Cost · permit · scope
Garage planning guide
Plan a detached garage: the 200 sq ft permit line, fire-rated walls near a lot line, central Austin's floor-area cap and where Los Angeles puts it.
Permit complexity
High
Compare quotes per
garage
| Percentile | U.S. | California | Texas |
|---|---|---|---|
| 25th percentile | $23.32 | $28.72 | $21.48 |
| Median | $29.12 | $36.50 | $23.51 |
| 75th percentile | $36.94 | $46.07 | $27.78 |
Garage buying path
Draw the lot lines before the garage.
Past 200 square feet the permit is settled. The open questions are where the garage stands and how its walls are built, and each lot line answers both.
01 · Size
Past 200 square feet, plan for plans
The model code's exemption ends at 200 square feet of floor area, a 10-by-20-foot footprint. A larger garage is a permitted building, drawn, reviewed and inspected like one.
02 · Place
Measure to the lot lines
Less than 5 feet from a lot line the model code wants a one-hour wall, and less than 3 feet no openings in it. Zoning setbacks then decide whether the spot is allowed at all.
03 · Count
Count it against the lot
Central Austin caps a lot's floor area at 40 percent of the lot or 2,300 square feet, with a garage exemption of up to 450; Los Angeles puts a detached garage on the rear half of the lot.
Decision matrix
Compare one specification at a time
One-car garage
One vehicle and some storage
Specify inside dimensions, slab thickness, door size and opener, and any wall within 5 feet of a lot line.
Two-car garage
Two vehicles side by side
Specify the clear span, the header or truss design, both doors, and the slab's reinforcement and drainage.
Garage with a workshop
A shop or storage beside or above the bays
Specify floor loads, stairs, insulation and shop circuits; living space in it changes the review.
Quote controls
Keep every bid comparable
- Same footprint, wall height and roof pitch
- Slab thickness, reinforcement and footing depth itemized
- Fire-rated walls or eaves near a lot line shown on the drawings
- Doors, opener and circuits, an EV charger included, priced separately
- Permit, plan review and inspections assigned
Next best action
Calculate, then lock the scope.
Run the slab through the concrete calculator, and ask for quotes that separate the slab, the framing, any rated wall and the wiring.
Start with two separate questions
Required under the model code once a detached garage passes 200 sq ft of floor area.
Zoning places it: in Los Angeles on the rear half of the lot, and in Austin's SF-3 district an accessory building of one story or 15 ft may sit 5 ft from the rear lot line.
What usually decides the scope
- Floor area and height
- Distance to lot lines and the house
- Slab and footings
- Doors, lights and EV charging
- Driveway access
Lot lines
The model code rates a garage wall less than 5 feet from a lot line for one hour of fire resistance and allows no openings less than 3 feet from it; a detached garage within 2 feet of the line may keep 4-inch eaves.
Floor area cap
In central Austin a garage counts toward the lot's floor-area cap unless it qualifies for an exemption: up to 450 square feet for a detached garage at the rear, 10 feet or more from the house, or 200 for one closer.