SF-4B zoning in Austin: the condominium site district

Last verified August 6, 2026 against the Austin Land Development Code · Kimbrough Gray · KiliGray Homes

SF-4B applies to a site of one to five acres. It requires at least 3,600 sq ft of site area per dwelling unit and 2,800 sq ft per building, caps buildings at two stories with a 10-foot plate height, and requires 10 feet between structures.

Applies to: Property zoned single-family residence condominium site (SF-4B). The section regulates the site as a whole rather than individual platted lots.

SF-4B is not in the zoning table. Its column in §25-2-492 carries footnote 5 instead of values, pointing here. That is because SF-4B does not regulate lots at all — it regulates a site, and asks how much site area each unit and each building consumes.

The unit of regulation is a site of one to five acres

§25-2-558(B) fixes the scale: an SF-4B site must be not less than one acre and not more than five acres. Both ends bind. It is not available for a single infill lot, and it is not available for a large tract.

Within that site, two separate area tests apply and both must be satisfied:

at least 3,600 sq ft of site area per dwelling unit; and
at least 2,800 sq ft of site area per building.

They are cumulative rather than alternative. On a one-acre site (43,560 sq ft) the unit test allows up to 12 dwelling units, and the building test allows up to 15 buildings — so on that site the unit count is what binds, and you could distribute those 12 units across as many as 12 separate buildings without the building test becoming the constraint.

Put several units in one building and the building test relaxes further, but the unit test does not move. Twelve units is twelve units.

Site width is measured per building, against the street

§25-2-558(C) and (D) set a width requirement that scales with how many streets a portion of the site faces:

facing a public right-of-way on one side — at least 40 feet of site width per building;
facing a public right-of-way on two sides — at least 50 feet per building.

This is what stops a long site being filled with narrow buildings crowded along the street frontage. A corner condition costs you ten extra feet per building.

Height is in stories, not feet — the only residential district that does this. §25-2-558(G) caps a building at two stories, and adds a limit no other district carries: a story may not exceed a plate height of 10 feet. If you arrive from the district comparison table expecting a figure in feet, this is why there isn't one.

Attic living space above the second floor

§25-2-558(H) permits habitable attic space above a second floor — effectively a third level — on two conditions:

the attic walls along the building perimeter may not exceed three feet in height; and
the floor area of the attic may not exceed 50 percent of the floor area of the second floor.

The three-foot perimeter wall is the controlling one architecturally. It forces the space into the roof form rather than allowing a full third story with a low ceiling — the volume has to be genuinely under a pitched roof.

Note this is a different mechanism from the Subchapter F attic exemption, which is about floor area rather than height. Different chapter, different test, different purpose.

Setbacks, and the ten feet between structures

§25-2-558(I) applies the familiar street setbacks, but only if a building faces a public right-of-way:

25 feet minimum front yard; and
15 feet minimum side street yard.

Buildings that do not face a street are not caught by that subsection at all — which is the point of a condominium site layout.

What governs internally is §25-2-558(J): the minimum distance between structures is 10 feet. That single figure does most of the work in shaping the site plan. Add a 15-foot rear yard setback, and a 10-foot setback between a rear access easement and any building or fence.

What the section does not say. §25-2-558 sets no minimum lot size, no building coverage percentage and no impervious cover figure. Those are simply absent — this page does not import SF-3's numbers to fill the gap, because nothing in the section authorizes that. Watershed limits and any overlay still apply on their own terms.

What SF-4B is actually for

It describes a specific product: a small, coherent development of detached or semi-detached houses on a shared site, held as condominium rather than platted into lots. The one-to-five-acre band, the ten feet between structures and the two-story cap all point at the same thing.

The two-story plate height limit is what most affects design. Ten feet of plate on each of two levels, with an attic confined behind a three-foot perimeter wall, produces a recognisably domestic scale — which is presumably the intent of a district meant to sit inside single-family neighborhoods.

Because the district is rare, we would confirm the site's zoning designation and read the section fresh before relying on any of it. It is not a district anyone carries in their head.

Common questions

What is SF-4B zoning in Austin?

Single-family residence condominium site district. It regulates a site of one to five acres rather than individual lots, requiring 3,600 sq ft of site area per dwelling unit and 2,800 sq ft per building.

How many units can I build on SF-4B land in Austin?

One per 3,600 sq ft of site area — about 12 on a one-acre site — subject also to at least 2,800 sq ft of site area per building.

How tall can an SF-4B building be in Austin?

Two stories, and a story may not exceed a plate height of 10 feet. It is the only residential district measured in stories rather than feet.

Can SF-4B buildings have attic rooms in Austin?

Yes, above a second floor, if the attic walls along the building perimeter do not exceed three feet and the attic floor area does not exceed 50% of the second floor area.

What setbacks apply in SF-4B in Austin?

25 ft front and 15 ft side street where a building faces a public right-of-way, a 15 ft rear yard, 10 ft between structures, and 10 ft between a rear access easement and any building or fence.

What impervious cover applies in SF-4B in Austin?

§25-2-558 sets none. The section regulates site area per unit and per building instead. Watershed limits and any overlay still apply.

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We do this research ourselves on every project we take on — zoning, floodplain, watershed, trees, whether it is a legal lot. Send us an address and we will run it and tell you what we find. It works the same whether you own a vacant lot, a house you are thinking of adding a unit to, or a house you are thinking of replacing. No charge and no strings, and if it is a bad lot we will say so.

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We are homebuilders, not the City of Austin. This page explains how we read the code in practice — it is not legal advice and it is not an official determination. Always confirm with Austin Development Services before you rely on it for a project. The authoritative text is the Austin Land Development Code; permitting questions go to Austin Development Services Department.