Door Rough Openings
Doors & Walls · 8 specs
Direct Answer
Door rough openings are standardized framing openings in wood and steel stud walls engineered to accept pre-hung door frames, shims, and finished jambs. Under standard architectural guidelines, rough opening width is calculated as Nominal Door Width + 2.0 inches, and rough opening height is calculated as Nominal Door Height + 2.5 inches, with standard 36×80" doors accommodating ADA accessibility.
Source: WDMA I.S. 1-A / ADA Standards for Accessible Design 2010 · Last reviewed Aug 28, 2026
Specs
| Governing Standards | WDMA I.S. 1-A / ANSI A250.8 / ADA Standards Section 404 |
| Rough Opening Width Formula | Nominal Door Width + 2.0 inches (51 mm) |
| Rough Opening Height Formula | Nominal Door Height + 2.5 inches (64 mm) |
| 30×80" Bedroom Door (2/6 × 6/8) | Rough Opening: 32.0 × 82.5 inches (813 × 2096 mm) |
| 32×80" Standard Entry (2/8 × 6/8) | Rough Opening: 34.0 × 82.5 inches (864 × 2096 mm) |
| 36×80" ADA Entry (3/0 × 6/8) | Rough Opening: 38.0 × 82.5 inches (965 × 2096 mm) |
| Standard 2×4 Wall Jamb Depth | 4-9/16 inches (116 mm) = 3.5" stud + two 1/2" drywall layers |
| Standard 2×6 Wall Jamb Depth | 6-9/16 inches (167 mm) = 5.5" stud + two 1/2" drywall layers |
The Universal Rough Opening Sizing Rule
When framing door openings with wood king and jack studs, carpenters utilize the universal rule of thumb: Rough Opening Width = Door Width + 2.0 inches Rough Opening Height = Door Height + 2.5 inches
This extra allowance provides:
- 1.50 inches for the two 3/4-inch solid wood side jambs.
- 0.50 inches of total side-to-side shim space (1/4 in per side) to plumb the jamb in imperfectly vertical stud walls.
- 2.50 inches in height to accommodate the 3/4-inch top head jamb, 1/2-inch top shim gap, and 1-1/4-inch floor clearance for carpet/hardwood.
ADA Accessibility Requirements (36-Inch Doors)
Section 404 of the ADA Standards for Accessible Design mandates a minimum clear opening width of 32.0 inches (813 mm) measured between the face of the door (open at 90°) and the opposing door stop. Because the door slab thickness (1-3/4 in) and hinge projection intrude into the opening, a 36-inch (3/0) door (rough opening 38× 82.5 in) is required to achieve full ADA legal compliance.