Original galvanized step and counter flashing corrodes through well before the masonry fails. Chimney flashing is the most common leak point on old roofs and the one most often reused during a reroof because replacing it means cutting into mortar.

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
• Wood shingle under the asphalt
• No ridge vent and no soffit intake
• 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.