Walk this checklist yourself — flashlight in hand, in your own attic.
Why ventilation matters
Inadequate attic ventilation is the single biggest cause of ice dams, premature shingle failure, and summertime cooling-bill spikes in Evanston. The fix is rarely expensive. The diagnosis just requires 30 minutes and a flashlight.
The walk-through
1. Find the intake. Step outside and look up at your soffits. Do you see continuous perforated vent material, or just solid boards with maybe a couple of small box vents? Solid soffits = no intake. That alone is an ice-dam risk.
2. Find the exhaust. Look at the roof ridge. Is there a continuous ridge vent (a slightly raised cap running the length of the ridge)? Or just a few square box vents (called "turtle vents") scattered around? Box vents alone are usually inadequate.
3. Open the attic hatch. Look up. Can you see daylight at the eaves through the soffit baffles? If so, intake is reaching the attic. If insulation is jammed up against the underside of the deck at the eaves, the soffits are blocked.
4. Look at the ridge. Can you see daylight at the peak through the ridge vent? Good — exhaust is working.
5. Check the insulation depth. Use a ruler. Most pre-1980 Evanston attics have 6–10 inches. Modern code is 16–20 inches (R-49 to R-60).
6. Look for staining. Dark patches on the underside of the deck or on the rafters indicate condensation problems — which mean ventilation is inadequate.
What the fix looks like
For most Evanston homes, the fix is: cut continuous soffit venting, install ridge vent, install soffit baffles to keep insulation off the underside of the deck, air-seal the ceiling plane (recessed lights, attic hatch, plumbing chases), and blow in cellulose to R-60.
Total cost: $4,800 to $7,500. Total time: one to two days. Eligible for the IRA 25C tax credit. Pays for itself in 5–9 years through energy savings, even before you count the avoided cost of ice-dam repairs and premature roof replacement.