Low (Not Recommended for Novice DIY; significant risk of water damage and code non-compliance if not executed precisely)
Curbless shower construction involves intricate structural modifications, precise floor leveling and sloping, advanced waterproofing techniques, and strict adherence to accessibility standards. These requirements demand experienced professionals to prevent costly water damage and ensure compliance with stringent DuPage County building standards.
Project Guidelines & Rules
General Requirements & Permitting
3 Rules
Obtain necessary building and plumbing permits prior to commencing any work.
Consult with your local municipality or the local building department
All work shall comply with the currently adopted codes: 2024 International Residential Code (IRC), 2023 National Electrical Code (NEC), and the Illinois Plumbing Code.
DuPage County regional standard and adopted codes
Schedule and pass required inspections at various stages, including but not limited to: framing, rough-in plumbing, rough-in electrical, waterproofing, and final inspection.
Local Building Department procedures
Structural Modifications & Subfloor
3 Rules
Floor joists within the shower footprint may require modification (notching, sistering, or dropping) to achieve the necessary floor recess for the shower pan and slope without raising the surrounding bathroom floor. All structural modifications must be engineered and approved.
2024 IRC R502.6, R502.8, R502.11
Subfloor material in the shower area must be appropriate for the waterproofing system and intended finishes, typically concrete board or a reinforced mortar bed designed for wet areas.
2024 IRC R502.2.1, R702.4.2
Ensure adequate structural support for all imposed loads, accounting for increased dead load from tile and live load from wet conditions.
2024 IRC R301.1, R502.1
Drainage & Slope
4 Rules
The shower floor shall be sloped uniformly to the drain. The minimum slope shall be 1/4 inch per foot (2%) and the maximum 1/2 inch per foot (4%). For linear drains at the entrance or wall, ensure adequate drainage away from the entry point.
Illinois Plumbing Code Section 890.1340(b)(1), 2024 IRC P2709.3
The shower drainage system, including the trap, shall be properly sized, vented, and connected to the sanitary drainage system.
Illinois Plumbing Code Section 890.1310, 890.1320, 890.720, 2024 IRC P2709.1
The shower drain opening must be installed flush with the finished floor surface.
DuPage County aesthetic and functional standard for curbless design
Minimum finished shower dimensions (excluding access) must be at least 30 inches by 30 inches, with a total area of no less than 900 square inches.
Illinois Plumbing Code Section 890.1340(a), 2024 IRC R307.2
Waterproofing & Shower Pan
6 Rules
A continuous, watertight, and leak-free shower pan or receptor lining shall be installed beneath the finished floor of the shower area.
Illinois Plumbing Code Section 890.1340(c), 2024 IRC R702.4.3
The pan liner shall extend vertically at least 2 inches above the finished floor level (in lieu of a dam) and extend horizontally to at least the face of the shower walls, forming a continuous watertight enclosure.
Illinois Plumbing Code Section 890.1340(c)(3), 2024 IRC P2709.4
The pan liner must be free from punctures or tears. Sheet materials (e.g., PVC or CPE liners) shall be installed in one piece or with approved solvent-welded joints.
Illinois Plumbing Code Section 890.1340(c)(4), 2024 IRC P2709.4.1
A pre-slope (mortar bed or equivalent) must be provided beneath the waterproofing membrane to direct any water that penetrates the finished tile layer to the weep holes of the drain.
Illinois Plumbing Code Section 890.1340(c)(2), 2024 IRC P2709.4.1 (implied for weep hole drains)
Liquid-applied waterproofing membranes must be compliant with ICC-ES AC115 or other approved standards and installed strictly according to the manufacturer's instructions.
2024 IRC R702.4.3.1
All seams, penetrations (e.g., drain, pipe, fasteners), and transitions within the waterproofing system must be meticulously sealed to ensure a continuous and impenetrable barrier.
DuPage County best practice for moisture control
Wall Construction & Finishes
3 Rules
Wall surfaces within the shower enclosure must be finished with a non-absorbent material (e.g., tile, solid surface) extending to a minimum height of 72 inches above the finished shower floor.
2024 IRC R307.2
Backing material for tile or other finishes in shower areas shall be water-resistant or waterproof cement board or an approved equivalent; gypsum wallboard is prohibited.
2024 IRC R702.4, R702.4.2
A vapor retarder shall be installed behind wall finishes in shower areas to prevent moisture migration into wall cavities.
2024 IRC R702.4.2
Plumbing System
4 Rules
Shower valves shall be pressure-balancing, thermostatic, or combination pressure-balancing/thermostatic types to prevent sudden temperature fluctuations.
Illinois Plumbing Code Section 890.1560(c), 2024 IRC P2708.3
The maximum hot water temperature at the shower head shall not exceed 120°F (49°C) to prevent scalding.
Illinois Plumbing Code Section 890.1560(c) (implied by anti-scald requirements)
All water supply and drainage piping must be installed according to code, including proper sizing, support, and protection against physical damage.
Illinois Plumbing Code Chapters 890.1010-890.1260, 2024 IRC P2601-P2609
The water supply and drainage systems must be tested and inspected for leaks prior to concealment.
Illinois Plumbing Code Section 890.540, 2024 IRC P2503
Electrical System
4 Rules
All 125-volt, single-phase, 15- and 20-ampere receptacles installed within 6 feet (1.8m) of the outside edge of a shower or tub shall have Ground-Fault Circuit-Interrupter (GFCI) protection.
2023 NEC 210.8(A)(1)
No switch or receptacle outlet shall be installed within the shower compartment.
2023 NEC 404.4, 406.9(C)
Lighting fixtures installed within the shower compartment shall be listed for damp or wet locations, as appropriate for their specific placement and exposure to water spray.
2023 NEC 410.10(D)
All wiring methods and materials must comply with the National Electrical Code requirements.
2023 NEC Article 300
Ventilation
2 Rules
Bathrooms containing a shower shall be provided with a mechanical exhaust fan capable of exhausting a minimum of 50 cubic feet per minute (cfm).
2024 IRC M1507.4
Exhaust fans must be vented directly to the outdoors, not into an attic, crawl space, soffit, or other enclosed building cavities.
2024 IRC M1507.2
Accessibility Considerations (Common for Curbless Design)
3 Rules
Where a curbless shower is specifically designed for accessibility, the clear opening width into the shower shall be a minimum of 36 inches.
2024 IRC Chapter 11, ICC A117.1 (referenced standard for accessibility)
Controls and the shower spray unit, if applicable for accessible design, shall be located such that they are usable from a seated position and comply with reach range requirements.
2024 IRC Chapter 11, ICC A117.1
Any grab bars installed must comply with strength, mounting, and placement requirements for accessible design.
2024 IRC R307.2.1 (references A117.1)
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