Old roofs frequently have neither. Without intake at the eave and exhaust at the ridge, the attic cooks the shingles from underneath and cuts their life. Adding ventilation during a reroof costs little; retrofitting later costs a great deal more.

This is most common in homes built before about 1940. Pre-war construction — galvanized supply, cast iron drains, cloth-wrapped wiring, ungrounded circuits.

Related

• Two or three layers of shingle already on the roof
• Plank decking with gaps between the boards
• Rust streaks below the chimney flashing
• Wood shingle under the asphalt
• Valley metal rusted or missing
• Masonry chimney needs work
• Sagging visible along the ridge line
• Roof over an addition with a different pitch

Back to Roofing.

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Written by Jaylan Jones. I Like To Exterior Services earns a referral fee when a call connects to a contractor. See our business-model disclosure.