Tub-to-Shower Conversion Permits in Boise
A complete guide to permit requirements, fees, inspections, and plumbing code regulations for tub-to-shower conversions in Boise, Ada County, and the Treasure Valley. Every conversion requires a plumbing permit — here is exactly why and what to expect.
Unlike some shower remodels where cosmetic-only work may be permit-exempt, tub-to-shower conversions in Boise always require at least one permit. The fundamental reason is that the bathtub drain and the shower drain occupy different positions, use different trap configurations, and require different slope specifications. Moving the drain is a plumbing modification that must be permitted and inspected under the International Plumbing Code (IPC) as adopted by Idaho.
Always Requires a Permit
Every tub-to-shower conversion involves at least one of these permit-triggering modifications. In most conversions, several apply simultaneously.
Drain relocation (required in every conversion)
The bathtub drain is positioned at the end of the tub, while the shower drain must be centered or positioned along the entry edge. This means the drain pipe, P-trap, and waste line connection must all be modified — a plumbing permit is required.
Supply line modifications
The shower valve and showerhead supply lines typically move to different positions than the existing tub faucet and shower riser. Adding a rain showerhead, handheld wand, or body sprays requires additional supply runs.
P-trap reconfiguration
Bathtub P-traps and shower P-traps differ in size, position, and connection angle. The existing tub trap must be removed and a new shower trap installed at the correct depth and orientation per the IPC.
Vent pipe modifications
If the drain relocation moves the trap more than 5 feet from the existing vent connection, the vent pipe may need to be extended or reconfigured to maintain proper drainage and prevent siphoning.
Exhaust fan or lighting additions
Adding or upgrading an exhaust fan, installing in-shower lighting, or adding a heated floor system requires an electrical permit. Walk-in showers produce more airborne moisture than tub/shower combos, so fan upgrades are common.
Structural changes for curbless entry
A curbless (zero-threshold) conversion requires lowering the subfloor in the shower area and may involve modifying floor joists. This triggers a building permit and potentially structural engineering review.
No Additional Permit Needed
These components of a tub-to-shower conversion are covered by the main permits and do not require separate permits of their own.
Tile installation on walls and floor
Installing tile, stone, or solid surface panels on the shower walls and floor is cosmetic finish work. Waterproofing membrane installation is also included in this category and does not require a separate permit.
Glass enclosure installation
Installing a frameless glass door, fixed splash panel, or sliding glass enclosure is not a permit-triggering activity. The enclosure is a finish element installed after all permitted work passes inspection.
Replacing fixtures at the new valve location
Once the plumbing rough-in is inspected and approved, connecting the showerhead, mixing valve trim, and drain cover are finish steps that do not require additional permits.
Installing grab bars, niches, and accessories
Surface-mounted grab bars, built-in tile niches (if within the already-inspected waterproof assembly), soap dishes, and towel bars are accessory installations that do not require permits.
Painting and trim work
Painting the bathroom walls, installing baseboards, and other cosmetic finish work around the new shower are not permit-triggering activities.
Bathtub demolition and removal
Removing the existing bathtub, hauling away debris, and preparing the alcove for the new shower construction is demolition work that does not require a separate permit in Boise.
Key distinction: A standard shower remodel where the existing plumbing stays in place may not require permits. A tub-to-shower conversion, however, always requires at least a plumbing permit because the drain location physically changes. There are no exceptions to this in Boise, Ada County, or any Treasure Valley municipality. Iron Crest Remodel determines the exact permits needed during our design phase and handles every application and inspection on your behalf.
The permit process for tub-to-shower conversions follows a predictable four-step sequence. Whether your home is within Boise city limits, in unincorporated Ada County, or in surrounding cities like Meridian, Eagle, or Garden City, the general process is consistent. Iron Crest Remodel manages every step on your behalf so you never need to visit the permit office.
Application Submission
Iron Crest prepares and submits the permit application to the City of Boise Planning & Development Services or Ada County Development Services, depending on your property's jurisdiction. Applications can be submitted through the City of Boise's ePermit portal or Ada County's online system.
Required documentation: Completed application form, project scope description, plumbing plan showing existing tub drain location and proposed shower drain location, supply line routing, electrical plan (if applicable), waterproofing specifications, and the contractor's license number and proof of insurance. For curbless conversions, structural engineering drawings showing joist modifications are also required.
Plan Review
A plan reviewer examines the submitted documents for compliance with the International Residential Code (IRC) and the International Plumbing Code (IPC) as adopted by Idaho. For tub-to-shower conversions, the review focuses on drain sizing and slope, P-trap configuration, vent connection distance, supply line sizing for any additional fixtures, and waterproofing specifications.
Timeline: Standard plumbing-only permits are typically reviewed in 5 to 10 business days. Simple conversions may receive over-the-counter approval in 1 to 3 days. Projects with structural modifications (curbless conversions) may take 2 to 3 weeks due to the engineering review component.
Permit Issuance & Construction
Once plans are approved, the permit is issued and construction can begin. The permit card must be posted at the job site in a visible location (typically on a window or door visible from the street). Permits in Boise are valid for 180 days from the date of issuance. If construction does not begin within 180 days, the permit expires and must be renewed. Iron Crest coordinates the construction start date with the permit approval to avoid any gaps or delays in the project schedule.
Inspections & Final Approval
Inspections are scheduled at specific stages of construction (detailed in the inspections section below). The contractor requests inspections by calling or using the online portal, typically with 24-hour advance notice. Inspectors visit the site, verify compliance with the approved plans and applicable codes, and either approve the work or require corrections. After all final inspections pass, the permit is closed and a certificate of completion is issued for your records. Iron Crest never covers any rough-in work (with waterproofing, tile, or other finish materials) until the corresponding inspection has passed.
A tub-to-shower conversion may require one, two, or three separate permits depending on the scope of work. The plumbing permit is required for every conversion. Electrical and building permits are triggered by specific upgrades or design choices.
Plumbing Permit
Required for every conversion
This is the permit that makes tub-to-shower conversions different from standard shower remodels. Because the drain must physically move from the tub position to the shower position, a plumbing permit is mandatory in every case.
- Drain relocation from tub position to shower position (center or linear)
- P-trap replacement and reconfiguration for new drain location
- Supply line modifications for new shower valve position
- Vent pipe extension if trap-to-vent distance exceeds code limits
- Anti-scald valve installation per IRC Section P2708.4
Electrical Permit
Required if adding electrical components
Many tub-to-shower conversions include electrical upgrades beyond the basic plumbing work. Since walk-in showers produce more airborne moisture than tub/shower combos, exhaust fan upgrades are especially common.
- Exhaust fan installation or upgrade (minimum 50 CFM per IRC, 80–110 CFM recommended)
- Recessed in-shower lighting (wet-rated IC-rated fixtures required)
- Electric radiant floor heating mats (dedicated GFCI circuit required)
- LED niche lighting or accent lighting circuits
- GFCI protection for all bathroom circuits per NEC 210.8(A)
Building Permit
Required for structural modifications
A building permit is triggered when the conversion involves structural changes to the home. The most common trigger is a curbless shower conversion that requires subfloor lowering or floor joist modification.
- Subfloor lowering for curbless (zero-threshold) shower entry
- Floor joist notching or reinforcement for drain routing
- Removing a wall or expanding the alcove beyond the original footprint
- Adding or enlarging a window within the shower area
- Structural engineering review may be required for joist modifications
Multiple permits are common: A typical tub-to-shower conversion with an exhaust fan upgrade requires both a plumbing permit and an electrical permit. A curbless conversion with new lighting and heated flooring may require all three. Iron Crest Remodel determines the exact permits needed during our planning phase and handles every application, fee, and inspection on your behalf.
Permit fees are a small but necessary part of your conversion budget. Here are the typical fees you can expect in the Boise and Ada County area. Iron Crest Remodel includes all permit fees in your project estimate — no hidden charges or surprise costs.
| Permit Type | Typical Fee | When Required |
|---|---|---|
| Plumbing Permit | $75 – $200 | Every tub-to-shower conversion (drain relocation, supply line changes) |
| Electrical Permit | $75 – $200 | Exhaust fan, in-shower lighting, heated floor, niche LED circuits |
| Building Permit | $150 – $400 | Curbless conversion with subfloor modification or wall removal |
| Plan Review Fee | 65% of permit fee | Added to building permit fee for structural plan review |
| Structural Engineering | $300 – $800 | Curbless conversions requiring joist modification calculations |
Standard curbed conversion total: $150 – $400 in permit fees for a typical conversion involving a plumbing permit and, if electrical upgrades are included, an electrical permit. This covers the vast majority of tub-to-shower conversions in the Boise area.
Curbless conversion total: $400 – $1,200 in permit and engineering fees including a building permit with structural plan review, plumbing permit, electrical permit, and structural engineering calculations. The building permit and engineering review account for the majority of the cost due to the structural modifications involved.
Each permitted tub-to-shower conversion requires inspections at defined stages of construction. All rough-in inspections must pass before the work is covered with waterproofing membrane, tile, or other finish materials. Iron Crest schedules every inspection proactively and never covers rough-in work before it passes inspection.
Rough-In Inspections
Rough-in inspections occur after the plumbing, electrical, and structural work is complete but before any finish materials (waterproofing, backer board, tile) are installed. The inspector must be able to see all pipes, wiring, and framing.
Rough Plumbing Inspection
Inspects the new shower drain line, P-trap installation, supply line routing, valve placement, and vent connections. The inspector verifies that the drain pipe has the correct slope (1/4 inch per foot minimum for horizontal runs), the P-trap is the correct size and orientation, and all supply connections are pressure-tested with no leaks. This is the most critical inspection in a tub-to-shower conversion.
Rough Electrical Inspection(If applicable)
Examines all new wiring for exhaust fans, lighting circuits, heated floor connections, and GFCI protection. Wire gauge, junction box placement, circuit breaker sizing, and grounding connections are verified. Required only when electrical work is part of the conversion.
Framing / Structural Inspection(If applicable)
Required only for curbless conversions involving subfloor modification or joist work. Verifies that structural changes match the approved engineering drawings, including joist reinforcement, blocking, and subfloor preparation for the lowered shower pan area.
Final Inspections
Final inspections occur after all finish work is complete. The inspector verifies that all fixture connections function correctly, there are no leaks, and the completed work matches the approved plans.
Final Plumbing Inspection
Tests all fixture connections (showerhead, mixing valve, drain), verifies no leaks under pressure, tests drainage flow rate, and confirms the anti-scald valve operates correctly. The inspector also verifies hot and cold supply is connected to the correct valve ports. This inspection occurs after tile, glass, and all fixtures are installed.
Final Electrical Inspection
Tests all circuits including GFCI protection (required for all bathroom receptacles and in-shower lighting per NEC), exhaust fan operation and CFM rating, heated floor thermostat function, and proper grounding. Required only when electrical work was part of the project.
Final Building Inspection
A comprehensive final review verifying that all work matches the approved plans, all trade inspections have passed, and the completed shower meets code requirements. After this inspection passes, the permit is closed and a certificate of completion is issued for your permanent records.
Some homeowners wonder why a tub-to-shower conversion can't be treated as a simple cosmetic update. The answer lies in three fundamental plumbing differences between bathtubs and showers that require code-compliant modifications and inspections.
Drain Relocation
Bathtub drains are typically located at one end of the tub, near the wall. Shower drains must be positioned at the center of the shower floor (for center drains) or along the entry edge (for linear drains). The waste pipe running under the subfloor must be rerouted to the new drain position, which involves cutting into the subfloor, modifying the drain pipe slope, and reconnecting to the main waste stack.
The drain pipe must maintain a minimum 1/4-inch-per-foot slope toward the main waste stack. Insufficient slope causes slow drainage and potential backups. Excessive slope causes water to outrun solid waste, leading to pipe blockages over time.
Supply Line Changes
A bathtub faucet mounts near the foot of the tub at a low height. A shower valve mounts at 48 to 52 inches from the finished floor on the back wall or a side wall. The hot and cold supply lines must be rerouted from the old tub faucet position to the new shower valve position. If additional fixtures are added (rain showerhead, handheld, body sprays), additional supply runs are needed.
The new shower valve must include an anti-scald (pressure-balance or thermostatic) mechanism per IRC Section P2708.4, which limits maximum water temperature to 120°F at the showerhead outlet.
P-Trap Modifications
The P-trap is the curved pipe section beneath the drain that holds water to prevent sewer gas from entering the home. Bathtub P-traps and shower P-traps differ in size, depth, and orientation. A standard bathtub uses a 1-1/2-inch P-trap with specific depth and horizontal offset requirements. A shower uses a 2-inch P-trap that must be installed at the correct depth below the shower drain to maintain the water seal.
An improperly sized or positioned P-trap can lose its water seal through evaporation or siphoning, allowing sewer gas to enter the bathroom. This is one of the primary reasons the plumbing rough-in inspection is mandatory.
The bottom line: A tub-to-shower conversion is not a cosmetic update — it is a plumbing modification that changes the drain location, supply line routing, and trap configuration. These changes affect the safety and integrity of your home's plumbing system and must be inspected to ensure compliance with building codes. Working with a licensed contractor who handles all permits ensures the work is done correctly and creates a documented record that protects your investment and home value.
Tub-to-shower conversions raise specific permit and code questions that homeowners frequently ask. Here are the scenarios we encounter most often and what you need to know.
Unpermitted Conversions & Resale
Boise-area real estate agents report that unpermitted tub-to-shower conversions are one of the most commonly flagged issues during home sales. Home inspectors know that a shower where a tub used to be means plumbing was modified, and they check permit records through the City of Boise's online portal. If no permit exists, the buyer's lender may require the work to be retroactively permitted and inspected before closing — potentially requiring tile and waterproofing to be removed so the plumbing can be examined. This can delay a sale by weeks and cost thousands of dollars to resolve.
Insurance Coverage Implications
Homeowner's insurance policies in Idaho typically exclude coverage for damage caused by unpermitted work. If an unpermitted tub-to-shower conversion results in a water leak that damages the subfloor, adjacent rooms, or the floor below, your insurance company can deny the claim on the basis that the plumbing modification was not permitted or inspected. Given that water damage from shower leaks can easily cost $5,000 to $20,000 or more to repair, the $150 to $400 permit fee is a small investment in protecting your home and financial interests.
HOA & Condo Conversions
If you live in a Boise-area condominium or a neighborhood with an HOA, a tub-to-shower conversion may require HOA approval in addition to the city or county permit. Some HOAs have architectural review committees that must approve exterior plumbing vent modifications or any work that could affect shared walls, floors, or plumbing stacks. In multi-story condos, the drain relocation may affect the unit below, requiring coordination with the building management and potentially the downstairs unit owner.
Permit for Second-Story Conversions
Tub-to-shower conversions on the second floor of a Boise home involve the same permit requirements as first-floor conversions, but with additional considerations. The drain pipe runs through the first-floor ceiling, making proper slope and leak-free connections even more critical. Curbless conversions on the second floor require careful waterproofing of the entire shower floor to prevent leaks into the room below. The plumbing inspector pays particular attention to second-story installations because a failure has greater consequences than a slab-on-grade or crawl space installation.
Common questions about permits for tub-to-shower conversions in Boise and Ada County.
Do I always need a permit for a tub-to-shower conversion in Boise?
Yes. Unlike some shower remodels that may be cosmetic-only, a tub-to-shower conversion always requires at least a plumbing permit in Boise, Ada County, and all Treasure Valley municipalities. The reason is straightforward: the bathtub drain and the shower drain are in different positions, use different trap configurations, and require different slope specifications. Relocating the drain from the tub position to the shower position constitutes a plumbing modification that must be permitted and inspected to ensure it meets the International Plumbing Code (IPC) as adopted by Idaho.
How much do tub-to-shower conversion permits cost in the Boise area?
Permit fees for a tub-to-shower conversion in Boise typically range from $150 to $500 total depending on the scope of work. A plumbing permit costs $75 to $200 (required for every conversion). An electrical permit costs $75 to $200 if you are adding an exhaust fan, new lighting, or heated flooring. A building permit costs $150 to $400 if structural modifications are needed for a curbless entry. Plan review adds approximately 65% of the building permit fee. Iron Crest Remodel includes all permit fees in your project estimate.
What happens if I do a tub-to-shower conversion without a permit?
Unpermitted tub-to-shower conversions in Boise carry significant consequences. If the work is discovered during a home sale, the city can require you to open finished walls and tile for inspection, obtain retroactive permits at higher cost, or potentially demolish and redo non-compliant plumbing work. Unpermitted plumbing modifications can void your homeowner’s insurance coverage for water damage claims. Title companies and home inspectors in the Boise market routinely compare building permit records against visible bathroom modifications and will flag unpermitted conversions.
How long does the permit process take for a tub-to-shower conversion?
Standard plumbing permits for tub-to-shower conversions in Boise are typically reviewed within 5 to 10 business days. Simple conversions with only a plumbing permit may be issued over the counter in 1 to 3 days. Projects involving structural modifications for curbless entries or significant electrical additions may take 2 to 3 weeks for plan review due to the structural engineering requirements. Iron Crest submits complete applications with all required documentation on the first submission to avoid revision delays.
Does Iron Crest Remodel handle the permits for tub-to-shower conversions?
Yes. We handle the entire permit process as part of every tub-to-shower conversion project. This includes determining which permits your specific project requires (plumbing, electrical, building, or a combination), preparing all required drawings and plumbing plans, submitting the application to the City of Boise or Ada County, paying permit fees (included in your project cost), scheduling all required inspections at the correct construction stages, and meeting with inspectors on-site. You never need to visit the permit office or coordinate inspections yourself.
Explore our complete library of tub-to-shower conversion guides and permit resources for Boise homeowners.
The following government agencies, industry organizations, and official resources provide additional information relevant to your remodeling project.
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