Austin multifamily open space: the ten-unit line in §25-2-780
Ten units decides which rule you get
§25-2-780 splits multifamily in two at ten dwelling units, and the two halves are different in kind, not degree:
- 10 or more units — comply with Subchapter E §2.7, private common open space and pedestrian amenities. Shared space, for the building.
- Fewer than 10 units — provide private personal open space, with its own percentage and its own dimensional minimums. Space attached to dwellings.
The intuition most people bring is that the small building gets the lighter rule. That is not what this says. The small building gets a rule with hard numbers on this page; the large one gets sent to a different subchapter entirely.
| Fewer than 10 units | 10 or more units | |
|---|---|---|
| What is required | Private personal open space | Private common open space and pedestrian amenities |
| Where the rule lives | §25-2-780(B) — below | Subchapter E §2.7 — not on this page |
| Minimum total | 5% of gross site area | Set by Subchapter E §2.7 |
| Ground-level area | ≥ 100 sq ft, ≥ 10 ft across each way | — |
| Above ground level | ≥ 50 sq ft, ≥ 5 ft across each way | — |
The ten-unit line is a count of dwelling units, not buildings or lots.
Five percent, and it has to be a usable shape
Under ten units, the total is five percent of gross site area — but a percentage alone would let you satisfy it with a strip a foot wide, so each area also has to hold a shape:
- At ground level: at least 100 sq ft, and not less than 10 feet across in each direction.
- Above ground level: at least 50 sq ft, and not less than 5 feet across in each direction.
"In each direction" is doing the work. A balcony 12 feet long and 4 feet deep is 48 sq ft and fails twice over — under the 50 sq ft area, and under the 5-foot dimension on its short side. The upstairs allowance is half the ground-level one on both counts, which is a realistic concession to what a balcony can be.
Three districts out, and one deal about parks
Subsection (A)(1) releases a large building from the common open space requirement in four situations. Three are simply places — the University Neighborhood Overlay (where the applicant has elected into Division 9), the central business district, and downtown mixed use. Dense places where private open space is the wrong ask.
The fourth is a trade, and it is the interesting one. A development certified under a local, state or federal affordable housing program is released if it sits within a quarter mile of an existing and developed public park or multi-use trail. Public open space substitutes for private open space, but only for projects that are already delivering affordability.
On a transit corridor, the site area minimum goes to zero
Subsection (C) is a separate bargain for multifamily in a transit-oriented development district, or on a core transit corridor or future core transit corridor. Two kinds of unit get their minimum site area cut to zero:
- a dwelling unit of 500 square feet or less — and its parking must be leased separately from the unit;
- a three-bedroom unit.
That pairing is deliberate. The smallest units and the largest ones are the two the market under-supplies, and a per-unit site area minimum penalises both — the studio because it is small, the family unit because it is expensive to build. Setting the minimum to zero removes the land cost per unit from both ends at once.
| Tenure | Share | Income limit | Term |
|---|---|---|---|
| Owner-occupied | 10% of the qualifying units | ≤ 80% MFI | 99 years from first CO |
| Rental | 10% of the qualifying units | ≤ 50% MFI | 40 years from first CO |
§25-2-780(C)(3). "Qualifying units" are those of 500 sq ft or less, or three-bedroom units. At least one unit must be affordable regardless.
Ninety-nine years, and a floor of one
The two affordability terms are not variations on a theme. Rental affordability runs 40 years; ownership affordability runs 99. That is the longest commitment period anywhere on this hub, and it reflects what the two tenures do — a rental restriction has to be re-imposed on each tenant, while an ownership restriction rides with the title through every future sale.
The income bands run the other way: ownership at 80 percent of median family income, rental at 50. Deeper affordability is asked of the shorter commitment.
And §25-2-780(C)(4) closes the arithmetic gap: notwithstanding the ten percent, at least one unit must be reserved as affordable. On a project with nine qualifying units, ten percent rounds to nothing — this stops that being the answer.
Common questions
Send us an address and we will tell you what we find
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.
Send us an addressWe 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.