Austin, TX · Guide
Impervious Cover in Austin: What a New Patio or Driveway Means
Austin limits how much of a lot can be covered by hard surfaces, and new concrete counts, so it's worth checking your numbers before planning a slab.
01 — What this covers
The work itself
- What counts as impervious cover
- Typical limits in single-family zoning
- Stricter limits over the Barton Springs Zone
- How to estimate your lot's current coverage
- Ways to fit a project under the limit
- Drainage charges and impervious area
- Permits and where to confirm the rules
- Rules outside Austin city limits
02 — Detail
What impervious cover means
Impervious cover is any surface that keeps rain from soaking into the ground: the roof of the house and garage, driveways, patios, walkways, pool decks and other paved areas. Austin limits how much of each lot can be covered this way to reduce runoff, flooding and pollution in creeks.
For a homeowner, the practical point is simple: concrete you add counts. A patio, a wider driveway or a new walkway increases your total, even if the house itself doesn't change.
The rules are part of the city's development code, and the exact numbers depend on your zoning and where your lot sits in the watershed. That's why the first step is finding out which rules apply to your address.
03 — Detail
Typical limits
In Austin's most common single-family zoning districts, the impervious cover limit is 45 percent of the lot. On a 7,000 square foot lot, that's about 3,150 square feet of house, garage, driveway, patio and other paving combined.
Over the Barton Springs portion of the Edwards Aquifer, limits are far stricter under the Save Our Springs ordinance: as low as 15 percent of net site area in the recharge zone and 20 percent in the contributing zone.
Other overlays and older subdivisions can have their own figures, so treat these as orientation, not as a calculation for your lot.
04 — Detail
Estimating where you stand
To get a rough idea, add up the footprint of the house and garage, the driveway, the patio and the walkways, and divide by the lot area. If you're already near the limit, a large new slab may not fit as planned.
Your contractor can measure existing paved areas during the estimate visit. For an official answer, the city's development services can confirm the zoning and limits that apply to your property.
It's much easier to adjust a design on paper than to change a project after forms are set.
05 — Detail
Ways to make a project fit
If you're close to the limit, a smaller slab or a different shape may work. Removing an old paved area you don't use, such as a side walkway or an unused parking pad, can free up room for the patio you want.
Ribbon driveways, with a planted strip down the middle, reduce paved area compared with a full-width slab. For part of a patio, other surfaces may be treated differently; check how the city counts them before relying on that.
Uncovered wooden decks and some unpaved areas are treated differently from concrete in certain city calculations, but the treatment for zoning purposes should be confirmed for your case.
06 — Detail
Drainage charges and permits
Austin's utility bill includes a drainage charge that is based on the impervious area of each property. Adding concrete can increase it slightly over time.
Projects that add impervious cover, and work in the right-of-way such as driveway approaches, can require permits. Ask your contractor who handles them and whether they're included in the estimate.
Outside Austin city limits, in Round Rock, Leander and Georgetown, the codes are different and often simpler for small residential slabs, but HOA rules commonly apply instead.
How we work
Step by step
- 01
Find your zoning and lot size.
- 02
Add up existing house, garage and paved areas.
- 03
Compare with the limit for your zoning and watershed.
- 04
Adjust the project if needed before getting estimates.
- 05
Confirm with the city and arrange permits where required.
What it costs
Checking impervious cover costs nothing but time, and it can save the cost of redesigning or removing concrete later. Ask for it to be part of the estimate visit.
Questions
Impervious Cover in Austin: Patios and Driveways — asked and answered
Does a patio count as impervious cover?
Yes. Concrete patios, driveways and walkways all count.
What is the limit for my house?
In many single-family zones it's 45 percent, but it depends on your zoning and watershed. The city can confirm it for your address.
Can I remove old paving to make room for a patio?
Often, yes. Removing unused paved areas reduces your total.
Do these rules apply in Round Rock or Georgetown?
No. Those cities have their own codes, and HOA rules often matter more there.
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