DISTRICT OF COLUMBIA · FEDERAL DISTRICT
Wind Loads on the Potomac: Engineering the Federal Capital
No state, no county lines — a federal district on the fall line of the Potomac, where DC Construction Codes meet ASCE 7-22 and a memory of derecho winds.
POTOMAC EXPOSURE · TIDEWATER MEETS URBAN CANYON
Why the Capital's Wind Map Reads 110–120 mph
The District sits inland of the coast but open to the mid-Atlantic — the speed you design to swings with how exposed your block is to the river.
Riverfront, Exposure C
Georgetown Waterfront, The Wharf, Navy Yard and the Anacostia edge see open water — the higher end of the band, roughly 115–120 mph.
EXPOSURE CDowntown Canyons, Exposure B
The Federal Triangle, Capitol Hill, Dupont and Adams Morgan shelter each other — the lower band near 110–115 mph under Exposure B.
EXPOSURE BPalisades & Rock Creek Terrain
Elevated ground along the Potomac Palisades and the Rock Creek valley can lift the topographic factor Kzt above 1.0 near a crest, returning to 1.0 away from it.
Kzt > 1.0 LOCALLYStorm memory shapes the map: remnant hurricanes such as Isabel (2003) tracking up the Chesapeake, and the fast-moving June 2012 derecho that raked the metro with 60–80 mph straight-line gusts. Exact mph is site-specific — the map varies by quadrant and exposure.
PERMIT READINESS · DC DEPARTMENT OF BUILDINGS
What a District Submittal Has to Show
Sealed by a PE licensed in the District, every set carries the same load-path proof.
ASCE 7-22 Wind Speed
Site V from the current maps — 110–120 mph for Risk Cat II, higher for III and IV.
ASCE 7-22Exposure Justification
B for the urban core, C for the Potomac and Anacostia waterfronts — with supporting terrain reasoning.
B / CHeight Act Compliance
The 1910 Height Act caps most structures near the street-width-plus-20 rule, holding the skyline to mid-rise.
HEIGHT ACT 1910MWFRS + C&C Pressures
Main-frame and component pressures for cladding, windows and roof — with HPO coordination in historic districts.
MWFRS · C&CRISK CATEGORY · LONGER RETURN PERIOD, FASTER MAP
How Occupancy Lifts the Design Speed
In ASCE 7-22 the risk category picks a different speed map — a longer return period, not a multiplier.
| Risk Category | Map (MRI) | Typical District Buildings |
|---|---|---|
| I | 300-year | Minor storage, agricultural-type, temporary structures |
| II | 700-year | Rowhouses, apartments, offices, hotels — the 110–120 mph band |
| III | 1,700-year | Schools, large assembly, substantial-hazard occupancies |
| IV | 3,000-year | Hospitals, fire and police, emergency shelters and EOCs |
ACROSS THE BELTWAY · OFFICIAL DISTRICT SOURCES
Look Up a Neighboring Jurisdiction
The District is ringed by Maryland and Virginia codes — and four District offices govern the work inside it.
State & District Requirements
Compare adopted codes and ASCE editions nationwide.
DIRECTORYWind Speed by Location
Find the design speed for any address or ZIP.
LOOKUPASCE 7 Standards
The methodology behind every District calculation.
STANDARDDC Department of Buildings
The District's authority having jurisdiction.
AHJDC Construction Codes
IBC adopted with District-specific amendments.
CODEHistoric Preservation Office
Review for projects inside District historic districts.
HPOASCE 7-22 · DC CONSTRUCTION CODES
Calculate Capital Wind Loads in Minutes, Not Days
Enter a District address and get site speed, B-or-C exposure, risk-category pressures and a PE-ready report for the DC Department of Buildings.