Home Addition (General)

Administrative & Permitting Requirements 4 Rules

Plan Submission & Approval

IRC R105.1, R106.1 - Plans must be submitted to your local building department, including architectural drawings, structural calculations, site plans, and energy code compliance forms. Professional design is typically required.

Permits Required

IRC R105.2 - A building permit is mandatory. Separate permits for electrical, plumbing, and mechanical work will also be required by your local municipality.

Inspections

IRC R109.1 - Required inspections include, but are not limited to: footing, foundation, framing, rough electrical, rough plumbing, rough mechanical, insulation, drywall, and final inspections. Schedule with your local building department.

Property Line Setbacks

Zoning Ordinances - Compliance with local municipal zoning ordinances regarding setbacks from property lines is mandatory. Verify specific requirements with your local municipality.

Foundations & Structural Elements 5 Rules

Frost Depth

IRC R403.1.4.1 - Footings shall extend a minimum of 42 inches below finished grade or undisturbed ground, whichever is deeper, to protect against frost heave, as per DuPage County regional standards.

Footing Dimensions

IRC R403.1 - Minimum footing width and thickness based on soil bearing capacity and applied loads. Concrete must be minimum 2500 psi. Reinforcement as per structural design.

Foundation Walls

IRC R404.1 - Foundation walls must be designed to resist lateral soil pressure and vertical loads. Minimum 8-inch thickness for concrete or masonry, reinforced as per structural design.

Foundation Drainage

IRC R405.1 - Foundation drainage system required for crawl spaces and basements, consisting of a perforated pipe and gravel or crushed stone. Must discharge to an approved location.

Wood Structural Members (Span/Size)

IRC Chapter 5, 6, 8 - Sizing and spanning of joists, rafters, beams, and headers shall comply with IRC tables or engineered design based on anticipated loads (live and dead loads for DuPage County).

Framing & Enclosure 6 Rules

Wall Framing

IRC Chapter 6 - Wall studs shall be adequately sized and spaced (e.g., 2x4 at 16" o.c. or 2x6 at 24" o.c. for exterior walls), with proper notching and boring limits observed.

Wall Bracing

IRC R602.10 - Exterior walls must be adequately braced against wind and seismic forces as per IRC requirements for DuPage County.

Floor Framing

IRC Chapter 5 - Floor joist sizing and spacing based on span, species, grade, and loading conditions.

Roof Framing

IRC Chapter 8 - Rafter and ceiling joist sizing based on span, pitch, snow load (DuPage County minimum 30 psf ground snow load), and dead loads.

Sheathing (Wall & Roof)

IRC R602.10 (Wall), R803 (Roof) - Minimum sheathing thickness and fastening schedule for wall and roof assemblies.

Windows & Doors

IRC R609, R703.1 - Fenestration shall be properly flashed and sealed to prevent moisture intrusion. Installation per manufacturer's instructions. Energy efficiency requirements (U-factor, SHGC) per IECC.

Roofing 3 Rules

Roof Covering

IRC Chapter 9 - Roof coverings (e.g., asphalt shingles) shall be installed according to manufacturer's instructions and IRC requirements for fastening, underlayment, and flashing. Minimum 2 layers of underlayment required for roof slopes less than 4:12.

Ice Barrier (Ice and Water Shield)

IRC R905.1.2 - An ice barrier is required from the eaves up to a point at least 24 inches inside the exterior wall line of the building, due to DuPage County climate conditions.

Roof Ventilation

IRC R806.1 - Adequate attic ventilation (e.g., 1/150 or 1/300 net free area) is required to prevent moisture buildup and reduce heat gain.

Thermal Envelope & Insulation 5 Rules

Wall Insulation

IRC N1102.1.2, N1102.2.5 (Table N1102.1.2) - Minimum R-value for walls (e.g., R-20 or R-13 + R-5 continuous insulation) as per 2021 IECC (adopted by IRC 2024, energy chapter). Specific to DuPage County climate zone 5.

Ceiling/Attic Insulation

IRC N1102.1.2, N1102.2.1 (Table N1102.1.2) - Minimum R-value for ceilings/attics (e.g., R-49) for DuPage County climate zone 5.

Floor Insulation

IRC N1102.1.2, N1102.2.8 (Table N1102.1.2) - Minimum R-value for floors over unconditioned spaces (e.g., R-30) for DuPage County climate zone 5.

Air Sealing

IRC N1102.4.1 - Mandatory air sealing measures to reduce air leakage in the building envelope, verified by blower door test or visual inspection. Maximum air leakage rate as per code.

Vapor Retarder

IRC R702.7 - Class I or II vapor retarder on the interior side of framed walls, ceilings, and floors in DuPage County's cold climate zone.

Electrical Systems 6 Rules

General Wiring Requirements

2023 NEC 300 - All wiring methods and materials shall comply with NEC 2023. Conductor sizing, overcurrent protection, and grounding/bonding are critical.

GFCI Protection

2023 NEC 210.8 - Ground-fault circuit interrupter (GFCI) protection required for all 120-volt, single-phase, 15- and 20-ampere receptacles installed in bathrooms, garages, outdoors, crawl spaces, basements, kitchens, and other damp/wet locations.

AFCI Protection

2023 NEC 210.12 - Arc-fault circuit interrupter (AFCI) protection required for all 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices installed in dwelling unit kitchens, family rooms, dining rooms, living rooms, parlors, libraries, dens, bedrooms, sunrooms, recreation rooms, closets, hallways, laundry areas, or similar rooms or areas.

Smoke & Carbon Monoxide Alarms

IRC R314, R315; 2023 NEC 760 - Hardwired, interconnected smoke alarms with battery backup on every level, in each sleeping room, and outside each sleeping area. Carbon monoxide alarms are also required in sleeping rooms and on each level with a fuel-burning appliance or attached garage.

Service Entrance & Load Calculations

2023 NEC 220, 230 - Electrical service (e.g., 200 amp minimum for new additions) must be adequately sized for the total calculated load. Load calculations must be submitted.

Receptacle & Lighting Outlets

2023 NEC 210.52 - Receptacles must be installed so that no point along a wall line is more than 6 feet from a receptacle. Lighting outlets required in habitable rooms, bathrooms, hallways, and stairs.

Plumbing Systems 7 Rules

General Requirements

Illinois Plumbing Code (as adopted, based on 2021 IPC) - All plumbing systems and components must comply with the Illinois Plumbing Code. This includes water supply, drainage, waste, and vent systems.

Water Service & Sizing

Illinois Plumbing Code 604 - Water service pipe and distribution piping shall be sized to provide adequate pressure and flow for all fixtures in the addition.

Drain, Waste, and Vent (DWV) Sizing

Illinois Plumbing Code 701, 904 - DWV piping shall be sized based on fixture units and slope. Proper venting is critical to prevent trap siphonage and backpressure.

Fixture Connections

Illinois Plumbing Code 405 - All plumbing fixtures must be provided with an approved trap. Hot and cold water supplies must be accessible.

Water Heater

Illinois Plumbing Code 502, 504 - Water heaters shall be installed according to manufacturer's instructions and code requirements, including TPR valve discharge, combustion air, and venting (if fuel-fired).

Backflow Prevention

Illinois Plumbing Code 603 - Required on specific connections to prevent contamination of the potable water supply.

Sewer Connection

Illinois Plumbing Code 701 - Connection to the public sewer system or an approved private sewage disposal system (septic) as permitted by local health department and your local municipality.

Mechanical Systems (HVAC) 5 Rules

Heating & Cooling Loads

IRC M1401.3 - HVAC systems shall be designed and sized based on ACCA Manual J (heating and cooling load calculations) and Manual S (equipment sizing and selection) for the addition.

Duct Systems

IRC M1601 - Ductwork shall be properly sized, sealed, and insulated (e.g., R-8 in unconditioned spaces) to minimize heat loss/gain and ensure proper airflow.

Exhaust Fans

IRC M1507 - Exhaust fans required in bathrooms (50 cfm intermittent or 20 cfm continuous) and kitchens (vented range hood or whole-house ventilation as per code) to remove moisture and odors.

Combustion Air

IRC M1703 - Adequate combustion air supply for fuel-burning appliances (furnaces, water heaters) must be provided, preventing backdrafting.

Appliance Venting

IRC M1801, M1804 - Fuel-fired appliances must be properly vented to the outdoors, complying with clearance requirements and material specifications.

Fire Safety & Egress 2 Rules

Egress Windows

IRC R310 - Every sleeping room and basement must have at least one openable emergency escape and rescue opening. Minimum clear opening dimensions: 20" width, 24" height, 5.7 sq ft area (5.0 sq ft at grade), sill height not more than 44" above floor.

Fire Separation (Attached Garages)

IRC R302.5 - Walls and ceilings separating a dwelling from an attached garage must have specific fire-resistance ratings (e.g., 1/2-inch gypsum board on garage side).

Site Work & Drainage 2 Rules

Grading

IRC R401.3 - Finish grade must slope away from the foundation a minimum of 6 inches in the first 10 feet. Swales or other means of positive drainage may be required.

Erosion Control

Local Regulations - Implement temporary erosion and sediment control measures during construction to prevent runoff and soil loss, as required by your local municipality.