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Free starting design ยท three-car garage

30x40 garage plans

1,200 sq ft, 10 ft walls, 6/12 roof.

38 of 38 planner checks passed
The 30x40 three-car garage, drawn by the garage designerThe 30x40 three-car garage with its width and lengthThe framing of the 30x40 three-car garage: studs, plates, headers and trusses, without the siding or the roofThe 30x40 three-car garage seen from above with the roof off, showing the wall layout and the door openings
Drawn by the designer from this plan
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Preliminary checks for 30 psf ground snow, 115 mph wind, 36 in frost line. Local approval not checked.

Footprint
30x40 ft
Doors
16' x 7' overhead, 9' x 7' overhead, walk door
Trusses
21 at 2'
Slab
4 in, frost wall

About $21,500 in materials, before sales tax, delivery and tools.

Building it? The $79 builder's plan dimensions every piece. See sample sheets

Planner checks

38 of 38 automated checks passed ยท 4 external items remain. Local approval not checked. 1 item for your builder or engineer: seismic design category.

Each bar is how much of its bending or deflection limit a member uses at 30 psf of snow. We stop at 95%: past that, a header or a stud goes to the next size.

  • Header, 9' x 7' overhead door, right sidewall97% of 95% allowed3-2x12, 9' span
  • Header, 16' x 7' overhead door, right sidewall65% of 95% allowed3-ply 1-3/4 x 14 LVL, 16' span
  • Header, walk door, left sidewall60% of 95% allowed2-2x8, 3' 2" span
  • Header, window, left sidewall57% of 95% allowed2-2x8, 3' 1/2" span

what this design uses room to spare

Green passes the rule or the calculation we checked against, amber asks you to look at something before you build, red fails it. These are preliminary checks, not a structural approval; your local building authority reviews and approves.

Specification

The 30x40 three-car garage, part by part.

The building

Footprint
30x40 ft, 1,200 sq ft
Walls
10' 1-1/8" plate height
Roof
6/12 gable
Doors
16' x 7' overhead, 9' x 7' overhead, walk door

Slab and frame

Slab
4 in, 28 cu yd of concrete
Footing
36 in down, frost wall
Trusses
21, 30' span
Anchors
34 bolts

Cost and time

What it takes to build.

Materials, about (rounded estimate, before sales tax, delivery, labor and site work)$21,500

  • Foundation$4,753.30
  • Lumber$2,380.38
  • Trusses$4,725.00
  • Sheathing and siding$3,246.27
  • Roofing$3,112.90
  • Doors and windows$2,540.56
  • Hardware$698.57

Shelf prices from Lowe's, Home Depot and Summertown Metals, read Sep 30, 2026 to Oct 25, 2026. Trusses and concrete estimated from published ranges. Before sales tax, delivery, labor and site work.

At shelf prices
$12,274.48
Trusses and concrete, estimated
$9,182.50
Exact sum
$21,456.98
Per sq ft of floor
$17.88
Build time
155 to 230 h
a crew of two, about 10 to 15 working days; a broad reference, not a schedule
Labor if hired, broad reference
$24,000 to $60,000
Separate from the materials.

Prices differ by store and by week: size your own garage in the garage cost calculator, which runs the same numbers.

Free and paid, side by side

Design it free. Build it from the $79 plan.

Free

On this page and in the designer, no account

  • This design in 3D, and every change you make to it
  • Every planner check, with its rule and source
Cost estimate
About $21,500 in materials, line by line, on this page. See the estimate
Summary PDF
The design, its checks and its materials list on a few pages. A summary, not the build drawings.
Customize this design, free

$79 once

The drawings you build from, for the design you finish. 34 Letter sheets for the 24x24 garage.

  • The dimensioned layout
  • Every wall framed, with openings and heights
  • The roof frame
  • The cut list, the shopping list with store prices and the build, step by step
Get the $79 plan for this design

You check out in the designer, with this design loaded. If the plan has an error, we fix it or refund you within 30 days. Guarantee terms.

Real sheets from the 34-sheet sample plan for the 24x24 garage

The sample was printed on an earlier date, so its prices can differ from the estimate above. Your plan prints the same prices as the estimate.

  • Sample sheet 1 of 34: foundation and slab

    Foundation and slab

  • Sample sheet 2 of 34: complete before construction

    Complete before construction

  • Sample sheet 3 of 34: build steps

    Build steps

  • Sample sheet 4 of 34: shopping list

    Shopping list

Build phases

From the first cut to the last board in 5 phases.

About 155 to 230 hours for a crew of two, about 10 to 15 working days; a broad reference, not a schedule. Each picture is this design at the end of its phase, drawn by the designer, with that phase's new parts in color.

  1. The 30x40 three-car garage after phase 1: slab and footing

    01

    Slab and footing

    Dig to the frost depth, form and pour the footing and a 8 in frost wall, then the 4 in slab inside it. Set the anchor bolts in the wet concrete and let it cure before you frame.

  2. The 30x40 three-car garage after phase 2: wall framing

    02

    Wall framing

    Frame each wall flat on the slab with its studs, plates and headers, stand it, brace it plumb and tie the corners.

  3. The 30x40 three-car garage after phase 3: trusses

    03

    Trusses

    Set the trusses from the truss maker on the double top plate at their spacing, brace them as its drawings say and tie them down.

  4. The 30x40 three-car garage after phase 4: roof and walls closed

    04

    Roof and walls closed

    Sheathe the roof and the walls, then roof it. The building is dry once the roof covering is on.

  5. The 30x40 three-car garage after phase 5: doors and finish

    05

    Doors and finish

    Hang the overhead doors, the walk door and the windows, then flash, trim and side the walls.

This is the summary. The $79 builder's plan breaks these phases into a build order with the new parts highlighted, a how-to detail and a check at each step.

Questions

Anything else? Write to us or read the questions about all plans.

Questions about the 30x40 plan

For this 30x40 design the materials come to about $21,500 at the store prices we read, $12,274.48 at shelf prices plus $9,182.50 estimated from published ranges, before sales tax, delivery, labor and site work. If you hire the build out, published price guides give a broad range of $24,000 to $60,000 on top, a reference and not a quote. Every line, with its store and date, is in the materials list on this page.

As drawn, this 30x40 garage is 1,200 sq ft, past the size where the code exempts a detached garage from the frost-depth footing, so the plan draws a footing 36 in down with a 8 in frost wall and a 4 in slab. Your building department sets the frost depth.

The plan draws a 3-ply LVL header over each 16' door, from the code span table for your snow load, with 2 king studs a side. Your building department confirms the table it uses.

Sizes to compare

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Inside a framed garage: wall studs sheathed in OSB, roof trusses overhead, a large header over the door opening and two sawhorses with a stack of lumber on the slabIllustration