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Do I need a permit for a home addition? Yes in all 18 cities we read; here is what it involves

Yes, in every one of the 18 building departments whose rules we read: none exempts an addition of any size, and most send it through plan review. The exemptions end at detached sheds of 120 to 200 square feet. Austin filed 3,209 addition permits in three years, and the usual one stayed open 238 days from issue to final.

By Contractor Records · data through October 17, 2026

The rule in 13 cities, with their permit counts

Rules from each city's own page, read 23 October 2026. Counts are addition permits in the city's file over three years to September 2026 (Cape Coral's file starts January 2025); "usual days" is the typical time from issue to final inspection.

City What the page says Addition permits Usual filed value Usual days to final
Austin, TX No exemption: the exempt list stops at finish work and repairs up to 128 sq ft 3,209 — 238
Arlington County, VA "Exterior alterations are considered additions"; mechanical plans for "any addition that exceeds 500 square feet" 750 $80,000 235
Bellevue, WA "A permit with plan review is required for adding new square footage", second stories and dormers included 177 $125,000 364
Cary, NC Permit for "Interior and/or exterior wall demolition or addition"; a plot plan or survey when the footprint changes 303 $125,000 196
Columbus, OH "Room addition": permit and plan review 329 $113,269 258
Denver, CO Trade permits for an addition need "an issued Residential Construction Permit" first 864 $110,000 —
Minneapolis, MN "Most construction projects require you to obtain permits before you start the work" 404 $100,000 338
Naperville, IL "Additions to a building" need a permit 299 $94,500 422
San Diego, CA A permit "before constructing, expanding, altering" a home 671 $85,351 343
San Diego County (unincorporated) A permit to "construct, enlarge, alter" a building 158 $78,705 434
Saint Paul, MN "A general building permit is required to construct, enlarge, alter" a residence 189 $120,000 —
Anaheim, CA "Additions and remodels" need a permit 141 $50,000 303
Cape Coral, FL Addition is on its map of common permits 172 $125,000 301

Five more, without addition counts in our file: Sacramento County lists "Additions / Alterations", Citrus Heights answers YES for "ADDITION OF SQUARE FOOTAGE", Pikes Peak Regional lists "Room addition" and "Sun room", Elk Grove requires a permit to "construct, enlarge, alter" a building, and Seattle warns it "may issue a stop work order" on an addition started without one.

What an addition permit involves

Expect more than one review. Bellevue and Columbus require plan review for every addition. Cary asks for a plot plan or survey "any time that the 'footprint' of a primary or accessory building changes", which is how zoning setbacks get checked. Denver ties the electrical, plumbing and mechanical permits to the main construction permit, so the trades cannot start until it is issued. Arlington County adds mechanical plans above 500 square feet. Each trade then gets its own inspections.

What happens if you skip it

  • Seattle: a stop work order and fines of "up to $500 per day".
  • Colorado Springs area: Pikes Peak Regional files a "Certificate of Alleged Non-compliance" against the property with the county Clerk and Recorder, and the record owner pays to permit and inspect the work at sale time.
  • Naperville: its guide warns that non-compliant additions can affect title transfers when a home is sold.

More in permit vs no permit.

Who pulls it

The general contractor, almost always. Owners can pull their own in some places: Cary allows it if the house stays the owner's primary residence for 12 months after the work, and Pikes Peak Regional only for a primary residence you live in and only for work you do yourself. Saint Paul issues permits to "the homesteader of the property" or "a contractor licensed by the City of Saint Paul". If you are weighing an addition against a backyard unit, see ADU vs addition.

How long it takes

The usual addition permit closed in 196 days in Cary and 235 in Arlington County, against 338 in Minneapolis, 343 in San Diego and 422 in Naperville. Not all finish: 88.5% of Arlington County's addition permits a year or more old reached a final, against 65.3% of Naperville's and 20.6% of Saint Paul's. Hold real money back until the final passes.

Check it in five minutes

  1. Look up your zoning setbacks and lot coverage on the city's map; they decide how big the addition can be.
  2. Ask the contractor who draws the plans and how long plan review runs now.
  3. Check the contractor's past addition permits for finals. How to check a contractor's permit history shows how.

See every Austin addition builder by permits filed and finished →

What this does not tell you

We read 18 departments' rules. Our days run from issue to final and leave out plan review before issue. An addition filed as an alteration or as new construction is not in these counts. Prices are in home addition cost.

How we know this

Rules are quoted from the pages under Sources, read 23 October 2026. Permit counts, filed values, usual days to final and finished shares come from each city's permit file over the three years ending September 2026 (Cape Coral from January 2025). "Usual days" is the median from issue to final inspection; "reached a final" counts permits a year or more old.

Numbers come from City of Austin issued construction permits; Arlington County, VA building and trade permits; City of Bellevue permits on single-family homes and condo units; Town of Cary building permit applications (issued permits only); City of Columbus Building & Zoning Services permits on 1-, 2- and 3-family homes (the city's Accela permit layer); City of Minneapolis construction permits (CCS); City of Naperville building permits (the current permit system plus the city's older records); City of San Diego Development Services approvals, data through October 17, 2026. Nobody paid to be on this page and nobody can.

Questions

  • Is there any size of addition that does not need a permit?

    No, in the 18 departments we read. The exemptions stop at detached sheds of 120 to 200 square feet and finish work; anything attached that adds floor area is an addition. Bellevue also counts 'adding a second story, changing the slope of a roof and adding dormers'.

  • Does a sunroom or enclosed porch count as an addition?

    Usually, yes. Cary lists 'Converting a porch to a sunroom (adding glass or vinyl windows)' and 'sunroom' as permit work, Pikes Peak Regional lists 'Sun room' and 'Patio or deck enclosure', and Arlington County treats exterior alterations as additions for permit and fee purposes.

  • How long does an addition permit take?

    The usual addition permit reached its final inspection in 196 days in Cary, 238 in Austin and 235 in Arlington County, against 422 in Naperville. That clock starts at issue, after plan review.

  • What does a permitted addition cost?

    The usual filed value on an addition permit was $125,000 in Cary, $125,000 in Bellevue, $113,269 in Columbus and $80,000 in Arlington County. Filed values are what the contractor wrote on the application.

  • Do I need plans drawn by an architect?

    Plans, yes; who draws them depends on the city. Bellevue and Columbus require plan review for every addition, Cary wants a plot plan or survey whenever a building's footprint changes, and Arlington County wants mechanical plans for any addition over 500 square feet.

Build your own list

Every firm with that kind of permit on record. Pick what you value. The list moves.

Austin home additionArlington, VA additionBellevue additionCary additionColumbus, OH additionMinneapolis additionNaperville additionSan Diego addition

Related guides

For one city

All guides →

Sources
  1. Work Exempt from Building Permits — City of Austin Development Services (accessed 2026-10-23)
  2. Residential permits — Arlington County, VA (accessed 2026-10-23)
  3. Work requiring permits — City of Bellevue, WA (accessed 2026-10-23)
  4. Residential Permits FAQ — Town of Cary, NC (accessed 2026-10-23)
  5. Typical Residential Projects (BA 3/26) — City of Columbus, OH (accessed 2026-10-23)
  6. Quick Permits — City and County of Denver CPD (accessed 2026-10-23)
  7. Construction work exempt from permit — City of Minneapolis (accessed 2026-10-23)
  8. Guide to Building Permits (rev. 10/31/2022) — City of Naperville, IL (accessed 2026-10-23)
  9. When is a Permit Required? — City of San Diego Development Services (accessed 2026-10-23)
  10. PDS 110 Building Permit Requirements per Adoptive Ordinance (rev. 01/01/2026) — County of San Diego (accessed 2026-10-23)
  11. When is a permit required? — City of Saint Paul DSI (accessed 2026-10-23)
  12. When is a Building Permit Required? — City of Anaheim, CA (accessed 2026-10-23)
  13. Map of Common Permits — City of Cape Coral, FL (accessed 2026-10-23)
  14. Frequently Asked Questions — Sacramento County Building Permits and Inspection (accessed 2026-10-23)
  15. Projects Requiring a Building Permit (CHB0600, rev. 08/23) — City of Citrus Heights, CA (accessed 2026-10-23)
  16. Homeowner Permits — Pikes Peak Regional Building Department (accessed 2026-10-23)
  17. Construction Without a Permit — Seattle SDCI (accessed 2026-10-23)
  18. Do I need a building permit? — City of Elk Grove, CA (accessed 2026-10-23)