How Much Does a Building Permit Cost in St. Louis County?

Permit Cost by Project

Do You Need a Permit?

The building permit fee comes from Table 1100.060, a stepped table by total construction cost, plus a $47 permit processing fee. Plan review and inspection are included. An $8,000 job pays $141 + $47 = $188, a $12,000 roof replacement $161 + $47 = $208, a $10,000 siding job $196, and a $25,000 job $232.

Small jobs are different. Section 1100.060 sets minimum totals of $94, $124, $141 or $171 depending on plan review and the number of inspections, and those minimums control at $6,000 and below. In the County's own records, residential alterations under the minimum were billed the $171 that applies where plan review is required, so a $2,400 interior strip-out is $171.

Trade permits are priced separately. Replacing a furnace or air conditioner is $94 per unit, one inspection included (1100.160). A water heater replacement is a $47 total fee. Electrical permits are $94 plus unit pricing (an EV charger circuit is $94 + $8 for one outlet = $102). Plumbing is $47 per inspection plus $6 per fixture plus the $47 processing fee. Each extra or additional inspection is $47.

The County's exempt list is SLCRO 1115.101 Section 105.2, which Chapter 1116 applies to one- and two-family homes. No permit is needed for sheds up to 120 square feet, fences up to seven feet in the rear or side yard (not around a pool, and not electrified or barbed), retaining walls up to 3 feet, painting, papering, tiling, carpeting, cabinets and counter tops, and ordinary repairs.

Roof replacement, siding, decks, remodels, EV chargers and water heaters need permits. The County's 2023 Ordinance Guidebook is reported to exempt same-opening window and door replacement, patios and driveways on grade, and soffit covering, but those items are not in the adopted code and we could not capture the Guidebook, so those figures are pending confirmation from the County. Check with the County before you start.

The county doesn't publish specific penalty multipliers in the fee ordinance we reviewed. That doesn't mean they ignore violations. Code enforcement finds unpermitted work through complaints, property sales and visible jobs. When they do, you usually pay retroactive fees plus extra. Stop work orders are prevalent. You can't sell the house cleanly with open violations either. The lack of clear penalty language in Ordinance 29,445 surprised me. Most cities spell it out. Here the documents stay quiet. Still, nobody wins by gambling. Pull the permit. The fees aren't outrageous enough to justify the risk. Get it on record and sleep better.

Permit duration details aren't spelled out in the main fee documents. You can get extensions though. The extension fee runs $47. Same price for a permit application extension. The exact inactivity or abandonment period was not listed in the tables we found, so verify that window with the county before you rely on a timeline. Plan your schedule tight. File early. Don't let the permit sit idle. If you need more time, pay the $47 and request the extension before it expires. Plain enough. But you have to stay on top of it.

Your contractor should pull the permits. Not you. That's the standard advice here like everywhere else. Still, the county doesn't publish clear owner-builder rules in the fee ordinance. We couldn't find specific homeowner language. This creates gray area. Licensed contractors carry insurance and take responsibility for code compliance. If they ask you to pull it yourself, treat that as a red flag. Make sure the contract says they handle all permits. Follow up to confirm they actually filed. Too many projects stall because this step got ignored.

St. Louis County prices each trade under its own section of Chapter 1100: building (1100.060), mechanical (1100.140 and 1100.160), electrical (1100.190) and plumbing (1100.200). There is no state surcharge.

A kitchen or bathroom remodel may be priced as one integrated permit on Table 1100.060 or as a building permit plus plumbing and electrical permits built from fixture, outlet and inspection counts. The County's own records price a typical remodel as one integrated permit (Sec. 1100.200(1)): $232 for a $25,000 kitchen and $208 for a $15,000 bathroom.

The Director may revise the $47 processing fee each year, effective July 31 (1100.035). Our figures use the amounts enacted in Ordinance 29,445.

How much does a building permit cost in St. Louis County?

A building permit in St. Louis County costs $188 on an $8,000 project and $232 on a $25,000 project: the Table 1100.060 fee plus $47 processing, with plan review and inspection included. Jobs of $6,000 or less fall under a minimum total of $94 to $171 depending on plan review and inspections.

Do I need a permit to replace a water heater in St. Louis County?

Yes. A water heater replacement needs a plumbing permit. It costs $47 in St. Louis County. Don't skip it. The county requires permits for this work even though many homeowners assume it's exempt.

Do I need a permit to build a deck in St. Louis County?

Yes. The County's exempt list has no deck item. A $12,000 deck pays $161 + $47 = $208 under Table 1100.060, plan review and inspection included.

How much is a plumbing permit in St. Louis County?

A water heater replacement is a flat $47 total. Other plumbing permits are $47 per inspection plus $6 per fixture plus the $47 processing fee, with a $94 minimum ($141 when two inspections are required).

Why does St. Louis County require so many separate permits?

Chapter 1100 of the county code requires individual permits for building, electrical, mechanical and plumbing work. Ordinance No. 29,445 kept this structure in the 2025 update. One project can trigger four permits and four fees. The county doesn't offer a single combined permit.