Austin setback requirements: front, side, rear and street side

The front setback rule almost nobody uses

§2.3 is written as a benefit and reads like a restriction, which is probably why it gets missed. The minimum front yard setback under Subchapter F is the lesser of:

• the minimum prescribed elsewhere in the Code — 25 feet in SF-2 and SF-3; or
• the average front yard setback of the nearby houses, if an average can be determined.

"The lesser of" is the operative phrase. If the houses on your block sit closer to the street than 25 feet, you may sit closer too — and on older Central Austin blocks, many do.

The average is taken from four principal residential structures that are (a) built within fifty feet of the front lot line, and (b) closest to and on the same side of the block as your lot. The fifty-foot filter matters: a house set far back is excluded from the average entirely rather than dragging it upward.

Fewer than four qualifying structures? Use however many there are on your side. None at all? Use the four closest on the opposite side of the block.

What the setback is measured to

§2.3.B.1 is specific: a front yard setback is the distance from the front lot line to the closest front exterior wall or building façade of the principal residential structure.

The wall, not the eave. Not the porch steps, not the bay window. Which matters for the average calculation as much as for your own house — you are comparing wall positions, and a neighbor's deep porch does not pull the average toward the street.

Setbacks are not the same thing as setback planes

Two different controls with confusingly similar names, and both apply at once.

A setback is a line on the ground. Your building must stay behind it.

A setback plane is a sloping surface in the air, rising from the property line at 45 degrees above a 15-foot vertical. Your building must stay under it.

So a house can sit perfectly within its 5-foot side setback and still breach the side setback plane at the second floor. The setback governs where the wall goes; the plane governs how tall it can be once it gets there.

HOME cut these substantially

The base numbers assume one house on a standard lot. If that is not what you are building, the setbacks shrink considerably.

Duplex, two-unit, three-unit (§25-2-773(B)) — front drops from 25 feet to 15. The rear stays at the base district minimum unless the lot backs an alley, or backs another lot zoned multifamily or less restrictive, in which case it drops to five feet.

Small lots (§25-2-779) — front 10 feet on SF-3 or more restrictive, five for a flag lot. Side and rear five feet. On SF-4A or less restrictive the interior side drops to three and a half feet, with the combined width of both interior side yards required to be at least seven feet.

Two provisions go to zero. Where an attached dwelling unit abuts a property line, the setback for that line is zero — that is what makes rowhouses possible. And a side or rear setback may be zero where the lot line is shared with another lot subdivided to under 5,750 sq ft and approved on or after 16 August 2024, so newly created small lots can build to a shared line.

The 5-foot rear setback does not reach every neighbor you might expect

City staff interpretation CI2026-0002 (May 2026) clarifies two limits on the alley-or-multifamily-adjacency rear setback reduction above, and both cut the other way from what a quick read suggests:

• The reduction runs off what is permitted next door, not what is built. Because single-family, two-unit and duplex uses are all permitted in Multifamily zoning districts, a project backing onto an MF-zoned lot generally qualifies. But three-unit is not a permitted use in Multifamily districts — so a three-unit project sited next to one stays at the standard 10-foot rear setback; there is no adjacency that gets it to five feet on that basis.
• Special Purpose districts do not count, even though some feel "less restrictive" in practice. A lot backing onto Park and Recreation Services, or another Special Purpose use, does not qualify for the reduction, because Special Purpose districts sit outside the hierarchy of base districts under §25-2-33 — and the reduction is defined by that hierarchy, not by how developed or quiet the adjacent use is.

The adjacency itself has to run along the rear lot line specifically — an alley or qualifying use along a side line does not trigger this reduction.

What may project into a setback

On a small lot §25-2-779(F)(6) allows a defined set of projections into a required yard:

• Two feet — windowsill, belt course, cornice, flue, chimney, eave, awning, box window or cantilevered bay window.
• Three feet — a one-story uncovered porch, stoop or steps.

The three-foot porch allowance is worth designing to. On a lot with a ten-foot front setback it is the difference between a step and something you can actually sit on.