Computed from 755 recent building-permit filings in Austin, TX — what people actually declared, not survey guesses.
✓ Verified from 755 recent building-permit filings in Austin, TX
Every filing behind this range declared a residential renovation cost between $1,000 and $2,000,000 — outliers and commercial-scale projects are excluded. We only publish a range once at least 30 qualifying filings exist for a city/project combination; this one has 755.
Data refreshed September 2026
The short answer: a typical home addition / extension in Austin costs around $75,000, with half of all projects landing between $25,000 and $170,000. If a quote falls well outside that range, it isn't automatically wrong — but it deserves an explanation you can understand.
Much of Austin sits on expansive clay soil, which drives foundation movement and is a common source of scope creep on additions, decks and pool projects once excavation starts.
Long, hot summers push HVAC and roofing demand — and pricing — higher in peak season; permit filings for those trades are consistently heavier from late spring through summer.
The middle half of the published sample spans $25,000 to $170,000. That is a 193% spread around the median, so the details of your scope matter more than the label on the project.
An addition or extension can include foundations, structure, roof tie-in, envelope, services, and interior finishes for the new space.
Land purchase, temporary accommodation, major utility upgrades, furnishings, and redesign after approval are commonly outside the filing value.
This guide is based on 755 qualifying permit filings, not completed projects. Permit values reflect what applicants declared and can differ from the final paid cost.
Every figure on this page is computed from declared valuations on building permits filed with Austin Development Services, published via the City of Austin Open Data Portal. We report the 25th percentile, median and 75th percentile of 755 recent residential filings — never a single-point "average". Declared values are what applicants file, not final invoices, so treat the range as planning guidance rather than a quote. Full methodology →
The source dataset is maintained by Austin Development Services. The published sample is the subset classified as residential, matched to this project type, and carrying a declared valuation from $1,000 to $2,000,000. The count above is the number of qualifying filings used for this city and project, not the number of homes or completed invoices.
Open the City of Austin Open Data Portal datasetBased on 755 recent building-permit filings with Austin Development Services, the median declared cost is $75,000. Half of all projects fall between $25,000 and $170,000.
No. Permit valuations are what applicants declare to Austin Development Services when filing, not final invoices — and Austin Development Services doesn't independently verify the declared value. Treat the range as planning guidance and a sanity-check against the quotes you receive, not a price to hold a contractor to.
Much of Austin sits on expansive clay soil, which drives foundation movement and is a common source of scope creep on additions, decks and pool projects once excavation starts. That local variation is on top of the usual differences in size and specification, which is why we publish the 25th percentile, median and 75th percentile instead of a single misleading "average" — you can see where a quote sits in the real distribution.
Planning something else, or somewhere else? Request a city or project — requests decide what we ingest next.