Room Addition Permit in St. Louis (2026)
Room Addition permit requirements, fees, and process for St. Louis, MO. Find out if you need a permit and how to apply.
Yes, a Room Addition permit is required in St. Louis, MO.
A Room Addition permit is required in St. Louis, MO. The St. Louis Building Division (Community Development Administration) handles permit applications for St. Louis. Below you will find the current thresholds, fees, and process for obtaining a room addition permit in St. Louis.
When Is a Permit Required?
When a Room Addition Permit Is Required in St. Louis: All structural additions
Permit Fees
Room Addition Permit Fees in St. Louis: Based on construction value — typically $800-$4,000. Estimated timeline: 4-8 weeks.
Estimated timeline: 4-8 weeks
How to Get a Room Addition Permit in St. Louis
Verify whether your project meets the permit threshold in St. Louis: All structural additions.
Prepare your permit application and plans. Contact the St. Louis Building Division (Community Development Administration) at https://stlouis-mo.gov/government/departments/building for required documentation.
Submit your application online at https://stlouis-mo.gov/government/departments/building/permits.cfm or in person at the St. Louis Building Division (Community Development Administration).
Pay the permit fee: Based on construction value — typically $800-$4,000.
Wait for plan check approval. Estimated timeline: 4-8 weeks.
Schedule required inspections through https://stlouis-mo.gov/government/departments/building/inspections.cfm. All inspections must pass before project is finalized.
Important: St. Louis Building Division permit required. St. Louis's brick construction is common — additions to older masonry structures require special engineering considerations. Historic district review may also be required.
St. Louis Building Division (Community Development Administration)
Frequently Asked Questions
Source: St. Louis Building Code — Room Addition Requirements. Last verified April 6, 2026. View source