Not Recommended. Due to the comprehensive nature of the project involving structural modifications, new utility services (electrical, plumbing, HVAC), and life safety requirements, professional design and licensed contractors are strongly advised to ensure compliance with all applicable codes and local ordinances.
This project type often involves significant alterations to an existing structure or a new addition, requiring coordination across multiple trades including structural, electrical, plumbing, and HVAC. Navigating local zoning regulations, comprehensive plan review, and multiple inspections from your local building department adds to the complexity. The integration of a complete living unit demands adherence to full residential code requirements, distinct from minor renovations.
Project Guidelines & Rules
General Project Requirements
4 Rules
Obtaining all necessary building permits from your local municipality prior to commencing any work.
2024 IRC R105.1; Local Building Department Requirements
Compliance with local zoning ordinances for accessory dwelling units or multi-generational living spaces, including setbacks, lot coverage, and occupancy limits.
Local Zoning Ordinance; DuPage County Land Use and Zoning Ordinance (where applicable for unincorporated areas)
Submission of professionally prepared architectural and engineering plans for structural, electrical, and plumbing systems.
2024 IRC R106.1; 2023 NEC 80.29; Illinois Plumbing Code 890.110
Adherence to DuPage County storm water management requirements for any new impervious surfaces or grading changes.
DuPage County Stormwater Management Ordinance
Structural Elements
4 Rules
Foundation depth to extend a minimum of 42 inches below finished grade to meet DuPage County's frost depth requirements.
2024 IRC R403.1.4.1 (Illinois State Amendment); DuPage County Regional Standard
Footing and foundation design to accommodate anticipated soil bearing capacity and all imposed live and dead loads.
2024 IRC R401.1, R403.1; DuPage County Soil Conditions
Framing modifications, including floor joists, headers, and bearing walls, must be engineered to support new loads.
2024 IRC Chapters 5 & 6
Structural integrity of the existing building must be maintained and reinforced as necessary for new loads and alterations.
2024 IRC R102.7
Electrical Systems
6 Rules
All new electrical wiring and installations must comply with the latest adopted edition of the National Electrical Code.
2023 NEC (NFPA 70)
Adequate electrical service capacity for the new suite, potentially requiring an upgrade to the existing main service.
2023 NEC 220.82, 230.79
Required 20-ampere small appliance branch circuits for kitchen and dining areas (minimum two).
2023 NEC 210.52(B)
Ground-Fault Circuit-Interrupter (GFCI) protection required for all receptacles in bathrooms, kitchens, unfinished basements, garages, and outdoors.
2023 NEC 210.8(A)
Arc-Fault Circuit-Interrupter (AFCI) protection required for all 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices in dwelling units, unless specifically exempted.
2023 NEC 210.12(A)
Interconnected smoke alarms required in each sleeping room, outside each separate sleeping area, and on every level. Carbon Monoxide alarms required where fuel-burning appliances are present or an attached garage exists.
2024 IRC R314.3, R315.3
Plumbing Systems
5 Rules
All plumbing installations must comply with the current adopted edition of the Illinois Plumbing Code.
Illinois Plumbing Code (77 Ill. Adm. Code 890)
Proper sizing of water supply and distribution pipes for all fixtures to ensure adequate flow and pressure.
Illinois Plumbing Code 890.340
Waste and vent piping systems designed and installed to ensure adequate drainage and prevent siphonage of fixture traps.
Illinois Plumbing Code Chapter 9 (890.900 et seq.)
Backflow prevention devices required for certain connections, such as irrigation systems or where potential for contamination exists.
Illinois Plumbing Code 890.1130
Water heater sizing appropriate for the additional demand of the multi-generational suite.
Illinois Plumbing Code 890.310; 2024 IRC M1305.1.2
Heating, Ventilation, and Air Conditioning (HVAC)
5 Rules
Heating and cooling system sized to maintain comfortable indoor temperatures, based on calculated heating and cooling loads for the new space.
2024 IRC M1401.3; ACCA Manual J (load calculations)
Mechanical exhaust ventilation required in bathrooms with a minimum airflow rate.
2024 IRC M1505.4
Kitchen range hoods or other local exhaust systems for cooking appliances, vented to the outside.
2024 IRC M1503.1
Adequate combustion air supply for fuel-burning appliances, where applicable.
2024 IRC M1701.1
All HVAC ductwork must be sealed and insulated according to energy code requirements.
2024 IRC N1103.2, N1103.3
Egress and Life Safety
4 Rules
Emergency escape and rescue openings (windows or doors) required in all sleeping rooms and basements with habitable space.
2024 IRC R310.1
Minimum ceiling height of 7 feet for habitable spaces, hallways, bathrooms, toilet rooms, and laundry rooms.
2024 IRC R305.1
Handrails required for stairs with four or more risers; guardrails required for open-sided walking surfaces, stairs, and ramps more than 30 inches above the floor or grade below.
2024 IRC R311.7, R312.1
Fire separation may be required between dwelling units if the multi-generational suite is classified as a separate dwelling unit.
2024 IRC R302.3 (where applicable for separate dwelling units)
Energy Efficiency
3 Rules
Insulation R-values for walls, ceilings, and floors must meet DuPage County's climate zone requirements (Climate Zone 5).
2024 IRC Chapter 11 (based on 2021 IECC)
Windows and doors installed must have U-factors and Solar Heat Gain Coefficients (SHGC) compliant with the energy code.
2024 IRC N1102.3
Air sealing of the building envelope to minimize uncontrolled air leakage, including insulation and fenestration installation.
2024 IRC N1102.4
