18 feet wide · 8 feet high · double
18x8 garage door
Two vehicles, one tall, with room to walk between them.
Where it comes from
Why an opening is 18x8
Width and height together, which means somebody specified it. Eighteen by eight is the double for a household with two large vehicles, at least one of which is tall, and it is the size that shows up on newer builds in places where that is normal.
Two full-size trucks, side by side, with room to walk between them and clearance for whatever is on the roof. There is very little that lives on a domestic driveway that this will not take.
Fitting one
What changes at 18x8
The heaviest of the common residential doubles. Two springs, struts, a long shaft, and sections that are a genuine two-person lift. This is also the size where a real contractor's price list starts to climb — the same panel style that costs one price at sixteen feet costs more at eighteen by eight, which is one of the few places where size genuinely moves the number.
The opener. Three-quarter horsepower at the very least, and more if the door is insulated. At this weight the opener is doing real work every cycle and the cheap one fails first.
Getting hold of one. Stock in common configurations, ordered in the rest. Wind-rated versions in coastal counties are an order.
The mistake
What people get wrong about a 18x8
Assuming the headroom is fine because the ceiling is high. An eight-foot door needs its clearance measured from the top of the OPENING, not the floor, and an eight-foot opening in a ten-foot garage leaves less room above it than a seven-foot opening in a nine-foot one.
What it costs
A 18x8 door, installed
| Material | Typical, installed | Worth knowing |
|---|---|---|
| Sectional steel | $3,240 | The baseline, and most of the doors on most streets. |
| Insulated steel | $3,990 | Worth it on an attached garage or one with a room above it. |
| Steel overlay, carriage look | $6,790 | The swing-door look on a sectional door. Where the price starts climbing. |
| Wood overlay | $14,640 | Real wood over an insulated core. Beautiful, and it needs refinishing. |
| Aluminium and glass | $8,390 | Modern, lots of daylight, lower insulation value. |
The gap between the cheapest and dearest 18x8 is $16,620, and not one dollar of it is the size. Same opening, same fitting, same morning — what moves the number is the model: panel style, insulation and overlay. Why a door costs what it does →
National guide ranges, checked September 2026, not a quote — what moves the number.
That is the door, the tracks, the springs, fitting it and taking the old one away. An opener, a keypad and any work on the opening itself are separate — what is in a quote and what is not.
Before you book it
What the extras cost · why nobody should touch their own springs
Framing
Rough opening for a 18x8
18'0" × 8'0"
For a sectional door the rough opening equals the door size exactly. A 16x7 door needs a 16'0" wide by 7'0" high finished opening.
Fits
What goes through a 18x8
- Compact car (Civic) — 11.2' spare across the mirrors
- Sedan (Camry) — 11.0' spare across the mirrors
- Small SUV (RAV4) — 10.9' spare across the mirrors
- Large SUV (Suburban) — 10.5' spare across the mirrors
- Full-size pickup (F-150) — 10.0' spare across the mirrors
- Cargo van (Transit) — 9.9' spare across the mirrors
- Pickup, tow mirrors (F-250) — 9.2' spare across the mirrors
Two side by side: compact car (civic), sedan (camry), small suv (rav4), large suv (suburban).
Questions
18x8 garage doors, answered
How much does a 18x8 garage door cost?
A 18x8 in sectional steel runs about $2,130 to $4,350 installed, and $2,630 to $5,350 insulated. That is the door, the tracks, the springs, fitting it and taking the old one away. An opener is separate.
What is the rough opening for a 18x8 garage door?
18 feet by 8 feet, exactly. For a sectional door the rough opening is the door size — framing it wider leaves a gap the seal cannot close.
How much clearance do you need for a 18x8?
12" of headroom above the opening for a standard torsion setup, 9" front, 4.5" rear of sideroom each side for the vertical track, and the door height plus 16 inches of backroom. The full table, including low-headroom kits, is on the rough opening guide.
Is a 18 ft garage door big enough for two cars?
Two of these, comfortably: compact car (civic), sedan (camry), small suv (rav4), large suv (suburban). Anything wider across the mirrors gets tight — measure yours, mirror to mirror, before you decide.
Is an insulated 18x8 worth the extra?
About $500 to $1,000 more. Yes if the garage is attached or there is a room above it — you feel it in the summer and in the heating bill. A detached garage you only park in: skip it.
How long does it take to fit?
Four to six hours, plus an hour or two to take the old one away. Plan on losing the morning.
What opener does a 18x8 need?
Three-quarter horsepower at the very least, and more if the door is insulated. At this weight the opener is doing real work every cycle and the cheap one fails first.
Is a 18x8 a stock size?
Stock in common configurations, ordered in the rest. Wind-rated versions in coastal counties are an order.
The next size up
18x8 or 20x10?
A 20x10 is 2 feet wider and costs roughly $2,500 more in steel. Worth it if you open car doors inside the garage rather than on the driveway. See the 20x10 →
Other sizes