Not recommended for typical DIYers. This project requires expertise in multiple trades, adherence to complex building codes (structural, electrical, plumbing, energy), and proper permitting and inspection processes. Licensed professionals are strongly advised for all critical path items.
This project typically involves significant modifications across multiple disciplines including structural, plumbing, electrical, and HVAC. It often requires foundation work, new framing, extensive utility extensions, and coordination of various trades, making it challenging for homeowners without extensive construction experience and requiring adherence to DuPage County building standards.
Project Guidelines & Rules
Permitting & Planning
3 Rules
Plan Submission & Approval
All construction plans must be submitted to and approved by your local municipality's building department. Plans must clearly delineate existing and proposed conditions. IRC R105.1, R106.1
Permit Acquisition
Prior to commencement of any work, all necessary building, electrical, plumbing, and HVAC permits must be obtained from the local building department. IRC R105.1
Site Plan Requirements
A detailed site plan showing property lines, existing structures, proposed additions with dimensions, setbacks, and utility locations is often required. Your local municipality may have specific additional requirements.
Structural & Foundation
5 Rules
Frost Depth for Foundations
All exterior footings shall extend to a minimum depth of 42 inches below grade (measured from the finished grade to the bottom of the footing) to mitigate frost heave, or per a geotechnical report, whichever is greater, for DuPage County's climate. IRC R403.1.2
Foundation Drainage
Footing drains or other approved means shall be provided at the base of the foundation walls and shall discharge to an approved location. IRC R405.1
Floor Live Load
Habitable room floors shall be designed for a minimum uniform live load of 40 pounds per square foot (psf). IRC Table R301.5
Roof Live Load/Snow Load
Roofs shall be designed to withstand a minimum ground snow load of 30 psf for DuPage County, adjusted for roof slope and geometry. IRC R301.2
Structural Member Sizing
All beams, joists, rafters, and headers must be engineered or sized per IRC span tables based on design loads, ensuring structural integrity for the proposed addition. IRC R502, R602, R802
Exterior Envelope
4 Rules
Weather-Resistive Barrier
All exterior walls shall be provided with a continuous weather-resistive barrier behind the exterior wall covering, properly lapped and flashed. IRC R703.1
Wall Bracing
The new wall sections must comply with IRC R602.10 wall bracing requirements based on seismic and wind design categories applicable to DuPage County.
Roofing Materials & Installation
Roofing materials must be approved for the local climate, installed per manufacturer's instructions, and conform to IRC Chapter 9 requirements.
Fenestration (Windows/Doors)
All windows and doors must be installed with proper flashing and sealing. Energy efficiency U-factor and Solar Heat Gain Coefficient (SHGC) requirements per IRC Chapter 11 (2024 IRC for Zone 5).
Interior Layout & Finishes
3 Rules
Ceiling Height
Habitable rooms shall have a minimum ceiling height of 7 feet. Bathrooms, hallways, and utility rooms shall have a minimum height of 6 feet 8 inches. IRC R305.1
Room Size
At least one habitable room in the dwelling unit shall have not less than 120 square feet of floor area. Other habitable rooms (except kitchens) shall have not less than 70 square feet of floor area. IRC R304.1, R304.2
Glazing Requirements
Safety glazing is required in hazardous locations such as glass in and around bathtubs, showers, and certain door panels. IRC R308
Plumbing Systems
5 Rules
Water Service & Distribution
Sizing and installation of water supply piping shall conform to Illinois Plumbing Code (IPC) Sections 603, 604, and 605, ensuring adequate pressure and flow.
Drain, Waste, and Vent (DWV) Systems
All new drainage, waste, and vent piping must comply with IPC Sections 704, 901, and 1002, including proper sizing, slope, venting, and trap requirements.
Water Heater Installation
Water heater installations must include proper temperature and pressure relief valves with discharge piping. Seismic strapping may be required. IPC Sections 504, 505
Fixture Requirements
All plumbing fixtures must meet minimum efficiency standards (e.g., 2.5 gpm for showerheads, 1.5 gpm for lavatories, 1.28 gpf for water closets). IPC Sections 402, 407
Backflow Prevention
Appropriate backflow prevention devices are required for certain connections, particularly irrigation systems or outdoor hose bibbs, to protect the potable water supply. IPC 603.2
Electrical Systems
6 Rules
Service & Feeder Sizing
Electrical service and feeder sizing shall be calculated per NEC Article 220 to ensure adequate capacity for the expanded load.
Receptacle Outlets
General-purpose receptacle outlets must be spaced so that no point along the wall line in any habitable room is more than 6 feet from an outlet. GFCI protection is required for all bathroom, kitchen countertop, garage, and outdoor receptacles. NEC 210.52, 210.8
Lighting Outlets
At least one switch-controlled lighting outlet shall be installed in every habitable room, hallway, stairway, attached garage, and at exterior doors. NEC 210.70
Arc-Fault Circuit-Interrupter (AFCI) Protection
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 shall be protected by a listed AFCI. NEC 210.12(A)
Smoke & Carbon Monoxide Alarms
Interconnected smoke alarms with battery backup are required in each sleeping room, outside each separate sleeping area in the immediate vicinity of the bedrooms, and on every level of the dwelling. Carbon monoxide alarms are required on every level with sleeping areas. NEC 760 (for power source), IRC R314, R315
Wiring Methods
All wiring must be installed per NEC Chapter 3, including proper cable/conduit fill, support, and protection against physical damage.
HVAC & Energy Efficiency
4 Rules
Heating & Cooling System
The HVAC system must be adequately sized for the new area, and all ducts sealed to prevent leakage. Installation must comply with manufacturer's instructions and IRC M1401, M1601.4.
Ventilation
Bathrooms shall be provided with a mechanical exhaust fan capable of exhausting 50 cubic feet per minute (CFM) intermittently or 20 CFM continuously, ducted to the exterior. IRC M1505.4
Insulation Requirements (DuPage County Climate Zone 5)
Minimum insulation R-values: Ceilings R-49, Wood-frame walls R-21, Floors R-30 (where applicable). IRC Chapter 11, Table N1102.1.3
Air Sealing
The building envelope must be sealed to limit air leakage, including penetrations for plumbing, electrical, and mechanical systems. IRC N1102.4.1
Safety & Egress
2 Rules
Emergency Escape & Rescue Openings
Every sleeping room shall have at least one openable emergency escape and rescue opening (window or door). Minimum clear opening dimensions: 20 inches wide, 24 inches high, 5.7 square feet area. Sill height no more than 44 inches above the floor. IRC R310
Stairways & Handrails
Any new or modified stairways must comply with IRC R311.7, including rise and run dimensions, headroom, and handrail/guardrail requirements (34-38 inches for handrails, 36-42 inches for guardrails in open areas). Guardrails required on open sides of stairs and landings 30 inches or more above grade. IRC R312
