Which deck ledger flashing details actually survive two decades—membranes, metals, and shingle integration?

Trade Talk
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Which deck ledger flashing details actually survive two decades—membranes, metals, and shingle integration?

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Good copper or quality aluminum flashings put under shingles or siding with a good slope can last for years. Peel-and-stick stuff works well if it’s out of the sun. Keep things clean and check the sealant to make them last even longer.

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Metal flashing with proper shingle overlap lasts longest; membranes fail faster unless fully protected and well-integrated.

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For 20+ year ledger life: metal flashing and self-adhered membrane and proper shingle/siding overlap, with slope and sealed fasteners.

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The longest lasting ledger flashing setups pair a corrosion resistant metal like stainless steel or heavy gauge aluminum with proper shingle style integration behind the siding and over the ledger plus a self sealing membrane over framing before metal install. Key to two decade survival is leaving a drainage gap between ledger and house wall, using kickout ends to shed water, and avoiding direct contact between treated lumber and metal without a barrier

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For longer survival:

Best: Self-adhered membranes (like Trex Seal), copper, stainless steel.

Shingle integration: Use drip cap/Z-flashing above ledger; seal fasteners behind.

Avoid: Aluminum or galvanized on pressure-treated wood.

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For 20-year performance, use corrosion-resistant metal (stainless or coated aluminum/zinc) over a self-adhered membrane, integrated under shingles and siding with end dams. Metal shields the membrane from UV, and proper layering, slope, and drainage ensure long-term protection.