PENNSYLVANIA · PHILADELPHIA
Where two rivers meet the wind: Philadelphia's nor'easter-tuned loads
From the Delaware River wharves to Center City's high-rises, Philadelphia County designs to a 110-120 mph map under ASCE 7-22 and the Philadelphia Building Code.
DELAWARE & SCHUYLKILL · WIND PROFILE
How a mid-Atlantic city splits its wind exposure
Open river fetch on the east, dense rowhomes and towers inland — two terrains, one permit set.
Buildings within roughly 1,000-2,000 ft of the Delaware River face open water fetch and read Exposure C; the rowhome grid and high-rise canyons of Center City shelter to Exposure B.
WHY 110-120 MPH
Nor'easters, remnant hurricanes & a river that won't hold still
Philadelphia's hazard is long-duration coastal lows, not the brief gust fronts of the interior — plus tropical remnants that flood the valley.
Nor'easter loading
Coastal lows drive 12-36+ hours of sustained wind, prolonged pressure on roofs and facades.
PRIMARY THREATTropical remnants
Floyd, Irene, Sandy & Isaias arrived weakened but still gusted past 70 mph; Ida's 2021 remnants brought historic valley flooding.
REMNANT + FLOODRowhomes to towers
Unreinforced masonry blocks and Center City high-rises load very differently — height-varying Kz matters.
EXPOSURE BRiver fetch
Open Delaware water gives long unobstructed fetch, pushing waterfront sites to Exposure C and 115-120 mph.
EXPOSURE CASCE 7-22 · TABLE 1.5-1
Risk category drives the Philadelphia speed map you read
Higher risk category means a longer-return-period map and a higher design speed — not a fixed multiplier.
| Risk Category | Philadelphia Design Wind Speed | Building Types |
|---|---|---|
| Risk Category I | ~105-115 mph | Agricultural facilities, temporary structures, minor storage |
| Risk Category II | 110-120 mph | Residential, commercial, hotels, most standard occupancies (apartments, offices) |
| Risk Category III | ~125-135 mph | Schools, assembly >300, substantial hazardous materials |
| Risk Category IV | ~135-145 mph | Hospitals, fire stations, emergency shelters, essential facilities |
PHILADELPHIA COUNTY · COMPLIANCE
What L&I expects in a Philadelphia permit set
PE-sealed ASCE 7-22 calculations, exposure justification, and historic review where it applies.
Building code
Philadelphia Building Code adopts the IBC with local amendments, referencing ASCE 7-22 for wind.
PHILA BUILDING CODEPE seal required
All structural calculations must be sealed by a Professional Engineer licensed in Pennsylvania.
PA PEeCLIPSE submittal
Philadelphia L&I reviews permits and plans through the online eCLIPSE portal.
L&I AHJHistoric review
Old City, Society Hill and other districts trigger Philadelphia Historical Commission approval.
PHCC&C + MWFRS
Sealed sets must include component & cladding and main wind-force pressures per ASCE 7-22.
FULL PRESSURE SETWaterfront + flood
Delaware River sites combine Exposure C wind with flood loading — document both hazards.
COMBINED HAZARD19100-19154 · BY NEIGHBORHOOD
Wind speed shifts block by block across Philadelphia
Interior neighborhoods read Exposure B near 110-115 mph; riverfront zips climb to Exposure C and 115-120 mph.
19102-19107 · Center City
110-115 mph, Exposure B — dense high-rise sheltering.
EXP B19106 · Old City
110-115 mph, Exposure B — historic preservation applies.
HISTORIC19104 · University City
110-115 mph, Exposure B — dense institutional grid.
EXP B19123 · Northern Liberties
110-120 mph, B interior or C at the riverfront.
B / C19148 · South Philly Waterfront
115-120 mph, Exposure C near the Delaware River.
EXP C19135 · Port Richmond
115-120 mph, Exposure C — northeast riverfront.
EXP CThe WindLoadCalc.com calculator resolves the exact velocity and exposure from any Philadelphia zip or address.
VELOCITY PRESSURE · ASCE 7-22
A riverfront example, worked to qz
qz = 0.00256 · Kz · Kzt · Kd · Ke · V²
A Northern Liberties waterfront roof at this velocity carries substantial uplift — Center City Exposure B sites at 110 mph ease off but stay significant as Kz climbs with height.
PENNSYLVANIA · STATEWIDE
Compare Philadelphia against the wider wind map
Step out from Philadelphia County to statewide adoption and location-based speeds.
OFFICIAL PHILADELPHIA RESOURCES
Authoritative sources for Philadelphia compliance
AUTOMATE PHILADELPHIA WIND LOADS
From the Delaware to Center City, calculated in minutes
Enter any Philadelphia address for ASCE 7-22 velocities (110-120 mph), B/C exposure guidance, risk-category adjustment, and PE-ready reports for L&I submission.