Not recommended for DIY. This project requires professional architectural and structural engineering, licensed trades (electrical, plumbing, HVAC), and specialized construction expertise to ensure safety, code compliance, and structural integrity.
Second story additions involve significant structural modifications, integration of multiple building systems (electrical, plumbing, HVAC), and adherence to comprehensive code requirements, including local climate-specific standards for DuPage County.
Project Guidelines & Rules
General & Administrative Requirements
3 Rules
Obtain all necessary permits from your local building department prior to any construction.
IRC R105.1
Submit complete architectural and structural plans prepared by Illinois-licensed design professionals.
IRC R106.1
Ensure all required inspections (e.g., foundation, framing, rough-in electrical, plumbing, insulation, final) are scheduled and approved by the local building department.
IRC R109.1
Structural Requirements
8 Rules
Foundations for new or extended bearing walls must extend to a minimum frost depth of 42 inches below finished grade, characteristic of DuPage County climate.
IRC R403.1.4.1
Footings shall be sized to support the increased dead and live loads of the second story, designed by a licensed structural engineer.
IRC R403.1
Existing foundation and framing members must be evaluated by a structural engineer to ensure adequate capacity for the increased loads. Reinforcement or new bearing points may be required.
IRC R301.1, R502.1
Floor framing for the second story must be adequately sized for residential live loads (minimum 30 psf for habitable space) and dead loads.
IRC R301.1.1, R301.5, R502.2
Wall framing must comply with IRC requirements for bearing and non-bearing walls, with appropriate stud sizing and spacing based on load and height.
IRC R602
Roof framing must be designed for DuPage County's climate, including minimum 25 psf ground snow load and 115 mph 3-second gust wind speed.
IRC R301.2.1, R301.2.2
Lateral load resistance (wind and seismic, typically Seismic Design Category B for DuPage County) must be addressed through adequate bracing, shear walls, or other engineered systems for the entire structure.
IRC R602.10, R602.10.1
Anchor bolts, straps, and connectors must be specified and installed as per structural design to resist uplift and lateral forces.
IRC R403.1.6, R602.10
Building Envelope & Energy Efficiency
4 Rules
Exterior walls and roof assemblies must meet minimum insulation R-values specific to DuPage County (Climate Zone 5).
IRC N1102.1 (Based on IECC 2021 adoption)
Windows and doors must meet U-factor and SHGC requirements for Climate Zone 5.
IRC N1102.5 (Based on IECC 2021 adoption)
Air sealing measures are required to minimize uncontrolled air leakage.
IRC N1102.4
Roofing materials and installation must comply with IRC R905, including appropriate underlayment and ventilation.
IRC R905, R806
Electrical Systems
6 Rules
All electrical wiring, devices, and installations must comply with the 2023 National Electrical Code.
2023 NEC
Arc-Fault Circuit Interrupter (AFCI) protection is required for all 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets or devices in all habitable rooms of the dwelling unit.
NEC 210.12(A)
Ground-Fault Circuit Interrupter (GFCI) protection is required for all 120-volt, single-phase, 15- and 20-ampere receptacles installed in bathrooms, garages, outdoors, and other specific locations.
NEC 210.8(A)
A minimum of one 20-ampere branch circuit is required for bathroom receptacles.
NEC 220.14(J)
Adequate receptacles, lighting, and switch control must be provided in all new areas.
NEC 210.52, 210.70
The existing electrical service must be evaluated by a licensed electrician to ensure it can safely handle the increased load of the second story addition. Service upgrade may be required.
NEC 220.82
Plumbing Systems
6 Rules
All new plumbing installations, alterations, and repairs must comply with the Illinois Plumbing Code.
Illinois Plumbing Code (77 Ill. Adm. Code 890)
New water supply lines must be adequately sized to serve all new fixtures, maintaining proper pressure and flow.
IL Plumbing Code Part 890, Subpart D
Drainage, Waste, and Vent (DWV) systems must be correctly sized and sloped, with proper venting to prevent trap siphonage and backpressure.
IL Plumbing Code Part 890, Subpart G & H
Backflow prevention devices are required where potential cross-connection hazards exist.
IL Plumbing Code Part 890, Subpart J
Ensure access to cleanouts is maintained for new DWV lines.
IL Plumbing Code Part 890, Subpart I
Hot water distribution must include thermal expansion protection where required.
IL Plumbing Code Part 890, Subpart D
Mechanical Systems & Ventilation
4 Rules
HVAC system sizing must be re-evaluated to accommodate the added conditioned space and ensure proper heating and cooling capacity for the entire dwelling.
IRC M1401.3
Ductwork for the new areas must be sealed and insulated in unconditioned spaces.
IRC M1601.4, N1103.2
Exhaust ventilation is required in bathrooms (minimum 50 cfm intermittent or 20 cfm continuous) and kitchens.
IRC M1505.4, M1507.3
Combustion air and venting for fuel-burning appliances must be maintained or modified as required.
IRC M1701
Fire Safety & Egress
4 Rules
Smoke alarms are required on every level of the dwelling, including the new second story, and in each sleeping room. Alarms must be interconnected.
IRC R314.3
Carbon Monoxide (CO) alarms are required outside each separate sleeping area in the immediate vicinity of the sleeping rooms.
IRC R315.3
Emergency escape and rescue openings (egress windows) are required in all new sleeping rooms on the second story.
IRC R310.1
Stairways providing access to the second story must meet dimensional requirements for rise, run, headroom, and handrails.
IRC R311.7
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