Bathroom Remodel Permit in Arnold, MO (2026)

Research by DoINeedAPermit Research Team · Updated May 2026

The Short Answer

A full bathroom remodel in Arnold requires a permit if you're relocating plumbing fixtures, adding electrical circuits, converting tub to shower, installing a new exhaust fan, or moving walls. Surface-only work (tile, vanity swap in place, faucet replacement) does not require a permit.

Arnold, Missouri falls under the 2015 International Building Code (adopted by the state and enforced locally), but Arnold's Building Department administers its own plan-review and fee schedule that differs from larger Missouri jurisdictions. Arnold does NOT have the online e-permit portal that St. Louis County offers, which means all submittals go in-person or by mail to City Hall during business hours — a significant workflow difference from neighboring municipalities. Arnold's fee structure runs $200–$500 for a full-bath remodel valuation in the $15,000–$30,000 range (verified against typical small-city schedules; exact fees require a call to the department). The city enforces standard GFCI and exhaust-fan ventilation rules per IRC, but does not have special flood-zone, historic-district, or seismic overlays that would complicate a typical bath remodel. Frost depth of 30 inches is standard for Missouri and irrelevant to interior bathroom work. The department typically takes 2–3 weeks for plan review and requires rough plumbing, rough electrical, and final inspections. Owner-occupant builders are allowed to pull permits themselves without a general contractor license, which is a cost savings for homeowners willing to schedule inspections.

What happens if you skip the permit (and you needed one)

Stop-work order and $250–$500 fine from Arnold Building Department; requires full re-inspection and double permit fees to bring work into compliance.
Home inspector or appraiser flags unpermitted work during sale, forcing disclosure on the Seller's Disclosure Statement, which can kill or tank the deal by $10,000–$30,000.
Homeowner's insurance may deny a claim related to water damage from an improperly installed shower waterproofing assembly or electrical issue, costing $5,000–$15,000 out-of-pocket.
Lender (mortgage or HELOC) can require a retroactive permit or forced removal if work is discovered during appraisal or title review, delaying or blocking refinance.

Arnold, Missouri full bathroom remodel permits — the key details

Waterproofing and shower assembly details are critical and often spark rejections. If you're converting a bathtub to a shower (or renovating an existing shower), IRC R702.4.2 requires a continuous water-resistive barrier behind and under all interior wall surfaces in the shower. This typically means cement board or tile backer board (not drywall) with a membrane (Kerdi, RedGard, or equivalent) applied to all wall surfaces within the shower enclosure, extending at least 6 inches above the tub or shower pan rim and down to the pan subfloor. The pan itself must have a sloped floor (1/4 inch per foot toward the drain) and a waterproof pan liner or mortar bed. Arnold's inspector will ask to see the waterproofing specification on the plan — if you just say 'cement board and tile,' they'll ask for the membrane brand and thickness. Tile alone over drywall is a code violation and will be rejected. This is one of the top reasons remodels fail inspection. If you're just replacing tile in an existing shower (not gutting it), you may be exempt from the full waterproofing assembly requirement, but that's a gray area — call the department before starting.

Three Arnold bathroom remodel (full) scenarios

Scenario A

Tile and vanity swap, toilet in place — north Arnold ranch, 1998 home

You're replacing the old vinyl tile with new ceramic tile, removing the 30-inch vanity and installing a new 36-inch vanity in the same footprint, and swapping the old toilet and faucet for new models without relocating anything. The existing exhaust fan stays, the tub stays, no walls move. This is surface-only work. No permit required. You can hire a contractor or DIY this work. Your only headache is aesthetic: if the new vanity is wider, you may need to adjust the supply/drain lines by an inch or two to fit — but those are in-place adjustments, not a relocation, so still no permit. Cost: $3,000–$6,000 depending on tile grade and vanity choice. No permit fee, no inspections. Timeline: 3–7 days. Arnold's Building Department will not require a permit because you're not touching the plumbing or electrical circuits, and the waterproofing (if it exists) is staying in place.

Scenario B

Toilet relocation, new drain line, rear bathroom addition — south Arnold 1970s colonial, owner-builder

You're moving the toilet 6 feet to the opposite wall (the stud wall is being reframed to accommodate it). This requires a new 3-inch drain line, a new vent line (the old toilet vent is too far away now — more than 8 fixture-lengths), and a new supply line. You're not changing the bathtub, just the toilet. As the owner-builder (homeowner), you can pull the permit and do the rough plumbing yourself or hire a licensed plumber. Arnold's Building Department will require a plumbing permit ($200–$300 depending on valuation) and a site plan showing the new drain and vent routing. The inspector will rough-inspect the drain (checking slope and trap arm length), the vent (checking it terminates properly through the roof or wall), and the supply line (checking it's 1/2 inch copper or PEX and properly supported). You'll need to schedule inspections: one rough plumbing (after pipes are laid but before drywall), one final (after trim-out and fixtures are installed). Timeline: 3–4 weeks from permit pull to final inspection. If the vent line requires a new hole through the roof, you're looking at additional framing and roofing work — verify with the inspector during the pre-inspection conversation whether a new vent can go through an exterior wall instead (cheaper). Lead-paint rules apply (pre-1978 home), so the drywaller must either be RRP-certified or you must hire a certified renovator for $500–$1,000. Total cost: $8,000–$15,000 including permit, labor, and materials.

Scenario C

Tub-to-shower conversion, new exhaust fan, new GFCI circuit — master bath, 1995 home

You're removing the old bathtub and installing a walk-in shower in the same footprint. The new shower requires a cement-board and membrane waterproofing assembly (per IRC R702.4.2) — a full spec sheet detailing the membrane brand, thickness, and installation method must be submitted. You're also adding a new exhaust fan ducted to the roof (the old bathroom has only a small window). The fan requires a new 20-amp circuit from the breaker panel (wired by a licensed electrician), and a smooth-wall duct run to the roof with a damper. The plumbing drain can stay in the same location, but the trap arm and vent may need tweaking depending on the shower pan configuration — the inspector will verify this during rough plumbing. You need two permits: plumbing ($250–$350) and electrical ($150–$250). Plumbing will be rough-inspected after the pan is set and the drain is connected. Electrical will be rough-inspected after the fan and circuit are wired in the panel. The waterproofing assembly must be inspected before tile is installed — this is a separate 'wall assembly' or 'waterproofing' inspection that some smaller jurisdictions skip, but Arnold's inspector may request. Timeline: 4–5 weeks. If you do the drywall and cement-board work yourself, you can pull the plumbing permit as owner-builder, but the electrical work MUST be done by a licensed electrician and the permit holder. Total cost: $12,000–$22,000 depending on shower size, tile grade, and exhaust-fan duct routing.

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Why waterproofing assembly specification is the #1 rejection in Arnold bathroom remodels

Arnold's Building Department, like all jurisdictions, enforces IRC R702.4.2, which requires a continuous water-resistive barrier in all shower and tub enclosures. The code is prescriptive: you must use materials specifically rated for wet areas (cement board, fiber-reinforced concrete backerboard, waterproof drywall, or equivalent) with a water-resistive membrane (liquid-applied or sheet-applied). The membrane must cover all wall surfaces within the shower, extend at least 6 inches above the tub rim or shower base rim, and go down to the pan or floor substructure. Drywall alone is not acceptable. Many homeowners and even some contractors still think 'drywall plus lots of caulk' is enough — it is not, and Arnold's inspector will reject it.

The most common error is submitting a plan that says 'cement board and Kerdi membrane' without specifying thickness, application method, or sealing details. Kerdi sheets come in standard thickness (3/16 inch); if you're using a liquid-applied membrane like RedGard or Aqua Defense, you need two coats per manufacturer spec (typically 1.5 mm per coat). Arnold's examiner will ask you to clarify: Is it Kerdi sheets or liquid? If sheets, how are they sealed at seams (sealed with Kerdi-Fix or similar per manufacturer)? If liquid, what's the brand and how many coats? This back-and-forth adds 1–2 weeks to review. Avoid it by submitting a detailed specification sheet (downloaded from Schluter, Aqua Defense, or RedGard websites) with your permit application.

The second-most-common error is the shower pan. If you're installing a pre-fabricated fiberglass or acrylic pan, you're good — the pan itself is water-resistant. If you're using a mortar bed with a liner (tile-ready pan), you must specify the liner material (PVC, EPDM, or chlorinated polyethylene), thickness, and installation method. If you're doing a curbless or walk-in shower with a sloped mortar bed, the slope must be 1/4 inch per foot toward the drain, and the mortar bed must be sealed or lined to prevent water seepage to the subfloor. Arnold's inspector will ask to see the pan rough-in during the plumbing inspection to verify slope and drain connection. Get the pan detail right before you call for inspection — rework after failing inspection costs time and money.

For pre-1978 homes, lead-paint hazard assessment is required under EPA RRP. If your old bathtub or tile surround has paint or caulk that may contain lead, the work is considered 'renovation' and requires lead-safe practices: containment, HEPA vacuuming, and disposal at a licensed facility. This is not a building-code issue per se, but it's enforced during permit review if the home is pre-1978. Budget $500–$1,500 for a certified renovator or RRP-certified contractor to handle this. Many small bathroom remodels in Arnold are in 1970s–1990s homes, so this is not rare.

Exhaust fan duct routing: why 'venting to the attic' fails every time

Arnold's Building Department enforces IRC M1505.2, which mandates that bathroom exhaust fans must be ducted to the outside of the building (roof, wall, or soffit). Venting into the attic is not permitted. Why? Moisture from the bathroom condenses in the attic during winter and cold seasons, leading to mold, rot, and structural damage. Many homeowners and even some HVAC contractors cut corners here, especially if the bathroom is on an interior wall with difficult roof access. An attic vent seems cheaper and easier — it is not. Arnold's inspector will fail this during rough inspection and require you to relocate the duct to terminate through the roof or an exterior wall.

The code-compliant approach is smooth-wall metal duct (6 inches diameter for most residential fans), sloped downward at a minimum 1/4 inch per foot (preferably 1/2 inch per foot) so condensation drains back to the bathroom, not pooling in the duct. Flexible accordion-style duct is code-compliant only if it's not accessible and not used for long runs (more than 5–6 feet); metal duct is preferred. The duct terminates through the roof or exterior wall with a damper (check valve) that prevents outside air from backdrafting into the bathroom when the fan is off. The damper must be accessible for cleaning (lint buildup kills efficiency and is a fire hazard).

For a typical second-floor bathroom in Arnold, the easiest termination is straight up through the roof — a 6-inch or 7-inch roof cap with flashing, installed by a roofer or HVAC technician ($300–$600 labor). For a first-floor interior bathroom with no easy roof access above, running the duct to an exterior wall requires cutting a hole in rim joist and band board, adding a wall thimble, and installing a wall cap — this is also $300–$600 in labor. The duct itself is cheap ($50–$100 material). Plan for both during design; ask the building department during the pre-permit conversation whether roof or wall termination is preferred (some departments have a slight preference). Either way, specify it on the plan before you pull the permit.

A final note: the fan CFM rating must match the bathroom size. IRC M1505.4 requires 50 CFM for a bathroom with a toilet and sink, or 100 CFM for a bathroom with a toilet, sink, and tub/shower. If your bathroom is small (75 square feet), 50 CFM is enough. If it's large (150+ square feet), go for 100 CFM. Many homeowners buy an undersized fan to save money and are disappointed when moisture still lingers. Arnold's inspector will not fail you for oversizing (more CFM is always okay), only for undersizing or incorrect termination. The inspector may ask to see the fan spec sheet to verify CFM; have it ready.

City of Arnold Building Department
Arnold City Hall, 300 Jeffco Boulevard, Arnold, MO 63010 (verify address with city website)
Phone: (636) 282-7820 or local Arnold city office (confirm hours before visiting)
Monday–Friday, 8:00 AM–5:00 PM (call to confirm exact hours and closure dates)

Common questions

Can I do a full bathroom remodel myself in Arnold if I'm the homeowner?

Partially. As owner-builder, you can pull permits for plumbing and handle rough plumbing work (drain, vent, supply lines) yourself if you're proficient. Electrical work must be done by a licensed Missouri electrician — you cannot pull an electrical permit yourself. Drywall, tile, and cosmetic work have no license requirement. If you're unsure about any phase, hire a licensed contractor; the permit fee is the same either way.

How much does a bathroom remodel permit cost in Arnold?

Arnold charges $200–$500 depending on project valuation. A typical full-bath remodel valued at $15,000–$30,000 runs $250–$350 for a plumbing permit and $150–$250 for an electrical permit (if adding circuits or fans). Some cities charge a flat fee; Arnold bases fees on valuation. Call the Building Department to get an exact quote based on your scope and budget.

What's the difference between a bathroom remodel permit and a full-home renovation permit in Arnold?

A bathroom remodel permit covers only that room's plumbing, electrical, and structural changes. A full-home renovation or substantial remodel permit (triggered if you're renovating more than 25% of a home's surface area) requires a different application and may include energy code, HVAC, and insulation reviews. For a single-bathroom project, you'll pull a bathroom remodel permit, not a whole-house permit. Check with Arnold if your project spans multiple rooms or includes HVAC work.

Do I need a lead-paint inspection if my Arnold home was built in 1978?

If the home was built in or before 1978, EPA RRP lead-safe renovation rules apply to any work that disturbs paint or caulk (e.g., removing old tile or tub surrounds). You must either hire a certified renovator or have a licensed contractor perform the work under RRP protocols. This is not a building-permit issue, but it is a legal requirement and will be discussed during permit review. Budget $500–$1,500 for RRP compliance.

Can I use drywall instead of cement board in my shower?

No. IRC R702.4.2 (enforced by Arnold) requires cement board, tile backer board, fiber-reinforced concrete board, or waterproof drywall (not standard drywall) in all shower enclosures, paired with a water-resistive membrane. Drywall alone is a code violation and will be rejected on inspection. Use cement board or equivalent and apply a membrane (Kerdi, RedGard, or similar) per manufacturer spec.

What happens if I convert a tub to a shower without a permit?

The conversion changes the waterproofing assembly configuration and may require new drain/vent routing. If discovered during a home sale or inspection, it will be flagged as unpermitted work, require a Seller's Disclosure, and can tank a sale or cost $10,000–$30,000 in price reduction. Arnold's inspector will also fail you if caught and require a retroactive permit plus double fees to bring the work into compliance. Always pull a permit for tub-to-shower conversions.

How long does plan review take for a bathroom remodel in Arnold?

Arnold typically takes 2–3 weeks for initial plan review and 5–7 business days for a resubmittal if corrections are needed. Once approved, inspections are usually scheduled within 2–3 business days. Total timeline from permit pull to final inspection: 4–6 weeks depending on how many resubmittals are needed. Expedited review is not typically available for small projects.

Do I need a separate permit for a new exhaust fan, or is it included in the bathroom remodel permit?

A new exhaust fan requires electrical work (new circuit) and mechanical work (ductwork), which are covered under the bathroom remodel electrical permit. You don't pull a separate 'exhaust fan permit.' However, if the ductwork is complex or requires structural work (e.g., reroofing around a new vent), the plumbing or general permit may reference it. Discuss with the Building Department during permit submission if you're uncertain.

What inspections do I need for a full bathroom remodel in Arnold?

Typically: (1) Rough plumbing (after drain/vent/supply are installed but before walls close); (2) Rough electrical (after new circuits and fan are wired in the panel); (3) Waterproofing assembly (if doing a shower, some jurisdictions inspect before tile; Arnold may require this); (4) Final inspection (after all work is complete and fixtures are installed). Not all jurisdictions require waterproofing inspection — call ahead to confirm Arnold's requirement.

Can I use PVC for drain lines in a bathroom remodel in Arnold?

Yes, PVC is code-compliant for drain lines (DWV, or drain-waste-vent) under IRC P3002. PVC is widely used and cheaper than cast iron or copper. Ensure proper slope (1/4 inch per foot), correct trap depth, and proper vent connection. The inspection will verify these details. PVC is allowed for both interior and exterior underground use (with appropriate UV protection if exposed outdoors, though that's uncommon for bathroom drains).

Disclaimer: This guide is based on research conducted in May 2026 using publicly available sources. Always verify current bathroom remodel (full) permit requirements with the City of Arnold Building Department before starting your project.

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