Do I need a permit for a full bathroom remodel in
Ballwin, Missouri?

Ballwin bathroom remodel permits — the key details

Ballwin's Building Department (part of the City of Ballwin Planning & Development Services) requires a permit anytime you relocate a plumbing fixture, add a new electrical circuit, install a new exhaust fan with ductwork, or modify the waterproofing assembly for a shower or tub conversion. IRC R302.1 (fire rating for bathrooms adjacent to living spaces) and IRC P2706 (proper trap sizing and slope for relocated drains) are the foundational rules. The key difference between Ballwin and neighboring cities is the pre-plan-review requirement: you cannot file and hope to get approval. The city's online portal requires you to upload fixture-location drawings, drain-line routing sketches, and electrical riser diagrams BEFORE submitting the formal permit application. If your drawings are incomplete, the department rejects the submission without issuing a permit number, and you must resubmit. This pre-review phase is free but adds 3–5 days. Once approved conceptually, formal permit filing takes another 7–14 days for staff review. Most residential bathroom remodels in Ballwin are assigned to the city's single residential plan reviewer, so any missing information delays the entire queue.

Plumbing work is the most heavily scrutinized component. IRC P2706 requires that a drain trap arm (the horizontal pipe between the trap and the vent) be no longer than three times the diameter of the drain — so a 1.5-inch toilet flange drain allows a 4.5-inch trap arm maximum. Ballwin inspectors measure this during rough-in and will flag violations; fixing an oversized trap arm mid-project is expensive and disruptive. Additionally, IRC P2706 requires that the trap arm slope at least 1/4 inch per foot downward toward the main stack. If you're relocating a toilet or vanity drain to a different wall, a drawing showing slope and distance is required in the permit packet. Tub-to-shower conversions require specific waterproofing documentation: Ballwin's code officer will not approve a conversion without a written specification of the waterproofing membrane. The city accepts PanelMax systems, Hydro Ban, Kerdi, or equivalent liquid-membrane systems bonded to cement board, but does not allow simple drywall + caulk. Your plan must list the product, thickness (minimum 1/2 inch cement board per IRC R702.4.2), and the membrane brand and coverage area. Failure to specify this on the front end means rejection and resubmission.

Electrical work triggers GFCI and AFCI requirements that many homeowners underestimate. IRC E3902 mandates GFCI protection for all receptacles within 6 feet of a sink, tub, or shower. If you're adding a new outlet or moving an existing one, that outlet and all downstream outlets on the same circuit must be GFCI-protected or fed through a GFCI breaker. Many homeowners and unlicensed contractors install a single GFCI outlet and assume protection is complete; Ballwin inspectors will reject this if downstream outlets lack proper protection or if the electrical plan doesn't show the GFCI source and affected outlets. If you're adding a new exhaust fan on a dedicated circuit, IRC M1505 requires that the exhaust ductwork terminate outside the building envelope with a back-draft damper, and the duct cannot be oversized (duct diameter should match the fan outlet diameter — using a 4-inch flex duct on a 3-inch fan outlet voids the ventilation). Your electrical plan must show the switch location, wire gauge, circuit breaker amperage, and the exhaust fan model number. Ballwin does not permit unlicensed homeowner electrical work for new circuits; you must hire a licensed electrician. If you're reusing an existing circuit to replace a light fixture in-place, owner work is allowed, but any new circuit or relocation requires a licensed electrician signature on the permit.

Waterproofing and ventilation are the two code categories Ballwin enforces most aggressively because they are the leading causes of bathroom failure and insurance claims. IRC R702.4.2 requires that all shower and tub surrounds be protected by a water-resistant membrane installed on framing before drywall or tile. If you're converting a tub to a shower, the new shower pan and surround must have a waterproofing system rated for wet areas; Ballwin's standard is cement board + liquid membrane covering the entire surround up to the showerhead, extended 12 inches above the tub rim or 36 inches if it's a walk-in shower. The city's inspectors will physically observe the membrane during rough-in and will photograph it; if it is not present or is incomplete, the rough-in inspection fails and work must stop until corrected. Exhaust ventilation must move 50–100 CFM (cubic feet per minute) depending on bathroom size; the permit packet must specify the fan model's CFM rating. Ductwork must be rigid or semi-rigid (not flex duct), slope downward to an exterior termination, and exit the roof or wall with a damper and weather-tight trim. Ballwin does not allow exhaust venting into attics or soffits; violations can trigger a code enforcement notice and a $200–$400 fine.

The inspection sequence for a full bathroom remodel typically runs: rough-plumbing (after framing, before drywall), rough-electrical (same stage), framing inspection (required by Ballwin even if studs are not being moved — this is a city quirk that differs from some counties), drywall inspection (often optional if you're patching only, but required for a gut remodel), and final inspection (fixtures installed, grout sealed, vanity and mirrors hung, electrical live). Timeline is 2–4 weeks from permit issue to final approval, assuming no rejections. If you have a pre-1978 home and you're disturbing painted surfaces, lead-paint rules apply (EPA RRP rule); you must hire a lead-certified contractor or do lead-safe work yourself. Ballwin does not issue its own lead permit but enforces federal RRP compliance. Permit fees are $250–$600 depending on valuation; Ballwin charges $3 per $1,000 of declared project cost. Inspection fees are included in the permit; there are no separate inspection charges. Once final approval is issued, you receive a signed permit card that must be kept with your home records for resale disclosure and future refinancing.

Three Ballwin bathroom remodel (full) scenarios

Shower waterproofing in Ballwin: what the city actually requires

Ballwin enforces IRC R702.4.2 strictly: every shower and tub surround must be protected by a water-resistant barrier installed on framing before drywall or tile. The most common rejection in Ballwin's residential bathroom permits is missing or incomplete waterproofing specification. Many homeowners and contractors assume that tile + grout + caulk is sufficient — it is not. Grout and caulk are not waterproof; they will eventually crack and allow water to penetrate to the framing, leading to mold, rot, and structural damage. Ballwin's code officer requires that your permit packet specify the exact waterproofing product: either a liquid membrane (Hydro Ban, Kerdi, Hydroban) applied over cement board, or a PanelMax-type pre-waterproofed panel system. The membrane must cover the entire surround up to the showerhead or 36 inches above the floor for walk-in showers, extended 12 inches above the tub rim for tub surrounds.

The inspection process is hands-on. During rough-in (before drywall or tile), the inspector will physically look at the waterproofing membrane and verify that it is the product approved in the permit. If you substituted a cheaper product or did not install it, the inspection fails. The inspector photographs the membrane; you must upload the photos to the permit file. Once drywall or tile is installed, the waterproofing is hidden, and the inspector cannot verify it anymore — so the rough-in inspection is your only verification point. If the membrane is not correct or complete at that stage, you must remove drywall or tile, correct the membrane, and call for a re-inspection. This rework can cost $500–$2,000 depending on how much tile has been installed.

Ballwin does not permit improvisation. Some contractors install Durock (cement board) without a separate membrane, relying on the board's water resistance — this fails Ballwin's code review. Others use RedGard or similar liquid membranes but apply them too thin or miss areas — also a rejection. The safest path is to use a proven system like Kerdi (which is waterproofed throughout the board itself), Hydro Ban (liquid applied per manufacturer specs), or PanelMax (factory waterproofed). Your permit plan must list the product name, thickness, coverage area, and the contractor's signature confirming installation per manufacturer spec. If you are a homeowner doing DIY work, you are responsible for correct installation; the city will not excuse improper waterproofing because you did it yourself.

Plumbing fixture relocation and trap-arm code in Ballwin

IRC P2706 (Drainage Fittings) sets the trap-arm rule that trips up many Ballwin bathroom remodels: a trap arm cannot be longer than three times the diameter of the drain. For a 1.5-inch toilet drain, that means 4.5 inches maximum from trap to vent. For a 1.25-inch vanity drain, 3.75 inches maximum. This rule exists because a long, slack trap arm allows water in the trap to evaporate or siphon out, breaking the water seal that prevents sewer gases from entering the home. Ballwin's inspectors measure trap-arm length during rough-in and will flag violations. If you are relocating a toilet 10 feet from its original location, the new drain line will likely have a longer trap arm than allowed. The solution is to relocate the vent stack or install an air admittance valve (AAV or Studor vent) closer to the relocated fixture — both solutions add cost and complexity.

Another common issue is trap-arm slope. IRC P2706 requires that the trap arm slope downward at least 1/4 inch per foot toward the main vent. If the arm slopes upward or is level, water pools in the arm and breaks the seal. Ballwin inspectors will verify slope during rough-in, and your permit drawing should show slope calculations. Many homeowners and contractors do not account for slope when planning a relocation, and then discover mid-construction that the new drain line will not fit in the wall cavity at the required slope. This leads to delays and costly rework.

For toilet drains specifically, the flange must sit on the finished floor. If the bathroom floor is being raised (new tile that is thicker than old), or if you're relocating the toilet to a different floor elevation, the flange height must be verified and the drain line slope recalculated. Ballwin does not issue variance or waiver letters for trap-arm length violations; if your design violates the code, you must redesign. The best practice is to hire a plumber to design the new drain routing before you file the permit. The plumber's sketch showing trap-arm length, slope, and vent routing can then be attached to the permit application, reducing the likelihood of rejection.

Common questions