Complete Door Frame Height Chart & Buying Guide: Standard Sizes, Casing Types, and Custom Fits
By Alexander Ross
Commercial buildings and accessible residential spaces must comply with federal accessibility standards. Under the Americans with Disabilities Act (ADA) Section 404.2.3, doorway openings must maintain a minimum clear opening height of 80 inches from the finished floor surface to the bottom of the door stop or head jamb.
While standard residential construction allows the door stop to hang slightly below 80 inches, commercial ADA paths of travel view this as an obstruction. Protruding objects along accessible circulation routes cannot hang lower than 80 inches if they narrow the clear headroom.
Sills and thresholds trigger strict scrutiny under ADA regulations:
- Maximum threshold height for standard exterior doors is 1/2 inch.
- Existing facilities undergoing alterations allow up to 3/4 inch if the threshold features a beveled edge with a slope no steeper than 1:2.
- Any threshold higher than 1/4 inch must be beveled at a 1:2 slope to permit wheelchair wheels to pass smoothly without jarring impact.
These constraints influence the exterior door jamb height. Because the exterior sill cannot sit high off the finished floor, rough sill framing must stay flat, flush, and level across the entire entryway. Any tilt in the rough floor telegraphs directly into the threshold, creating an out-of-spec bump that fails municipal code inspections.
Alexander Ross has covered the video game industry for a decade, writing deep dives on game design, esports tournaments, VR developments, and gaming culture.
