A Homeowner Guide With Verified Sources

Downers Grove is known for having a structured and reliable permitting and inspection process. However, many homeowners are surprised by how early and how often the Village requires permits, inspections, and compliance checks.

This guide summarizes what is verifiable through public sources, what falls under DuPage County’s adopted building codes, and what is considered industry-standard best practice.

1. Who Controls the Codes in Downers Grove

Downers Grove uses a combination of:

  1. Village of Downers Grove Permit Requirements

    The village requires permits for roofs, siding, decks, structural work, window size changes, electrical work, plumbing, and more (Village of Downers Grove, n.d.-a).


  2. DuPage County Building & Zoning Adopted Codes

    DuPage County enforces model codes including International Building Code (IBC) and related standards, which apply to structural and safety elements (DuPage County Building & Zoning, 2023).


  3. Illinois State Requirements (for certain trades)

    Roofing contractors must be licensed at the state level (Illinois Roofing Industry Licensing Act, 2024).

Takeaway: All structural and most exterior work in Downers Grove must follow a combination of Village permitting rules + DuPage County model code requirements.

2. Roofing Requirements in Downers Grove

Permit Requirement

A permit is required for roof replacement in Downers Grove (Village of Downers Grove, n.d.-a).

Structural Code Oversight

Roof structural elements fall under DuPage County’s adopted IBC standards, which regulate framing, decking, load, and attachment (DuPage County Building & Zoning, 2023).

Architectural/Engineering Requirements

If framing or structural decking is altered, stamped drawings may be required (DuPage County Building & Zoning, 2023).

Industry Best-Practice (Not explicitly codified)

Not code-mandated but strongly recommended:

• Full tear-off

• Synthetic underlayment

• Ice and water membrane

• Updated flashing

• Intake and exhaust ventilation

These are standards recommended by roofing industry bodies, local professionals, and building-science guidelines.

3. Siding Requirements

Permit Requirement

Siding replacement requires a Village permit (Village of Downers Grove, n.d.-a).

Water-Resistive Barrier Requirement

The International Building Code requires a water-resistive barrier behind exterior cladding to protect sheathing from water intrusion (International Building Code, as cited in Barricade Building Products, 2020).

Since Downers Grove relies on IBC for structural requirements, WRB compliance applies.

Flashing Requirements

IBC requires window and door flashing to manage moisture (International Building Code, as cited in Barricade Building Products, 2020).

Historic / Neighborhood Rules

Downers Grove has designated historic districts, and some homes may require additional approvals. These are handled case-by-case via zoning (Village of Downers Grove, n.d.-b).


Note: No single public document lists universal material or color restrictions; these vary by property and district.

4. Soffit, Fascia, and Attic Ventilation

Downers Grove follows model building code ventilation requirements through DuPage County adoption.

Ventilation Requirement

Model code requires attics to have adequate ventilation to reduce moisture and heat (DuPage County Building & Zoning, 2023).

Soffit Ventilation

Air intake through soffit vents is part of the ventilation ratio requirements in the model code.


Note: The exact ratio is based on attic square footage and follows the IBC/IRC general requirements adopted by DuPage County.


Industry Best-Practice Recommendation

Baffles to prevent insulation from blocking soffit vents are industry standard but not separately listed in public village code sources.

5. Gutter and Downspout Requirements

While Downers Grove does not publish a village-specific gutter code:

Drainage Requirements

Model code adopted by DuPage County requires drainage systems to direct water away from the structure (DuPage County Building & Zoning, 2023).

Downspout Extensions

IBC drainage requirements prohibit directing water toward neighboring properties.

6. Deck Requirements

Decks in Downers Grove follow DuPage County requirements + general Illinois deck standards.

Permit Requirement

Village permit required (Village of Downers Grove, n.d.-a).

Frost Line Footings

Deck footings must reach below frost depth for safety. Frost depth in DuPage County is consistently 42 inches (City of Wheaton, 2024).

Structural Standards

Illinois deck-building codes require:

• Guardrails for decks over 30 inches

• Ledger boards attached with approved fasteners

• Joist hangers at connections

• Proper stair rise/run

(Hard Decks, n.d.)


These are widely accepted as standard Illinois deck code requirements and match building-department interpretations across DuPage County municipalities.

7. Basement Finishing Requirements

Basements follow DuPage County building code rules.

Egress Requirements

Basements with bedrooms must have compliant egress with minimum clear openings and access (DuPage County, 2023).

Electrical Requirements

Electrical work must meet adopted electrical code standards.

Plumbing & Mechanical

Plumbing and HVAC modifications must comply with adopted model code and require separate permits (DuPage County, 2023).

Industry Best-Practice Recommendations

Moisture management (vapor barrier, drainage, insulation) is a building-science recommendation but not a Downers Grove-specific code mandate.

8. Why Using a Local Licensed Contractor Matters

State Requirement

Roofing work in Illinois requires a state license (Illinois Roofing Industry Licensing Act, 2024).

Permit Filing

The Village allows only homeowners or licensed contractors to pull required permits (Village of Downers Grove, n.d.-a).

Structural Work

Structural plans often require engineer/architect review under DuPage County’s adopted building code (DuPage County, 2023).


References

Barricade Building Products. (2020). House wrap code requirements: Understanding the IRC & IBC. https://barricadebp.com/news/house-wrap-code-requirements

City of Wheaton. (2024). 2024 International Residential Code amendments. https://www.wheaton.il.us/1203/2024-International-Residential-Code-Amen

DuPage County Building & Zoning. (2023). Building code (clean version). https://cms5.revize.com/revize/dupage/Document_Center/Department/Building%20and%20Zoning/Building%20and%20permit/Building%20Code/Building%20Code%20Clean%20Version%2011-14-2023.pdf

Hard Decks. (n.d.). Illinois deck building codes: What homeowners should know. https://www.harddecks.com/deck-building-codes

Illinois Compiled Statutes. (2024). Roofing Industry Licensing Act. https://www.ilga.gov/legislation/ilcs/ilcs3.asp?ActID=13 

Village of Downers Grove. (n.d.-a). Permits and applications. https://www.downers.us/permit

Village of Downers Grove. (n.d.-b). Historic preservation. https://www.downers.us/govt/departments/community-development/historic-preservation