What Is Curtain Wall Pressure Equalization?
Pressure equalization designs the curtain wall's rainscreen so the air pressure inside the glazing cavity equals the outside — eliminating the pressure difference that drives the rainwater inward. The wall's outer skin (the rainscreen) sheds the bulk water; the equalized cavity (the pressure-equalized chamber) stops the wind-driven remainder; the inner seal (the air/water barrier) is the final defense. The physics making the modern curtain wall weathertight.
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How pressure equalization works
The compartments (the cavity divided into the pressure-equalized chambers — the vertical and the horizontal divisions; each chamber vented to the exterior — the vents sized for the rapid equalization), the rainscreen (the outer glazing or the panels — the water-shedding; the joints — the baffled, not the sealed), and the air seal (the inner line — the continuous air barrier; the water's final stop). The wind's pressure (the gusts — the cavity's pressure tracking the exterior's; the no-differential — the water not driven inward).
Design details
The venting (the vent area — the 1-2% of the chamber's face typical; the vent locations — the top and the bottom; the baffles — the water's exclusion while the air passes), the compartmentalization (the chamber sizes — the smaller chambers equalizing faster; the sealants dividing), and the testing (the AAMA 501.1 water — the static; the 501.1 dynamic — the wind-driven; the mockup — the performance verified). The drained vs. the pressure-equalized (the evolutionary steps — the weeped, the drained, the equalized).
Failures and verification
The blocked vents (the construction debris — the equalization defeated; the maintenance — the vents kept clear), the uncompartmentalized (the large cavity — the slow equalization; the wind's pumping), and the air-seal breaches (the inner line's discontinuity — the water's path). The field testing (the AAMA 503 — the installed wall's water testing; the hose test — the workmanship verified). The pressure-equalized wall is the standard for the high-performance curtain wall — the physics, not the sealant, keeping the water out.
The bottom line
Pressure-equalized curtain walls vent cavity chambers to the exterior, eliminating the pressure driving rain inward — compartmentalize, vent adequately, maintain the inner air seal, and field-test per AAMA 503.
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