Commercial air barrier systems – considerations for success
To perform as effectively as possible, a commercial air barrier system has to do several jobs at once. These performance requirements include:
- Protecting against unwanted air and moisture intrusion
- Meeting current building codes and environmental regulations
- Delivering effective fire protection as part of the wall assembly
- Helping satisfying energy efficiency requirements
- Acting as the second line of defense – behind the cladding – to keep bulk water out
Designing, specifying and installing an air barrier system that does all of the above can be a complex challenge. Fortunately, keeping the following factors in mind can make it much simpler. Here are some key air barrier system considerations for success:
Know your climate zone
Air and vapor barrier system design must take the climate zone into account. Climate conditions most directly impact moisture mitigation and energy efficiency, but each of the following 7 zones presents unique challenges to air and vapor barrier performance:
Wall assembly design
Considering how the air barrier system will interact with the wall assembly is also essential.
- What is the substrate onto which the air barrier will be applied?
- Are there any complex design details, geometries, or rough surfaces?
- Where is the insulation located?
- What about compliance with NFPA 285?
Answering these questions up front will help avoid issues later.
Vapor impermeable or permeable?
Vapor impermeable air barriers act as air, vapor and bulk water barriers. When positioned on the warm side of the insulating layer, they prevent moisture condensation through the wall cavity. Vapor permeable air barriers also act as air and bulk water barriers, but allow moisture vapor to pass through them. Typically, they can be positioned anywhere in the wall assembly.
Self-adhered sheet or fluid-applied?
Commercial air barrier membranes are available in two main types: self-adhered sheet and fluid-applied. Depending on project requirements, each has its own pros and cons.
With self-adhered sheet air barriers, the manufacturer controls the membrane thickness. No mixing or special installation equipment is required, and the sheets easily bridge gaps. Fluid-applied air barriers provide a seamless, monolithic membrane that seals easily around penetrations and is well suited for complex geometries and rough surfaces.
Both self-adhered and fluid-applied membranes must be paired with the right primers, flashings and sealants to complete the system.
Look to Henry for help
It’s a lot to consider, which is why architects, building envelope consultants and contractors often turn to Henry for guidance. Informed by 80+ years of Henry building envelope expertise, our building envelope experts can help you select an air barrier system that best meets your project requirements.
Need help choosing the right air barrier system?