What happens if you skip the permit (and you needed one)
- Stop-work order and $250–$500 fine if the city inspector or a neighbor reports unpermitted work; you'll then pay double the permit fee ($200–$400) to legalize it.
- Insurance claim denial if a water leak or defect occurs post-replacement and the insurer discovers unpermitted work — common in Danville's older neighborhoods where home insurance is already tight.
- Historic-district violation fine of $100–$300 per day if you replaced a window in the overlay without design-review approval, plus forced removal and reinstallation of original-profile windows.
- Title disclosure requirement: when you sell, Illinois Residential Real Property Disclosure Act mandates you disclose unpermitted work, which kills buyer confidence and can reduce home value by 5–10% in Danville's market.
Danville window replacement permits — the key details
Illinois Residential Building Code Section 101.2 and Danville Municipal Code Chapter 12 (Building and Construction) adopt the 2021 IBC as amended. The core exemption is straightforward: replacement of an existing window with a new window of the same opening size, using the same frame type (single-hung to single-hung, casement to casement), with no change to sill height or egress compliance, requires no permit. This is codified in IRC R612 (Window Fall Prevention) and IRC R310 (Egress from Bedrooms and Basements) — if your replacement doesn't alter egress sill height or fall-protection compliance, you're exempt. The logic is that the original opening was already code-compliant when it was built, so swapping out the sash doesn't trigger a review. However, Danville's local amendment adds one wrinkle: energy code. IECC 2021 (which Illinois adopted statewide) requires replacement windows to meet U-factor limits based on climate zone. Danville straddles zones 4A and 5A, so northern Danville (near Gilman) uses U-0.32, southern Danville (toward Covington) uses U-0.30. Your new window must meet that spec, but again, no permit is needed — the burden is on you to buy compliant windows. If you don't, and the city inspector notices during a later unrelated permit, you'll be asked to replace them.
Contact city hall, Danville, IL
Phone: Search 'Danville IL building permit phone' to confirm
Typical: Mon-Fri 8 AM - 5 PM (verify locally)