Single-family attached subdivision in Austin: the §25-4-233 lot standards
Lots come in twos, and the site comes first
The rule that shapes everything else: attached lots may be created only in multiples of two per site. You are not subdividing into a row of arbitrary lots — you are creating pairs, each pair sharing the wall that makes them attached.
The site itself must be at least 7,000 square feet, and each resulting lot at least 3,000. Two 3,000 sq ft lots is 6,000, so the site minimum is doing real work — it is not simply the sum of the lot minimums.
| Standard | Requirement |
|---|---|
| Minimum site area | 7,000 sq ft |
| Minimum lot area | 3,000 sq ft |
| Minimum lot width | 25 ft — 20 ft on a cul-de-sac or curved street |
| Units per lot | Not more than one |
| Maximum height | 35 ft |
| Front setback | 25 ft |
| Street side setback | 15 ft |
| Interior side setback | 5 ft, except between attached units |
| Rear setback | 10 ft |
| Maximum building coverage | 40% |
| Maximum impervious cover | 45% |
The complete dimensional standard in §25-4-233(E).
Where you are allowed to do it
Three starting points qualify: unplatted land, a vacant platted duplex lot, or a platted lot developed with a duplex on or before 1 March 1987 — and in that last case only if the duplex complies with current regulations.
That 1987 date is the interesting one. An older duplex lot can be split into two attached fee-simple lots, which converts a single rental asset into two saleable homes — but only where the existing duplex still meets today's rules.
The side setback disappears at the party wall
Interior side yard setback is five feet, except between attached units. That exception is the whole mechanism: the two lots in a pair meet at a shared wall with no setback between them, while the outer edges of the pair keep the ordinary five feet.
So a pair reads as one building on the ground, with the property line running through the party wall.
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.