Austin conservation subdivision: smaller SF-1 lots, same number of homes
Smaller lots, the same number of houses
The instinct on reading "3,600 square foot lots in SF-1" is that this is a way to get more homes onto a large-lot property. It is not. §25-2-770(C)(1) caps the residential lots at the number that would otherwise be allowed under SF-1 zoning.
What changes is the arrangement. The same houses are gathered onto small lots, and everything left over becomes a single conservation lot held permanently as undisturbed open space. You are trading garden for commons, not buying density.
Two conditions gate it, and both must hold: the property must be zoned SF-1, and it must sit within the drinking water protection zone. Elect it and §25-2-770(B) supersedes the base district regulations entirely.
| Standard | Requirement |
|---|---|
| Minimum district size | 20,000 sq ft |
| Residential lot size | 3,600 – 5,750 sq ft |
| Minimum lot width | 50 ft |
| Lots permitted | Two or more, not exceeding what SF-1 would allow |
| Impervious cover, per lot | Maximum 60% |
| Impervious cover, whole property | The watershed maximum under Chapter 25-8 |
| Everything else | As specified for SF-1 |
§25-2-770(C) and (D). The conservation lot is the remainder of the property after the residential lots are taken.
The conservation lot has to be locked down
§25-2-770(E) does not merely say the remainder must be left alone. It requires three things together:
- Joint ownership and maintenance by the owners of the individual residential lots — not the developer, not the City, not an outside trust.
- Preservation as undisturbed open space through a binding legal agreement, such as a conservation easement, approved by the City.
- A plat note, also approved by the City, added at the time of subdivision.
The plat note is the part that outlives everyone. An easement can be misplaced in a title search; a plat note sits on the recorded subdivision plat and turns up whenever anyone looks at any lot in it.
Twenty thousand square feet is the entry ticket
§25-2-770(D)(1) sets a minimum district size of 20,000 square feet — just under half an acre. Below that the use is unavailable however the lots would be drawn.
That threshold also decides how often the SB 15 question above actually arises. Twenty thousand square feet is well under the five acres SB 15 needs, so a large share of conservation subdivisions will sit outside the state provision entirely and the city minimums will apply without argument.
Shared driveways are contemplated, not guaranteed
On lots of 3,600 to 5,750 square feet with a 50-foot minimum width, individual driveways consume a punishing share of the frontage. §25-2-770(D)(5) anticipates this: joint access driveways may be permitted as specified in Chapter 25-5, Article 5.
Note the verb. May be permitted, under another article's rules — this section opens the door and does not walk through it. Whether a shared driveway works on a given plan is decided by Chapter 25-5, not here.
Before that matters to you, check whether the statute reaches your land at all. It applies only to a tract that is five acres or more, has no recorded plat, sits in an area zoned for single-family homes, and is about to be platted. An existing platted lot is outside it entirely, which is most readers of this page.
If that does describe your land, raise it with the City before you draw lots. We are not telling you the city figures no longer apply, and we are not telling you they do — that is a question for the City and for your own advisers, and we would rather say so than guess.
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.