Air & vapor barriers
Exterior fluid-applied air and vapor barriers that control air leakage and moisture movement through the building envelope.
Air leaking through a wall assembly carries moisture with it, and that moisture is what drives mold, rot, and energy loss. A fluid-applied air and vapor barrier is sprayed or rolled onto the exterior sheathing as a liquid, curing into a continuous membrane that seals the envelope at seams, corners, and penetrations that a sheet or tape system has to be cut and lapped around.
Which control does your assembly need?
The right system depends on climate and how tightly the wall assembly is built.
| Attribute | Air barrier only | Air + vapor barrier |
|---|---|---|
| Stops air leakage | Yes | Yes |
| Controls vapor diffusion | No | Yes |
| Best for | Vented or mixed assemblies | Cold-climate, tight assemblies |
| Application | Fluid-applied, exterior | Fluid-applied, exterior |
What a continuous barrier controls
Air leakage
Uncontrolled air movement through a wall assembly wastes energy and carries moisture into the wall cavity. A continuous barrier stops it at the source.
Moisture control
Vapor-permeance class is matched to the climate and assembly, controlling condensation without trapping moisture that needs to dry.
Energy performance
Sealing air leakage reduces the load on heating and cooling systems, since conditioned air is no longer escaping through the envelope.
Seamless application
Fluid-applied membranes seal seams, corners, and penetrations continuously, without the laps and tape joints a sheet system requires.
Air and vapor barrier questions
What is an air and vapor barrier?
An exterior fluid-applied membrane that controls air leakage and moisture movement through the building envelope, improving energy performance and protecting the wall assembly.
Do I need an air barrier, a vapor barrier, or both?
It depends on the climate and wall assembly. Cold-climate, tightly built assemblies commonly need both air and vapor control; vented or mixed assemblies may only need an air barrier. We confirm the right system for the building.
What surfaces does this apply to?
Exterior sheathing on commercial building envelopes, applied before the exterior cladding or insulation goes on.
How is this different from a sheet or tape air barrier?
A fluid-applied system cures into one continuous membrane with no seams or laps to fail, sealing corners and penetrations that a sheet system has to be cut and taped around.
Is this self-performed or through a partner?
Air and vapor barriers are delivered in-house or with a specialty partner depending on the project.
Is this an established service or a new one?
It's part of A-1's growing specialty coatings line, applying the same fluid-applied chemistry used on roofs to the building envelope. We're upfront that it's a building capability rather than a long project history.
Related services
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- PROProtective Tank & Wall CoatingsFluid-applied protective coatings for tanks, vessels, and commercial walls: chemical, abrasion, and weather resistance in one continuous membrane.
- PEDPedestrian & Traffic CoatingsWalkable, waterproof fluid-applied coatings for parking garage decks, plazas, and walkways, protecting the structure below while carrying traffic.
Building an envelope that needs air and moisture control?
Tell us the climate and assembly, and we will tell you honestly which barrier system fits.
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