Concrete driveway extension in Austin: where the property line falls
Everything about a driveway extension in Austin turns on one question: does the new concrete stay on your lot, or does it change the approach where the drive meets the street? Widening beside the garage, adding a parking pad or a strip for trash bins stays on private property, which the City exempts from a building permit. A wider curb cut, a new approach or any sidewalk or gutter work is in the public right-of-way and needs a Driveway/Sidewalk permit.
Driveway extension options
| Job | Typical size | Right-of-way permit? |
|---|---|---|
| Widen beside the existing drive | 4 to 10 ft wide, drive length | Only if the approach or curb changes |
| Side parking pad | 10x20 per car | Only if it needs its own curb cut |
| Turnaround or apron | Varies | Usually no |
| Trash and recycling strip | 4x10 or so | No |
| Wider curb cut and approach | To match the wider drive | Yes, Driveway/Sidewalk permit |
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Permit column from the City of Austin's exemption list and Right-of-Way Permits page. HOA rules can limit driveway width separately.
Driveway extension cost in Austin
| Extension | Area | projectcosted Austin | HomeBlue Austin ($6 to $10) |
|---|---|---|---|
| 4x30 strip | 120 sq ft | $676 to $1,351 (computed) | $720 to $1,200 |
| 10x20 parking pad | 200 sq ft | $1,126 to $2,252 (published) | $1,200 to $2,000 |
| 10x40 widening | 400 sq ft | $2,252 to $4,503 (published) | $2,400 to $4,000 |
| 20x20 double pad | 400 sq ft | $2,252 to $4,503 (published) | $3,400 to $5,900 (published) |
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Unmarked HomeBlue rows computed at its Austin $6 to $10 per sq ft reinforced rate. Saw-cutting, tearing out turf or old paving ($1.10 to $1.70 per sq ft for slab demolition, HomeBlue Austin) and any right-of-way work are extra.
Building it to match the old driveway
Tie-in
The old edge is saw-cut straight, and the new slab is either doweled to it or isolated with a joint so the two can move a little independently. On clay that heaves, an isolation joint keeps a crack from traveling from one slab into the other.
Thickness and slope
Match the existing drive's thickness or go thicker, with rebar for vehicles. Keep the slope running the same way as the old drive, and within 10 feet of the house at least 2 percent away from it (IRC R401.3).
Impervious cover
The extension adds to the driveway line on the City's impervious cover worksheet. Check the lot's zoning limit, generally 45 percent on SF-3, before settling on a size; the impervious cover guide walks through the math.
- A photo of the drive from the street and from the garage
- The width you want and how far back it should run
- Whether the curb cut needs to get wider
- Trees near the edge of the drive
- Any HOA approval the change needs