18×20 Double-Car Carport
An 18×20 freestanding carport sized for two vehicles side by side — solid shingled roof, framing drawings, cut list, and materials BOM.
7-day free trial, then $99 once. Framing drawings, cut list, and BOM for this exact carport.
Covered Area
360 sq ft
Post Layout
18′ × 20′ (post centerlines)
Post Height
12′
Roof Pitch
3/12
Design Wind
115 mph, Exposure B
Low-Side Clearance
7′ 6″
Drive-In Opening
16′ 1″ wide × 8′ 11″ high at the open end
About This Design
An 18×20 carport parks two vehicles side by side under one solid shingled roof, with enough width between them to load groceries without squeezing past a fender. It is freestanding — posts and a poured pad, no walls — engineered under the same ADR 027 post-and-beam ruleset as our pergolas, sized for the wider span a two-car bay needs.
The roof deck is solid shingle, not open lattice, so it is built to actually keep both vehicles dry.
Key Features
- 18×20 solid shingled roof on 8×8 posts
- Open-sided freestanding structure — no walls to frame
- Knee-braced 8×8 posts on standoff post bases — the same lateral detail as our pergolas
- Full cut list and materials BOM through the same framing engine as every plan
Build Notes
Set the posts on standoff post bases anchored to piers or the slab, run the beams and rafters per the framing drawings, then bolt a knee brace at every post-to-beam joint before sheathing and shingling the roof deck. The braces are the lateral load path — do not omit them; the engineering notes below give the through-bolts each brace end needs at the design wind.
The BOM covers posts, beams, rafters, roof sheathing, shingles, and hardware. Concrete for the pad is priced separately or supplied by others.
Best For
Right-sized for covered parking without the cost of a garage. Want an open-lattice shade structure instead of a solid roof? See our pergola plans.
Engineering Notes
The framing engine checks this carport's posts, knee braces, footings and roof uplift at 115 mph, Exposure B — the ASCE 7 basic wind speed across most of the interior United States. It is not a stamped design: a higher wind zone, an open or coastal site, or a jurisdiction that asks for sealed drawings needs a local engineer to review it.
- Knee-brace force 1919 lb on the 8 width braces (transverse wind) at 115 mph Exp B — use 2 × 5/8" through-bolts at each brace end in one row along the brace, 2.5″ apart, 4.375″ from the brace end (2101 lb, single shear, wet-service wind).
Interactive 3D Preview
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Frequently Asked Questions
How much does a 18×20 carport cost to build?
The materials estimate on this page is computed live from the plan's BOM: posts, beams, rafters, roofing and fasteners. Concrete, footings by others, and any electrical are accessories outside the BOM.
Do I need a permit for a 18×20 carport?
Freestanding accessory structures are frequently exempt below a jurisdiction's square-footage threshold, but setback and height rules still apply. Confirm with your local building department before building.
What materials are included in the 18×20 carport plans?
The plans include framing drawings with a cut list and a materials BOM covering the posts, beams, rafters, roof sheathing, shingles, knee braces, post bases, fasteners and hardware, plus the interactive 3D preview. A freestanding carport does not come with the multi-sheet printable permit plan set — that set draws a building's walls and foundation, which a carport has none of. Bring the framing drawings to your building department if your jurisdiction requires a permit.
