Chicago Roofing Code: Maximum Two Layers (With Exceptions)

The Chicago Building Code permits a maximum of two layers of roofing on any roof surface.

The Rule

• Standard roofs (sloped): Max 2 layers total
• Low-slope/flat roofs: Different rules — often complete tear-off required for membrane systems (TPO, EPDM, modified bitumen)

Key Code References

• Chicago Municipal Code 14B-15-1507 (based on IBC 2018 with Chicago amendments)
• 14B-15-1511 — Reroofing requirements
• 14B-15-1512 — Roof replacement vs. recover

Permit Requirements

• Permit required for all reroofing/recovery work
• Licensed roofing contractor must pull permit
• Inspections: Deck inspection (after tear-off), final inspection
• Ice barrier: Required (2 ft inside wall line) — Chicago climate zone 5

Practical Advice

1. Always verify existing layer count — hidden layers common
2. Tear-off preferred — inspect deck, install proper underlayment, flashing
3. Weight: 2 layers asphalt = ~4-5 psf added; check structural capacity
4. Warranty: Manufacturers often void if installed over existing roof
5. Energy code: IECC 2018/2021 — may require insulation upgrade on reroof

Chicago Dept of Buildings (DOB) enforces strictly. Hire a licensed Chicago roofer who pulls permits. Unpermitted work = stop-work orders, fines, sale complications.