Advantages and Considerations of Liquid-Applied Air Barrier Membranes

Like all air barrier systems and solutions, a liquid-applied air barrier membrane controls the flow of air and moisture into and out of a building. In so doing, a liquid-applied air barrier provides several benefits, from reducing building energy consumption and condensation in the wall assembly to protecting building integrity and the comfort and safety of its occupants.

Liquid-applied air barrier advantages

Liquid-applied air barrier membranes can be spray-, roller-, or trowel-applied over a wide range of substrates. Unlike self-adhered sheet applied air barrier systems, liquid-applied air barriers provide a monolithic membrane with no seams. This makes liquid-applied membranes ideal for easy installation on large buildings with complex geometries and pronounced angle changes, or multi-plane construction conditions and veneer anchors.

While liquid-applied membranes are suitable for use over a range of substrates – including OSB, plywood and gypsum – they are particularly well suited for rough or irregular surfaces such as CMU and prepared concrete.

Whatever the substrate material, liquid-applied air barrier membranes generally enable an easier and faster installation vs. self-adhered sheet applied air barrier systems. Often, liquid-applied membranes are spray-applied, which can help keep even the largest building projects on track, or even ahead of schedule. In part, that’s also because many of today’s liquid-applied air barriers are formulated with rapid cure times that allow them to cure in an hour or less, and resist wash-off if the forecast says rain is possible.

Liquid-applied air barrier considerations

Installation issues
Unlike self-adhered sheet applied air barrier membranes, the application thickness of a liquid-applied air barrier membrane is entirely dependent on the installer and installation equipment.

For example – although air barrier manufacturers provide mil gauges to help contractors achieve the required material thickness, meeting these requirements is ultimately tied to the skill and experience of the installer. Spray equipment operators must also take care not to overspray onto nearby surfaces.

Air barrier system selection
Making sure that a liquid-applied air barrier membrane is your optimal choice will speed construction, cut costs and help protect the health of the building and its occupants. When choosing between a liquid-applied and a sheet-applied self-adhered membrane, there are several things to consider beyond the substrate surface and complex geometries. These include:

• Climate zone – What climate zone will the air barrier system be functioning in? Each zone has its own unique conditions and challenges that must be weighed carefully.
• Wall assembly design – Again, beyond the substrate surface, other aspects of the wall assembly design must be considered. What are the related building performance requirements? Which air barrier type will best prevent condensation in the wall assembly? Does it need to be NFPA-compliant? All of these factors matter.
• Vapor permeable or non-permeable – Climate zone and wall assembly design will both help determine whether to go with a vapor impermeable or a non-permeable air barrier.

Is a liquid-applied barrier right for your project?

At Henry® Company, we’ve been helping to manage the flow of water, air and vapor throughout the building envelope for 80+ years. Our building envelope experts can help you weigh the pros and cons of different liquid-applied air barrier membranes or self-adhered air barrier membranes for your next build.