ASCE 7-22 · FIG 30.3-1 · COMPONENTS & CLADDING
Wind Loads on Windows & Doors
Glazing and openings are Components & Cladding. They see higher local pressures than the building frame — especially at the corners.
WALL ZONES · ELEVATION
Field vs corner openings
On a wall, openings in the corner strips (Zone 5) carry higher suction than those in the interior field (Zone 4).
Same wind speed, same wall — a corner window must be rated for a higher suction than an identical window in the field.
ASCE 7-22 FIG 30.3-1 · WALL C&C · h ≤ 60 ft
Pressure coefficient by zone
External pressure coefficients (GCp) for wall openings, anchored at 10 and 500 sq ft of effective wind area.
| Zone | Location | GCp @ 10 sq ft | GCp @ 500 sq ft |
|---|---|---|---|
| Zone 4 | Interior wall (field) | −1.1 | −0.8 |
| Zone 5 | Corner wall | −1.4 | −0.8 |
| Zones 4 & 5 | Positive (inward) | +1.0 | +0.7 |
Zone 4 — Field
Interior wall suction: −1.1 at 10 sq ft easing to −0.8 at 500.
−1.1 → −0.8Zone 5 — Corner
Worst suction on the wall: −1.4 at 10 sq ft, the controlling case.
−1.4 → −0.8Positive (inward)
Both zones push inward: +1.0 at 10 sq ft down to +0.7 at 500.
+1.0 → +0.7Corner Zone 5 governs the negative (suction) design — size the worst opening on that case.
EFFECTIVE WIND AREA
Smaller area, higher coefficient
GCp is logarithmically interpolated by effective wind area. A small fixed window or a single door panel pulls the largest coefficient; a wide storefront or curtain-wall span averages down toward the 500 sq ft value.
Don't use a wall's average pressure to pick a single small opening — the smaller the tributary area, the higher the local GCp.
DESIGN PRESSURE · DP RATING
What a DP rating means
A window or door's Design Pressure is the wind load it is tested and certified to resist — positive and negative.
DP = qh ( GCp − GCpi )
where qh = 0.00256 · Kz · Kzt · Kd · Ke · V² and Kd = 0.85
Positive DP
Wind pushing the unit inward — built from the positive GCp (+1.0 to +0.7).
INWARDNegative DP
Suction pulling the unit outward — driven by Zone 5 corner GCp (−1.4).
OUTWARDEnclosed
Internal pressure GCpi of ±0.18 adds to the external coefficient.
GCₙₙ ±0.18Partially enclosed
A breached envelope swings GCpi to ±0.55, sharply raising DP.
GCₙₙ ±0.55The combination GCp − GCpi that produces the largest magnitude sets the rating you must meet. Select a unit whose tested DP is at least your computed design pressure.
KEEP GOING
Size every opening with confidence
Go deeper on glazing pressures, impact protection, and the full building envelope.