weather protection and durability on building roofs
Properties
Elongation
100-900%
Elongation capacity varies significantly by chemistry. Acrylic systems typically offer 100-300% elongation, polyurethanes 200-450%, silicones 150-400%, and polyureas can reach 300-900%. This property determines the membrane's ability to accommodate building movement and thermal cycling without cracking or splitting.
Tensile Strength
200-4000 psi
Tensile strength varies by chemistry and reinforcement. Acrylics typically range from 200-400 psi, polyurethanes 800-2500 psi, silicones 300-550 psi, and polyureas 1500-4000 psi. Reinforced systems achieve higher tensile strength, particularly important at seams, transitions, and areas subject to mechanical stress.
Thickness
30-100 mils (0.030"-0.100")
Applied thickness varies by system type and performance requirements. Maintenance coatings may be as thin as 15-20 mils, while primary waterproofing systems typically range from 30-100 mils. Reinforced areas and high-traffic zones often receive additional material to enhance durability and puncture resistance.
Weight
0.3-0.8 lbs/ft²
Significantly lighter than many conventional roofing systems. Typical liquid applied systems weigh 0.3-0.8 lbs/ft² depending on thickness and formulation, making them suitable for structures with limited load-bearing capacity and ideal for retrofit applications without adding significant weight.
Solar Reflectance Index (SRI)
White: 90-110, Colored: 20-85
Solar reflectance varies significantly by color and formulation. White or light-colored systems typically achieve SRI values of 90-110, exceeding ENERGY STAR and cool roof requirements. Colored formulations range from 20-85 depending on pigmentation. High SRI values reduce solar heat gain and urban heat island effects while potentially lowering cooling energy consumption.
VOC Content
0-450 g/L
Volatile Organic Compound (VOC) content varies significantly by chemistry. Water-based acrylics typically contain 0-50 g/L, while solvent-based polyurethanes may contain 100-450 g/L. Low-VOC and zero-VOC formulations are increasingly available to meet environmental regulations and green building requirements.
Applications
Complex Roof Geometries
Ideal for roofs with numerous penetrations, irregular shapes, or complex details where sheet membranes would require extensive cutting, fitting, and seaming. The liquid nature allows the material to conform to virtually any geometry, creating a seamless, monolithic covering even around challenging details.
Roof Restoration
Widely used for restoring and extending the service life of existing roofing systems including built-up roofing, modified bitumen, single-ply membranes, metal roofing, and spray polyurethane foam. This restoration approach can provide 10-20+ additional years of service while avoiding costly tear-off and replacement.
Green Roof Waterproofing
Excellent primary waterproofing layer beneath green roof assemblies due to seamless nature, root resistance (with appropriate additives), and ability to conform to irregular substrates. The monolithic application eliminates the seams and joints that are vulnerable points in traditional membrane systems.
Plaza Decks and Vegetated Areas
Applied in horizontal applications where waterproofing will be covered with pavers, concrete, or landscaping. The seamless nature and ability to integrate with drainage components make these systems ideal for occupied roof decks, terraces, and amenity spaces.
Solar Integration
Used as waterproofing beneath solar panel arrays, particularly ballasted systems where roof penetrations must be minimized. The reflective nature of white coatings can enhance solar panel efficiency by reducing ambient roof temperatures and increasing reflected light.
Limited Access Areas
Suitable for roofs with limited accessibility where future repairs would be challenging or disruptive. The monolithic nature eliminates the most common failure points (seams) and many systems can be recoated at the end of their service life without removal, extending performance indefinitely with proper maintenance.
Advantages
- Seamless, monolithic coverage eliminating the most common failure points
- Ability to conform to irregular shapes and complex geometries
- Excellent for integrating with penetrations, curbs, and transitions
- Can be applied over many existing roofing systems without tear-off
- Lightweight nature ideal for structures with limited load capacity
- High solar reflectivity reducing cooling loads (with light colors)
- Self-flashing capability simplifying details and transitions
- Renewable through recoating at end of service life
- Excellent resistance to ponding water with appropriate formulations
Limitations
- Application quality highly dependent on installer expertise
- Sensitivity to substrate preparation and environmental conditions
- Potential for pinholing and thickness inconsistencies
- Some formulations have significant odor and VOC content
- Limited application windows for weather-sensitive formulations
- Cure time vulnerability to weather events for some systems
- Higher initial cost compared to conventional single-ply membranes
- Challenging quality control for thickness and coverage
- Some formulations have limited low-temperature flexibility
Sustainability Profile
Sustainable roofing options include recycled materials, cool roofs that reduce energy consumption, and living roofs that provide insulation and manage stormwater. Durability is a key factor in sustainability assessment.