What Is a Liquid Applied Weather Resistant Barrier?
A liquid-applied weather resistant barrier (LAWRB) is a fluid-grade coating that is sprayed, rolled, or troweled onto the exterior sheathing and cures to form a seamless, monolithic waterproof membrane. Unlike sheet-based WRBs that are lapped and taped, liquid-applied systems eliminate all seams — creating a truly continuous air and water barrier around the entire building envelope.
Exteriors Design LLC installs liquid-applied WRB systems on commercial and multi-family projects across Portland, OR. These systems are particularly valuable on buildings with complex geometries, numerous penetrations, or aggressive energy code requirements where seam-free performance is critical.
How Liquid Applied WRB Installation Works
Surface preparation is the most critical step in liquid-applied WRB installation. All sheathing must be clean, dry, and free of contaminants. Gaps, fastener heads, and sheathing joints are detailed with bridging membrane or backer rod before the primary coat is applied. The LAWRB is then applied by spray or roller in 2-3 coats to achieve the required dry film thickness, typically 20-40 mils depending on the product and exposure conditions.
Around window and door rough openings, the liquid membrane is applied directly over the opening corners and up into the rough opening — eliminating the most common leak locations in conventional WRB systems. All utility penetrations are sleeved and coated in a single continuous operation.
Benefits of Liquid Applied WRB Systems
- Zero seams: A truly monolithic membrane with no laps, seams, or mechanical fasteners
- Complex geometry compatibility: Conforms to any shape — corners, curves, reveals, and penetrations are all seamlessly waterproofed
- Superior air barrier performance: Liquid-applied systems routinely achieve the lowest air leakage rates of any WRB type
- Faster penetration detailing: All penetrations are integrated into the primary membrane application — no separate flashing tapes required
- Compatible with continuous insulation: Works with CI exterior insulation board systems required by Oregon's energy code
Ideal Applications
Liquid-applied WRBs are ideal for Type I concrete and masonry construction, buildings targeting passive house or high-performance certifications (LEED, Phius), projects with aggressive air leakage requirements (ACH50 < 3.0), complex architectural buildings with many penetrations and reveals, and renovation projects where integrating a sheet WRB with existing conditions is difficult.
Products We Install
We install Stoguard (STO Corp), Prosoco R-Guard (Prosoco), and AirBlock (Henry) — all vapor-permeable liquid-applied WRBs with strong Pacific Northwest track records. Contact our team at (503) 914-0200 or get a free estimate for your project.