Austin lot size minimums and the 25-foot hazardous pipeline area

Last verified August 7, 2026 against the Austin Land Development Code · Kimbrough Gray · KiliGray Homes

A lot may not be reduced below the minimum area, width or depth. Where part is acquired for public use the remainder can qualify if it still holds a 30 by 40 foot buildable rectangle and at least half the minimum area. Separately, a restricted pipeline area extends 25 feet from a hazardous pipeline.

Applies to: Section 25-2-512 applies to lots subject to the district minimums. Section 25-2-516 applies to new construction intended for human occupancy after 20 April 2003 near a hazardous pipeline.

A lot may not be shrunk below the minimum

§25-2-512(A) states the obvious rule and is worth knowing precisely: a lot may not be reduced in area, width, or depth below the minimum requirements. All three dimensions, not just area.

That prevents the common manoeuvre of slicing a strip off a conforming lot and leaving something that meets the area test but is too narrow or too shallow to work.

Unless the city takes part of it

Subsection (B) handles the case where you did not choose the reduction — a portion of the original lot is acquired for public use. The remainder can still comply if three things hold:

before the acquisition, the lot complied with the lot size requirements;
the remainder contains a rectangular space at least 30 ft by 40 ft, usable for a building and excluding required yards; and
the remainder is at least 50% of the minimum area requirement.

The 30 × 40 test is the useful one, because it is concrete and it is measured after setbacks. On an SF-3 lot losing frontage to a right-of-way dedication, that rectangle is the question that decides whether anything can still be built.

1,200 square feet of clear buildable rectangle. That is what 30 × 40 means, and it must survive the front, side and rear setbacks. It is a far more demanding test than the 50% area threshold sitting beside it, and it is usually the one that fails.

The restricted pipeline area is 25 feet

§25-2-516 deals with building near a hazardous pipeline — one designed to transmit a "hazardous liquid" as federal regulation defines it.

The restricted pipeline area is:

anything within 25 feet of a hazardous pipeline; plus
anything within a hazardous pipeline easement.

Both, not either — so an easement wider than 25 ft extends the restricted area with it.

What counts as new construction

The section reaches new construction after 20 April 2003 of a structure intended for human occupancy, and the list of uses is explicit:

single-family residential, small lot single-family and single-family attached;
duplex and two-family residential;
mobile home residential; and
in a neighborhood plan combining district — the cottage, urban home and secondary apartment special uses.

That last inclusion is worth noting. The NP special uses are named specifically, so a cottage or secondary apartment is not outside the section by virtue of being small.

What we are not telling you. This page gives the section's definitions — the 25 ft area, what triggers it, which uses are caught. What is actually prohibited or required inside a restricted pipeline area is not restated here. Half-quoting an operative safety restriction would be worse than sending you to it, so if a pipeline is anywhere near your site, read §25-2-516 in full.

When these two bite

The lot size remainder test comes up on corridor lots facing a dedication. Before agreeing to anything, draw the 30 × 40 rectangle inside the post-dedication setbacks. If it does not fit, the remainder is not a buildable lot and that changes the negotiation entirely.

Pipelines are a title and survey question rather than a code one. The 25 ft figure is easy; finding out whether a hazardous pipeline or its easement crosses the site is the work. On any parcel with an unexplained easement strip, resolve what it carries before design.

Common questions

Can a lot be made smaller than the Austin minimum?

Not by choice. A lot may not be reduced in area, width or depth below the minimum. There is an exception where part is acquired for public use.

What happens if the city takes part of my lot?

The remainder can still comply if the lot complied before, the remainder holds a rectangular space at least 30 by 40 feet usable for a building excluding required yards, and it retains at least 50% of the minimum area.

How far from a pipeline can I build in Austin?

The restricted pipeline area covers everything within 25 feet of a hazardous pipeline, plus everything inside a hazardous pipeline easement. What is restricted within it is set out in §25-2-516.

Does the pipeline rule apply to a small cottage or secondary apartment?

Yes. The definition of new construction expressly includes the cottage, urban home and secondary apartment special uses in a neighborhood plan combining district.

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.

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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.