Valleys carry more water than any other part of the roof. On an old roof the metal underneath is often gone entirely and the shingles are woven across bare deck.

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
• No ridge vent and no soffit intake
• 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.