What are the signs of blocked soffit vents?
By Best Roofing Answers · Published May 2026 · Updated July 2026
Blocked soffit vents commonly show up as summer attic temperatures above 130°F, winter ice damming at the eaves, mold or frost on the underside of the roof deck, and premature curling of shingles above the affected soffit — any one of these signals a ventilation deficit under IRC R806 code minimums.
Why soffit vents get blocked
Per DOE and IECC guidance, the most common cause is blown-in attic insulation covering the vent openings without baffles. Retrofit polystyrene baffles between rafters preserve airflow at each vent — a low-cost fix that restores the 1:150 (or 1:300 with balanced ridge exhaust) net free vent area required by code.
Painted-over soffit panel perforations are another common failure — the paint film seals the tiny holes and the vent becomes decorative only. A visual check from below is enough to spot this.
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