Do you need a site plan in Austin? Exemptions and review times

Last verified August 5, 2026 against the Austin Land Development Code · KiliGray Homes

Construction or alteration of four or fewer residential units on a legal lot needs no site plan, provided the improvement is not in the 100-year floodplain or the director finds an insignificant effect on the waterway. Most single-family and HOME projects are exempt.

Applies to: Development requiring approval under Chapter 25-5. The exemptions are determined by the director, so an exemption is a determination rather than something you assert.

Four or fewer units: no site plan

This is the exemption that covers almost everything this site discusses, and it is worth knowing before you budget for a review you may not need.

§25-5-2(B)(1) exempts construction or alteration of four or fewer residential units, provided:

the construction is on a legal lot or tract that contains four or fewer residential units — counting both proposed and existing; and
a proposed improvement is not located in the 100-year floodplain, or the director determines it will have an insignificant effect on the waterway.

A house is one unit. A three-unit HOME project is three. Both sit comfortably inside the exemption — so the entire Tier 1 envelope discussion on this site typically resolves at building permit, not site plan.

The floodplain condition is the one that bites. It is not about the lot; it is about whether a proposed improvement sits in the floodplain. A lot with a floodplain corner and a house well clear of it should still qualify, but that is the director's call.

An exemption is a determination, not a claim. §25-5-2(A) puts the decision with the director, who may require information to make it — or require revision of a previously approved site plan. So the practical answer to "do I need one" is "the director will tell you", and the value of knowing the rule is being able to demonstrate you fit it.

The other exemptions worth knowing

§25-5-2(B) is a list of thirteen. The ones that come up on residential work:

Interior alteration of an existing building that does not increase square footage, area or height.
Restoration of a damaged building, if it begins within 12 months of the date of the damage.
Demolition or relocation of a structure or foundation covering not more than 10,000 sq ft of site area under a City demolition permit — if trees larger than eight inches in diameter are not disturbed and the site is not cleared.
Removal of a tree not protected by the title.
A fence that does not obstruct the flow of water.
Clearing up to 15 feet wide for surveying and testing, unless a tree over eight inches in diameter is to be removed.

The demolition exemption has two conditions that are easy to trip over. Scraping the lot clear is not exempt, and neither is disturbing an eight-inch tree — so a demolition that would otherwise skip site plan review can be pulled back in by the landscaping.

Small projects: a lighter path, not an exemption

If a site plan is required, §25-5-3 lets the director determine the work is a small project, which carries a reduced process.

The core residential test — construction of a building or parking area — requires all three of:

no variance from a water quality regulation;
not more than 5,000 sq ft of impervious cover; and
a construction site not exceeding 10,000 sq ft — counting construction, clearing, grading, equipment access, driveway reconstruction, temporary installations, landscaping and anything else the director includes.

Note that the 10,000 sq ft is the construction site, not the lot. Staging, spoil and equipment access all count toward it.

The 2025 infill ordinance added a new category: construction of five to 16 dwelling units on a lot not exceeding 1.50 acres is a small project.

The 90-day guarantee for residential infill

Ordinance 20250306-037 added §25-5-112(E): if the standards are met, the director shall approve a site plan for a residential infill project in 90 days.

"Residential infill project" is defined narrowly. It means development of a site not exceeding 1.00 acre that consists of either:

five to sixteen dwelling units; or
a re-subdivision of property zoned SF-1, SF-2 or SF-3 that includes only land originally platted as a residential subdivision and does not require a plat vacation.

So it is aimed at the tier above what HOME made by-right — the five-to-sixteen band that needs a site plan but should not need a year of it.

The same ordinance also relieved those projects of some drainage requirements under a new §25-7-67: a resubdivision not exceeding 17,780 sq ft of gross site area, or a project with a drainage plan showing all runoff discharged to an existing storm drainage system or into right-of-way, need not comply with §§25-7-61, 25-7-151 or 25-7-152.

Where a disagreement goes

§25-5-112(C) splits appeals by subject matter, which is worth knowing before you file:

Board of Adjustment — if the requirement is from Chapter 25-2 (Zoning) or a separately adopted zoning ordinance. Setbacks, height, floor area, the setback planes.
Land Use Commission — if the requirement relates to Chapter 25-6 (Transportation), 25-7 (Drainage) or 25-8 (Environment). Access, drainage, impervious cover and watershed.

An appeal starts with a written objection to the director. And note that the Board of Adjustment is now the only route for relief from Subchapter F standards — the commission that used to grant them was eliminated in 2015.

What this means for a normal build

For a single house, or two or three units under HOME, the honest answer is usually that site plan review does not apply — the work is exempt under §25-5-2(B)(1) and the approval you are waiting on is a building permit.

Where it changes is the floodplain. A lot with any floodplain on it turns a routine exemption into a determination, and that is worth establishing early rather than discovering at submittal.

The other trap is demolition. Clients often assume tearing down the existing house is the simple part. It is exempt only if you do not clear the site and do not disturb an eight-inch tree — and on an older Central Austin lot there is nearly always an eight-inch tree in the way.

Common questions

Do I need a site plan to build a house in Austin?

Usually not. §25-5-2(B)(1) exempts construction or alteration of four or fewer residential units on a legal lot containing four or fewer units, provided a proposed improvement is not in the 100-year floodplain.

Does a three-unit HOME project need a site plan?

Not on the unit count — three units falls inside the four-or-fewer exemption. The floodplain condition still applies, and the director makes the determination.

What is a small project in Austin?

A category under §25-5-3 carrying a reduced process. For a building or parking area it requires no water quality variance, not more than 5,000 sq ft of impervious cover, and a construction site not exceeding 10,000 sq ft. Five to 16 units on up to 1.50 acres also qualifies.

How long does site plan review take in Austin?

For a residential infill project meeting the standards, the director shall approve in 90 days under §25-5-112(E). That definition is narrow — a site not exceeding one acre with five to sixteen units, or a qualifying re-subdivision of SF-1, SF-2 or SF-3.

Does demolition need a site plan?

Not if it covers 10,000 sq ft of site area or less under a City demolition permit, trees larger than eight inches in diameter are not disturbed, and the site is not cleared. Those last two conditions catch a lot of projects.

Where do I appeal a site plan decision?

To the Board of Adjustment for zoning requirements under Chapter 25-2, or to the Land Use Commission for transportation, drainage or environmental requirements under Chapters 25-6, 25-7 and 25-8. Start with a written objection to the director.

Working out what you can build?

We build in Central Austin and deal with this code on every project. If you own a lot and want a straight answer about what fits on it, we're happy to take a look.

Talk to us about your lot

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.