Why Integrated Louvers Fail Air and Water Tests

Put an integrated louver under a standard air and water test, and it fails almost every time. Here’s why.

Curtain Walls vs. Louvers: Two Different Design Philosophies

Curtain walls and windows are engineered as pressurized systems:

• Pressure-equalized chambers manage wind-driven rain.

• Continuous gaskets seal against infiltration.

• Drained weep paths redirect water out of the system.

The goal is simple: resist water penetration under pressure.

Louvers, however, are designed for an entirely different purpose:

• Angled blades deflect rainfall.

• Gravity and weep holes shed water away.

• They rely on shedding, not sealing.

Once you place a louver in a pressurized test chamber, water is forced past the blades. What works in natural rainfall doesn’t hold up under artificial test pressures.

The Fundamental Difference

• Windows/curtain walls = sealed, pressure-managed assemblies

• Louvers = open, water-shedding devices

This means most architectural louvers cannot be rated for air and water resistance the same way glass and framing can.

The Real Weather Barrier

If a louver is integrated into the façade, it should never be considered the primary line of defense. The true protection must come from:

• A secondary wall

• A drainage plane

• Or another backup system behind or around the louver

Bottom Line

Louvers serve an important role in ventilation and airflow, but they aren’t weather barriers. Expecting them to perform like windows under air and water testing is a misunderstanding of their function. The louver sheds — the wall behind it must protect.