Bathroom Remodel Permit in Montgomery, IL (2026)

Research by DoINeedAPermit Research Team · Updated May 2026

The Short Answer

A full bathroom remodel requires a permit in Montgomery if you relocate any plumbing fixture, add electrical circuits, install a new exhaust fan duct, convert a tub to shower, or move walls. Surface-only work—like replacing a toilet, vanity, or faucet in place—is typically exempt.

Montgomery's Building Department applies the 2021 Illinois Energy Conservation Code (which adopts the 2021 IRC) with local amendments that reflect the city's glacial-till soil conditions and the specific frost-depth requirements for the northern Illinois zone (42 inches in the Chicago metro area where Montgomery sits). Unlike some neighboring communities that grandfather older homes on septic systems or have lenient owner-builder exemptions, Montgomery enforces plumbing-relocation permits strictly because of the region's challenging subsurface drainage—frost heave and clay-layer settling have historically caused drain-line failures when improper slope or trap-arm length is installed. The city's online permit portal (accessed through the City of Montgomery website) requires digital submission of sealed plumbing and electrical plans for any fixture move; in-person plan review is still available but discouraged, and the typical turnaround is 10-14 business days for a bathroom remodel. Montgomery also requires GFCI/AFCI certification on all bathroom circuits and enforces IRC M1505 exhaust-fan ducting rules strictly—flex duct termination indoors or improperly sized ductwork is a common rejection. Your cost basis for permit fees is typically the estimated project cost; Montgomery charges roughly 1.5–2% of valuation, meaning a $15,000 remodel runs $225–$300 in permit fees, plus separate electrical and plumbing contractor licenses if you hire out.

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

Stop-work orders issued by Montgomery Building Department can result in $250–$500 daily fines, plus forced closure of permits and mandatory re-inspection once corrected.
Insurance claim denial: your homeowner's policy may refuse to cover water damage or electrical injury if unpermitted work caused the loss, costing $10,000–$50,000+ out of pocket.
Home sale complication: Illinois Residential Property Disclosure Act requires sellers to disclose permit violations; unpermitted bathroom work triggers a TDS (Residential Real Property Disclosure Statement) flag and can reduce sale price by 5–15%.
Lender refinance block: if you refinance or file a home-equity line of credit after unpermitted work, appraisers and title companies often flag it, delaying or killing the transaction.

Montgomery bathroom remodels — the key details

Montgomery, located in DuPage County's northwest corridor, sits in IECC Climate Zone 5A (northern Illinois) with a frost depth of 42 inches—a critical factor for any plumbing work that touches drain lines or supply piping in the foundation or crawl space. The 2021 IRC Section P2706 governs drainage-fitting selection and trap-arm length; when you relocate a toilet, sink, or shower drain, the trap arm (the run of pipe from the trap to the vent) cannot exceed 6 feet of length or 6 feet of developed length if traveling horizontally first. Montgomery's clay-rich glacial-till soil (common across DuPage County) is prone to settling and frost heave, which means improper slope or unsupported drain runs often fail within 3–5 years. The Building Department requires sealed plumbing plans showing the new drain routing, slope (minimum 1/4 inch per foot), and trap-arm length for any fixture relocation. Many DIY-minded homeowners underestimate this: a full bathroom gut that moves the toilet or shower to a new wall often requires a new vent stack or horizontal vent run, which can cost $2,000–$4,000 in labor and material alone and is non-negotiable under code.

Electrical work in Montgomery bathrooms is governed by the 2021 NEC (National Electrical Code), Section 210.8, which mandates GFCI (ground-fault circuit interrupter) protection on all outlets within 6 feet of the sink, tub, or shower—and AFCI (arc-fault circuit interrupter) protection on all branch circuits serving the bathroom. If you're adding a new exhaust fan or recirculating lighting, you may need a new 20-amp circuit dedicated to bathroom exhaust and ventilation. The permit application must include a one-line electrical diagram or a photo of the existing panel with the proposed new breaker location clearly marked. Montgomery's inspectors will verify GFCI/AFCI type and placement during the rough-electrical inspection, typically scheduled within 5 business days of permit issuance. Common rejection: submitting a permit with a cheap outlet strip or claiming an existing circuit 'has room' without showing the panel load. The Building Department will require a licensed electrician to sign off if you're adding circuits; owner-builder exemptions in Montgomery apply to owner-occupied work, but only for the labor—the electrical design and permit paperwork must still be code-compliant and often reviewed by a licensed electrician even if the homeowner pulls the permit themselves.

Shower and tub waterproofing is a high-bar requirement under IRC R702.4.2 and is one of the most common rejection points in Montgomery bathroom permits. If you're converting a tub to a shower or installing a new shower enclosure, you must specify the waterproofing assembly: either a mortar base with a PVC or CPE membrane (the traditional approach), or a modern alternative like a schluter drain with a waterproof membrane and alkali-resistant mesh tape over drywall. Montgomery's plan-review checklist explicitly requires a written waterproofing specification and often wants to see product data sheets for the membrane, sealants, and any prefabricated systems (such as Kerdi or Wedi boards). Tile alone is not a waterproof barrier; water will wick through grout and behind tile within months if the substrate is not membrane-protected. Inspectors will schedule a framing/waterproofing inspection before drywall goes up, and a final inspection after tile is set. Budget for this: a proper waterproofing assembly in a 5x8 foot shower costs $1,500–$3,000 in material and labor, and shortcuts here will result in permit rejection or (worse) mold and structural damage within 2–3 years.

Exhaust ventilation is mandated by IRC M1505: bathrooms must have either a mechanical exhaust fan ducted to the outside (minimum 50 cubic feet per minute for a bathroom, 100 CFM if there's a whirlpool tub) or an operable window of at least 5% of the floor area. Montgomery enforces this strictly. The duct must terminate at least 10 feet away from any operable window, door, or air intake, and cannot be vented into the attic or a soffit—a common code violation that inspectors catch immediately. If your bathroom is on an upper floor or interior to the home, ductwork will run 20–40 linear feet and must slope downward toward the exterior exit; horizontal runs must slope slightly to prevent condensation pooling. Undersized ductwork (e.g., 4-inch flex duct for a 100-CFM fan) will be rejected. Submit a ductwork diagram with the permit showing routing, diameter, and exterior termination location. Many contractors try to save money by ducting into a shared soffit or attic—don't do this in Montgomery. The plan-review stage will flag it, and the rough-electrical inspection will include a duct-routing check.

Permitting workflow in Montgomery typically unfolds over 3–5 weeks: (1) submit plans and permit application via the online portal or in-person at City Hall; (2) plan review by the Building Department (10–14 business days, often with one round of comments); (3) permit issuance and fee payment; (4) rough plumbing, electrical, and framing inspections (typically within 5–10 days of scheduling); (5) final inspection after all finishes are complete. If you hire licensed contractors (plumber, electrician), they often handle permit paperwork; if you're the owner-builder, you'll need to coordinate inspections yourself and ensure the general contractor or subs are present. Montgomery's Building Department can be reached at City Hall; phone and hours are typically Mon–Fri 8 AM–5 PM, though it's wise to call ahead to confirm. Plan for inspections to take 30–60 minutes each. If you fail any inspection (e.g., waterproofing not sealed, ductwork not sloped, GFCI not installed), you'll need to correct the work and reschedule—adding 1–2 weeks to the timeline. Budget-wise, a typical full bathroom remodel in Montgomery runs $15,000–$40,000; permit fees are roughly $225–$400, plus contractor licensing (if applicable). Don't rush the inspections or skip the waterproofing spec—these are the two biggest failure points.

Three Montgomery bathroom remodel (full) scenarios

Scenario A

Toilet and vanity swap in place, new tile flooring — Stevenson Ranch mid-century ranch

You're replacing an existing toilet and pedestal sink with new matching fixtures in the exact same locations, and installing new ceramic tile over the existing vinyl flooring. No plumbing lines are being relocated, no new electrical circuits are added (the existing GFCI outlet remains in place), and no walls are moved. Under Montgomery code, fixture replacement in place is exempt from permitting as long as you're not touching water supply lines or drain lines. The toilet rough-in distance to the wall (typically 12 inches) should remain the same, and the sink drain can connect to the existing trap. New tile flooring over a solid subfloor (concrete slab or a well-established wood floor) requires no permit because you're not modifying the structure or systems. However, if the existing flooring is soft or slopes toward the drain, the inspector (if one were required) would flag it—so make sure your subfloor is solid and level before tiling. Total cost: materials $2,500–$4,500 (tile, fixtures, labor), zero permit fees. Timeline: 5–7 days if you hire a tile contractor and a plumber for final connections. No inspections required. This is the 'lowest-barrier' bathroom refresh.

No permit required (fixture replacement in place) | Existing GFCI outlet adequate | New tile over sound subfloor | $2,500–$4,500 total cost | Zero permit fees

Scenario B

Tub-to-shower conversion, relocated drain, new exhaust duct — Colonial-era home in downtown Montgomery

Your 1980s colonial has a master bathroom with a tub against the north wall; you want to gut it and install a walk-in shower on the east wall (moving the drain about 8 feet), add a new recessed exhaust fan with 40 linear feet of 6-inch flex ductwork vented through the roof, and install a ceiling-mounted light with AFCI protection. This is a full permit trigger: (1) plumbing relocation (drain moved to new wall), (2) new exhaust duct (IRC M1505), (3) new electrical circuit (AFCI). Montgomery requires a sealed plumbing plan showing the new trap location, trap-arm length (must be under 6 feet), and slope (1/4 inch per foot minimum). The existing tub's trap and vent are on the north wall; the new shower drain on the east wall will need either a new 3-inch vent stack (if the new trap is more than 6 feet from the existing vent) or a horizontal vent run (slope upward) that ties into the existing vent—this is the key cost driver and often requires opening walls to route the vent. Your plan must include a waterproofing spec: a cement board base with a PVC membrane and tile, or a Schluter-Kerdi system with membrane tape. The exhaust ductwork plan must show 6-inch smooth duct (not flex), sloped downward, terminating through the roof with a damper and a rain hood at least 10 feet from any window or air intake. Electrical plan must show a new 20-amp circuit dedicated to the exhaust fan and light (on the same circuit is allowed), with AFCI protection on the breaker. The electrical subpanel is typically in the basement or garage on a colonial; verify capacity before designing the circuit. Permit fee: roughly $350–$500 based on a $18,000–$25,000 project valuation. Timeline: plan review 10–14 days, then rough plumbing/electrical inspection (often combined), framing/waterproofing inspection, and final inspection—total 4–6 weeks. The waterproofing inspection is critical; expect the inspector to verify the membrane is sealed before drywall. Common rejections: trap-arm length over 6 feet (requires redesign), ductwork terminating in soffit, PVC membrane not sealed at corners, AFCI missing or wrong type. Budget: materials and labor roughly $18,000–$25,000 (tile, plumbing rework, ductwork, electrical circuit), permit fees $350–$500, plus any structural work if walls or joists are cut.

Scenario C

Double vanity, new mirror with lights, wall relocation — post-war suburban cape in Concord Township

Your 1950s cape has a small powder room (3x5 feet) with a single sink on the south wall. You want to remove the wall between the powder room and the adjacent closet, creating a 6x5 foot bathroom, and install a double vanity (two sinks on the west wall) with a new mirror-mounted LED fixture with integrated lights, and a toilet repositioned to the north wall. This involves (1) wall relocation (structural review required), (2) plumbing relocation (second sink drain, toilet trap moved), and (3) electrical changes (new circuit for the mirror lights). In Montgomery, any wall removal requires structural review by the Building Department, even if it's non-load-bearing; they'll want to verify the wall is indeed non-load-bearing via a framing plan or a structural engineer's letter. Load-bearing walls require an engineer and a header installation. The plumbing work: the existing sink trap and vent are on the south wall; adding a second sink on the west wall requires either a new trap and vent (tying into the existing vent stack or new vent if the trap arm exceeds 6 feet) or a wet-vented secondary drain. The toilet on the north wall will need a new 3-inch rough-in; if the existing vent is on the south wall, you may need to run a new vent up the north wall or a horizontal vent that slopes back to the main vent—this often requires opening the wall above the ceiling to route the vent, adding cost and time. Electrical: the mirror lights will need a new 15-amp circuit with GFCI protection (they're over a sink) and AFCI protection on the breaker; likely you'll add this to the existing bathroom circuit if there's capacity, or pull a new circuit from the panel. Permit: $300–$600 based on a $15,000–$20,000 valuation. Required plans: (1) floor plan showing wall removal and fixture locations, (2) structural note confirming non-load-bearing or engineer's letter, (3) plumbing schematic with trap-arm lengths and vent routing, (4) electrical one-line showing the new circuit. Timeline: plan review 10–14 days (may be longer if the structural status is questioned), then a framing inspection (walls open, verify structural is per plan), a rough plumbing and electrical inspection, and a final inspection—total 5–7 weeks. Common rejection in Montgomery: trap-arm length over 6 feet without a new vent stack (requires redesign), wall removal proposed without structural documentation, vent routing unclear, GFCI/AFCI missing on the light fixture circuit. Budget: materials and labor $15,000–$20,000 (drywall, plumbing rework, vent routing, double vanity, fixture, electrical), permit fees $300–$600, plus structural engineer if needed ($400–$800).

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Why Montgomery's glacial-till soil makes drain-slope code so critical

DuPage County, where Montgomery sits, is underlain by glacial till—a dense, clay-rich layer left by the last ice age. When you excavate a trench for a drain line in Montgomery's soil, you're working with clay that holds moisture and settles unevenly over time. Frost heave in winter (the ground freezes at 42 inches down in northern Illinois) can lift and tilt drain piping by 1–2 inches over a few seasons, causing pooling and backups. This is why the 2021 IRC Section P3005 mandates a minimum 1/4-inch slope per foot for all sanitary drains—and why Montgomery's Building Department and inspectors are strict about it.

When you relocate a toilet or shower in Montgomery, the permit review will scrutinize the slope calculation: if you run 20 feet of 3-inch PVC from a new toilet to the main stack, the elevation drop must be at least 20 × 0.25 = 5 inches. Many DIY plans or contractor sketches fail to show this; they draw a horizontal line from the new fixture to the stack and assume gravity will work. Under the frost heave and settling typical in DuPage County soil, a level or nearly-level drain will fail within 3–5 years. Montgomery inspectors will verify slope during the rough-plumbing inspection with a level or transit; if it's off by more than 1/8 inch per 10 feet, they'll reject it and require the contractor to re-slope or re-route.

The cost of getting this wrong: a clogged drain buried under your finished bathroom requires excavation, saw-cutting concrete, and a full rework—$4,000–$8,000. The permit fee upfront ($300–$500) is cheap insurance. If you're hiring a plumber, make sure they understand DuPage County soil conditions and don't just eye-ball the slope. Submit a elevation drawing on your permit plan, even if the inspector doesn't strictly require it; it shows competence and speeds plan review.

Waterproofing assembly rejection: what Montgomery inspectors actually check

Montgomery's Building Department uses a waterproofing checklist derived from IRC R702.4.2 and the International Residential Code's appendix on bathrooms. When you submit a permit for a shower remodel, the plan-review stage will require you to specify the waterproofing system—not just 'tile,' but the full assembly: base (mortar, cement board, Schluter pan, etc.), membrane (PVC, CPE, Kerdi, etc.), sealant, and finishing layer. Many homeowners think tile and grout is enough; it's not. Tile is porous, and grout is permeable. Water wicks through both within weeks if there's no membrane beneath.

Common rejection in Montgomery: the applicant submits a sketch showing 'tile shower' with no spec. The plan reviewer sends back comments: 'Specify waterproofing membrane type, product name, and sealant details.' If you use a traditional mortar bed with a PVC membrane, the plan must note: mortar base (thickness, slope), PVC membrane (mil thickness, seams sealed with PVC seaming compound), sealant (polyurethane or silicone brand), grout type, and tile. If you use a Schluter-Kerdi system (a popular modern approach), the spec should list the Kerdi board dimensions, Kerdi membrane, Kerdi drain, and sealant-tape product numbers. The Building Department may ask for the product data sheet to confirm it meets code.

Inspection sequence: the framing/waterproofing inspection happens before drywall closes up. The inspector will look for proper pan slope (1/4 inch per foot toward the drain), membrane continuity (no tears, wrinkles, or exposed seams), and sealant applied at corners and penetrations. If the membrane is not sealed or is wrinkled, the inspector will reject the framing stage, and you'll need to fix it before drywall goes up. A common issue: the contractor installs the membrane but forgets to seal seams with the proper sealant compound (not caulk, not tape—the manufacturer's specified sealing product). This passes the visual inspection but fails in use—water wicks through seams and causes mold within months. Montgomery inspectors increasingly photograph the waterproofing assembly and attach images to the inspection report to create a record.

City of Montgomery Building Department
Montgomery City Hall, Montgomery, Illinois 60538
Phone: (630) 898-8500 (City of Montgomery main line — ask for Building Department) | https://www.montgomeryweb.com (check website for online permit portal link; some permits can be submitted digitally)
Monday–Friday, 8:00 AM–5:00 PM

Common questions

Do I need a permit to replace my toilet with the same model in the same location?

No, toilet replacement in place is exempt from permitting in Montgomery. You can swap the old toilet for a new one without a permit as long as you don't move the rough-in (the distance from the wall to the center of the drain) and don't touch the water supply line or vent. If the supply line or vent need replacement, that triggers a permit. A licensed plumber is recommended but not required by code for a simple swap; make sure your plumber gets the trap seal right and doesn't create an air lock.

My bathroom is vented into the attic right now—can I just leave it there?

No. IRC M1505 and Montgomery code require exhaust ducting to terminate outside the home, not in the attic or soffit. Venting into the attic causes moisture accumulation, mold, and roof rot within 2–3 years. If you're pulling a permit for any bathroom work, the inspector will flag this and require you to extend the duct to an external wall or roof termination. This is non-negotiable and one of the most common code violations. Budget $800–$1,500 to properly duct a bathroom exhaust to the outside.

Can I do the electrical work myself as the owner-builder, or do I have to hire a licensed electrician?

Montgomery allows owner-builder permits for owner-occupied work, which means you can pull the permit and do the labor yourself. However, the electrical design and layout must be code-compliant, and the final inspection must pass. If you're adding a new circuit for a bathroom exhaust fan or light, you need to understand NEC Section 210.8 (GFCI) and Section 215 (AFCI) requirements. Most homeowners find it safer and faster to hire a licensed electrician to design the circuit, run the wire, and handle the inspection. The permit cost is the same regardless; the electrician's labor is the variable. For a simple new 20-amp circuit, budget $600–$1,200 in labor.

What happens if my bathroom drain trap arm is too long?

IRC P2706 limits trap-arm length to 6 feet. If your trap arm exceeds 6 feet, the vent (the 1.5-inch or 2-inch pipe that prevents the trap from siphoning) won't work effectively, and you'll get slow drains, gurgling, or backup. Montgomery inspectors will measure the trap arm during rough-in and reject it if it's over 6 feet. The fix is to either shorten the arm (relocate the fixture closer to the vent stack) or install a new vent stack at the fixture location. This often requires opening walls and adds $2,000–$4,000 in cost. Submit a plumbing schematic with trap-arm length labeled on your permit plan to catch this early.

Do I need a building permit for a simple cosmetic remodel—new vanity, tile, mirror, and paint?

No, if the vanity is a drop-in replacement in the same location (same drain and supply lines), the work is cosmetic and exempt. You can replace the vanity, install new tile, paint, and swap fixtures without a permit. However, if the new vanity location is different from the old one (even 2 feet), or if you're adding a new supply line or drain, a permit is required. When in doubt, call the Montgomery Building Department and describe the work; they'll confirm in 5 minutes.

How long does a bathroom permit take from application to final inspection in Montgomery?

Typically 4–6 weeks: 10–14 days for plan review, 1–2 days to issue the permit after approval, 5–10 days to schedule and complete rough plumbing/electrical/framing inspections, and 3–5 days for the final inspection after all work is done. If there are plan rejections or inspection failures (e.g., waterproofing not sealed, ductwork not sloped), add 1–2 weeks for rework and re-inspection. Coordinating inspections is up to you; call the Building Department to schedule after each phase is complete. Many contractors schedule all three rough inspections on the same day to save time.

Can I move a plumbing vent stack, or does it have to stay in the same location?

Vent stacks can be relocated, but they must remain within the wall or cavity structure, slope upward (or be horizontal with an upward slope at the fixture), and penetrate the roof in the same general location to minimize roof penetrations. If you're relocating a fixture to a new wall, the vent may also need to move. This is complex and almost always requires sealed plumbing plans. The trap-arm distance to the vent is the constraint: if the trap is more than 6 feet away from the existing vent, you need a new vent or a wet-vent secondary drain (which has stricter rules). Most homeowners can't DIY this; hire a plumber and submit their plans with the permit.

Do I need a lead-paint inspection before remodeling a 1970s bathroom?

Illinois law (and federal law) requires lead-paint disclosure for homes built before 1978. If your home was built before 1978, you must assume the paint, drywall, and fixtures contain lead. When you remodel, you must use EPA-certified lead-safe practices: HEPA vacuums, containment, wet-wiping, and proper disposal. A lead inspection or XRF test is not required by Montgomery code for bathroom remodels, but it's recommended to confirm whether lead is present. The EPA pamphlet 'Protect Your Family from Lead in Your Home' is required to be distributed to any buyer; if you're selling soon, a lead-paint remediation report may strengthen your listing. Budget $500–$1,500 for a lead inspection and remediation consulting.

What electrical requirements apply to a new bathroom exhaust fan and light?

Both the exhaust fan and any light fixture in the bathroom must be on circuits protected by GFCI (ground-fault circuit interrupter) at the outlet or by AFCI (arc-fault circuit interrupter) at the breaker. Most often, a new exhaust fan is on a dedicated 20-amp circuit with AFCI protection on the breaker in the panel. A recessed light or mirror fixture over the sink requires GFCI protection (outlet-level or breaker-level). If you're combining the exhaust fan and light on the same circuit, both must have AFCI protection via the breaker. Submit an electrical one-line diagram showing the new breaker, wire gauge (12 AWG for 20 amp), and AFCI type. Montgomery inspectors will verify during rough-electrical inspection that the breaker is correctly labeled and that the wiring is correctly sized and installed in conduit or cable per NEC 300-series rules.

If my bathroom has an operable window, do I still need an exhaust fan?

No, but it depends on the window size. IRC M1505 allows a bathroom to be ventilated by an operable window if the net glass area is at least 5% of the floor area. A 5x8 bathroom is 40 square feet, so 5% = 2 square feet; a window about 2 feet wide and 1 foot tall meets this threshold. However, in practice, most bathrooms also have an exhaust fan because operable windows alone are insufficient in winter, humidity, and moisture peaks. If you're remodeling, the local code official might accept the window-only approach if it meets the 5% threshold, but you'll want to confirm in writing before closing the walls. Adding an exhaust fan is always safer and adds resale value.

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 Montgomery Building Department before starting your project.

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