Rough opening chart: finished opening, headroom & side room
One row per common size. The finished opening matches the door's nominal width and height exactly; headroom and side room are added on top, outside that framed opening.
| Door size | Finished rough opening (W × H) | Headroom — standard track | Headroom — low-headroom track | Side room (each side) |
|---|---|---|---|---|
| 8×7 | 8'0" × 7'0" | ≈ 10" | ≈ 4.5″–6.5″ | ≈ 3.75" |
| 9×7 | 9'0" × 7'0" | ≈ 10" | ≈ 4.5″–6.5″ | ≈ 3.75" |
| 9×8 | 9'0" × 8'0" | ≈ 10" | ≈ 4.5″–6.5″ | ≈ 3.75" |
| 10×7 | 10'0" × 7'0" | ≈ 10" | ≈ 4.5″–6.5″ | ≈ 3.75" |
| 10×8 | 10'0" × 8'0" | ≈ 10" | ≈ 4.5″–6.5″ | ≈ 3.75" |
| 12×7 | 12'0" × 7'0" | ≈ 10" | ≈ 4.5″–6.5″ | ≈ 3.75" |
| 14×7 | 14'0" × 7'0" | ≈ 10" | ≈ 4.5″–6.5″ | ≈ 3.75" |
| 16×7 | 16'0" × 7'0" | ≈ 10" | ≈ 4.5″–6.5″ | ≈ 3.75" |
| 16×8 | 16'0" × 8'0" | ≈ 10" | ≈ 4.5″–6.5″ | ≈ 3.75" |
| 18×7 | 18'0" × 7'0" | ≈ 10" | ≈ 4.5″–6.5″ | ≈ 3.75" |
| 18×8 | 18'0" × 8'0" | ≈ 10" | ≈ 4.5″–6.5″ | ≈ 3.75" |
Headroom and side room come from the door's track and hardware, not the door width, which is why they hold steady across the sizes above for a typical torsion-spring system. These are industry-typical minimums — manufacturers vary, so check your door's spec sheet before framing.
How to measure your rough opening
Measure in this order: width, height, headroom, then side room.
- Width. Measure the horizontal distance between the framing at the top, middle, and bottom of the opening. Use the narrowest of the three — framing settles unevenly over time.
- Height. Measure vertically from the floor to the underside of the header, at the centre and both sides of the opening. Use the shortest measurement if they differ.
- Headroom. Measure from the top of the finished opening to the nearest obstruction above it — a joist, duct, or the ceiling. Standard track needs roughly 10 inches; low-headroom track needs roughly 4.5 to 6.5 inches, depending on the spring system.
- Side room. Measure the clear wall space beside each jamb, from the edge of the opening to the nearest obstruction. Typical hardware needs roughly 3.75 inches per side for the vertical tracks and mounting brackets.
Framing basics: king studs, jack studs & the header
Three parts frame every garage door opening: king studs at the sides, jack studs carrying the header, and the header itself spanning the top.
- King studs: full-height studs on either side of the opening, running from the bottom plate to the top plate, that define the outer edge of the framed wall opening.
- Jack studs (trimmers):shorter studs nailed to the inside face of the king studs, directly under each end of the header, that carry the header's load down to the floor.
- Header: the structural beam spanning across the top of the opening, resting on the jack studs, that carries the wall and roof load above the door.
On a standard single garage door, the header is usually solid or built-up dimensional lumber sized from a span table. Once the opening needs to span wider, or sits under a load-bearing wall, span tables stop applying and the header becomes an engineered beam sized by a structural engineer — see how LVL, glulam, and steel headers are chosen on the engineered beam guide.
Wider openings need an engineered header
Past roughly 10 feet of span, or under any load-bearing wall, a garage door header stops being a lumber span-table lookup and becomes an engineered beam design. This is exactly what happens when two single garage doors become one wide double: the new opening usually clears 16 feet, well past what a standard lumber header can carry, so a licensed structural engineer sizes an LVL, glulam, or steel beam for the actual span and loads.
See the full comparison of beam types and when each is specified on the engineered beam guide, or how the whole two-to-one conversion works, post removal to permit to new door, on the conversion hub.
Rough opening questions, answered plainly
What is a rough opening?
A rough opening is the framed hole in the wall, built to the door manufacturer's specified width and height, before the door, jambs, or trim go in. For a garage door, the rough opening should match the door's nominal size exactly, with headroom and side room added as separate clearances above and beside it. .
What is the rough opening for a 16x7 garage door?
A 16x7 garage door needs a finished rough opening of 16'0" wide by 7'0" tall, plus roughly 10 inches of headroom above and about 3.75 inches of side room at each jamb, following typical manufacturer minimums. .
What is the rough opening for a 9x7 garage door?
A 9x7 garage door needs a finished rough opening of 9'0" wide by 7'0" tall, with the same typical headroom (about 10 inches standard) and side room (about 3.75 inches per side) as any other size. .
How much headroom does a garage door need?
Most garage doors need about 10 inches of headroom above the finished opening for a standard extension or torsion spring track. Low-headroom track hardware brings that down to roughly 4.5 to 6.5 inches when ceiling space is tight. Manufacturers vary, so the door's spec sheet is the final word. .
Is the rough opening bigger than the door?
Not in width and height: the rough opening is framed to match the door's nominal size exactly. The extra clearance sits outside that framed opening, as headroom above and side room at each jamb, which the track and hardware need but the door panel itself does not. .
Who sizes the header for a wide garage door opening?
A licensed structural engineer sizes the header for any wide or load-bearing garage door opening, calculating the beam for the specific span and the loads above it. Standard single-door headers can follow typical framing tables, but openings past about 10 feet, or any opening under a load-bearing wall, need an engineered beam design, not a table lookup. .
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