Salt Air and Your Roof: Choosing Materials on Long Island

Salt air is not a single condition on Long Island. A house on the beach is not in the same environment as a house well inland. That gradient changes the right material at every layer of a roof, from the gutters and flashing up through the roof covering. This guide is a general framework, and a site visit gives a better answer for a specific house.

The exposure gradient

Exposure generally falls as you move away from open water. Waterfront and beach properties take direct salt spray. Communities near the Atlantic and the south-shore bays have sustained salt air without the spray load. Properties well inland see much less. The South Shore generally has more exposure to the ocean than the North Shore, though neither is immune.

Ask where your house sits relative to the water and the prevailing wind, and choose materials for that exposure, not for a national default.

Aluminum gutters and leaders

Aluminum is the standard gutter material on Long Island and it performs adequately in most applications. In salt air the failure mode is surface oxidation progressing to perforation, and you usually see white chalking and pitting before the gutter fails, which gives you time to act.

Closer to the water, heavier-gauge aluminum buys more time before salt oxidation wears through the gutter bottom, where standing water speeds the process up. At the water's edge, copper is worth serious consideration.

Copper gutters and leaders

Copper behaves differently from aluminum in salt air. Aluminum oxidizes and weakens. Copper oxidizes and forms a patina, a stable surface layer that protects the metal underneath. The green patina on older copper is the protection working, not a sign of failure.

In coastal conditions, copper tends to perform well over time. The cost is higher than aluminum, but on a house you plan to keep, copper at the coast can be the economical choice over the life of the building. All copper work is soldered.

Asphalt shingles

Standard architectural shingles carry a manufacturer's rating for normal conditions. In coastal salt air and strong sun, which open lots and waterfront properties get plenty of, real-world service life can be shorter than the rating. Granule loss speeds up, and the granules are what protect the shingle mat from sunlight.

Some shingles are available with algae-resistant granules. That is a reasonable option in humid coastal areas. For direct waterfront exposure, asphalt shingles are a compromise, and a properly specified metal roof is worth a look.

Flashing

Flashing is the least discussed variable in a roof and one where material choice has a direct effect in salt air.

Galvanized steel flashing is standard on many roofs. In coastal air, corrosion at seams and cut edges can shorten its life compared with inland, so it is worth asking whether it is the right choice near the water.

Copper and lead-coated copper flashing are traditional choices for coastal and high-quality work: valleys, chimneys and step flashing at dormers. Copper resists salt air well.

Aluminum flashing is acceptable in many cases. One caution: aluminum in direct contact with some pressure-treated lumber can corrode, because of the copper compounds in the wood treatment. Use a compatible metal or a separation at contact points.

Standing-seam metal roofing

Standing-seam metal has become more popular on coastal homes. A properly specified installation can outlast other roofing materials and needs little maintenance. The specification matters.

Coating and base metal. Not all coated steel performs equally near salt water, and manufacturers publish different guidance for marine exposure. Aluminum panels are also used. Ask the manufacturer's marine-exposure guidance for the specific product before choosing.

Fasteners. In coastal applications the fastener is often the first weak point on an otherwise sound installation. Use stainless fasteners suited to salt exposure, and ask what grade is specified.

Summary

Match each material to the real exposure:

• At the water: copper gutters and leaders, copper or lead-coated copper flashing, and a metal roof specified for marine exposure.
• Near the water: heavier-gauge aluminum or copper gutters, shingles with realistic service-life expectations, and flashing that does not rely on galvanized steel at seams and valleys.
• Inland: standard specifications generally apply, and upgrading flashing at valleys and penetrations is worth considering.

Salt air does not attack all materials equally, and it does not affect all locations equally. If you would like a recommendation for your house, get a quote.