Why coastal corrosion is different
Ordinary outdoor weathering is intermittent: things get wet, then they dry, and corrosion happens during the wet part. Salt changes that. Airborne salt aerosol settles on every exposed surface and forms a film that is hygroscopic — it pulls moisture out of the air and holds it against the metal even when everything looks and feels dry.
The result is that a coastal fixture is corroding most of the time rather than occasionally, and the process is electrochemical rather than simply oxidative because dissolved salt makes the moisture conductive. That is why coastal properties see failures that look premature by any inland standard, and why the answer is different materials rather than better maintenance alone.
How far this reaches is a question people want a number for and there is not an honest one. It is worst within a few blocks of the water and it carries considerably further where wind comes in off the ocean unobstructed. If exterior metal in your neighbourhood blooms white or streaks rust sooner than seems reasonable, specify for the coastal case regardless of what a map says.
What actually fails, in order
The visible finish is usually the last thing to matter, which is why people are surprised by the failures.
- FASTENERS FIRST. A small screw has very little material to lose before it loses its head or seizes solid. This is why fixtures become impossible to open before they become impossible to use
- SOCKET AND LAMP CONTACTS. A film of corrosion is enough to cause flicker, intermittent operation, or failure — and enough to generate heat at the contact
- GASKETS AND THEIR SEATS. Once a seal is compromised, water enters the housing and everything inside accelerates. Gasket failure is usually the event that turns slow decline into a dead fixture
- SUPPORT AND MOUNTING HARDWARE, which is a safety issue rather than a performance one — a working fixture with failing mounts is still a problem
- THE HOUSING itself, generally last, and generally only after the coating has been breached somewhere
Galvanic corrosion, or why mismatched parts fail
Put two dissimilar metals in contact with moisture between them and you have made a small battery: one metal corrodes preferentially to protect the other. In salt air, where the moisture is conductive, this happens briskly.
The pairing that shows up most is a stainless fastener in an aluminium housing, where the aluminium around the screw is consumed rather than the screw. It is also why a fixture repaired with whatever hardware was to hand fails around its fastenings within a season or two, even though the replacement screw looked perfectly good. Compatibility between the metals matters as much as the quality of either one.
What survives
- SOLID BRASS AND COPPER — they corrode to a stable patina rather than degrading structurally. They stop looking new quickly and then last a very long time, which is the trade coastal properties have always made
- MARINE-GRADE 316 STAINLESS — meaningfully better than the more common 304 in salt air. On fasteners specifically this is worth insisting on: they are small, cheap and first to fail
- POWDER-COATED ALUMINIUM — good while the coating is intact, and worth inspecting for chips, because a breach concentrates the attack
- PLATED STEEL — the one to avoid. Indistinguishable from better material on a shelf, and once the plating is scratched it fails quickly
- GASKET MATERIAL — silicone generally outlasts cheaper compounds outdoors, and gasket quality decides whether the inside of the fixture stays dry
Sealed or serviceable?
This is the design decision worth thinking about rather than defaulting on.
A SEALED integrated LED fixture keeps salt air out of the socket entirely, which removes the single most reliable failure point. The cost is that failure means replacing the whole fixture rather than a lamp. A LAMP-REPLACEABLE fixture lets you change a cheap consumable, at the price of a socket the environment can reach and an opening that depends on a gasket and on fasteners you may not be able to undo in five years.
Near the water, sealed usually wins, because socket corrosion and seized fasteners are so dependable. Further back, replaceable is often better economics. Neither answer is universal and anyone who tells you otherwise is selling one of them.
The wiring, which matters more than the fixtures
A corroded fixture is an annoyance. A corroded connection is a different category of problem.
Connections in wet locations belong in enclosures rated for the location with their gaskets intact, and corrosion at a connection does exactly what corrosion at any connection does: raises resistance, generates heat, and gets worse as it goes. Exposed conduit, fittings and support hardware corrode alongside. On coastal properties this deserves periodic attention rather than waiting for a symptom, because the symptom for a connection is heat rather than a light going out.
Outdoor receptacles need GFCI protection, weather-resistant devices, and IN-USE covers — the deep kind that keep water out while something is plugged in, rather than flat flaps that only seal when empty. That last detail is the one most often wrong, and it matters because the entire premise of an outdoor receptacle is that something will be plugged into it when it rains.
It is not just the lighting
The same environment works on the exterior equipment that matters considerably more than a garden light: the combination meter main, any exterior panel or disconnect, and their enclosures. Corrosion on service equipment is a routine finding near the water and one of the things we look for by name during an inspection. Where a property sits close enough to the ocean for it to matter, corrosion-zone hardware on that equipment is a specification decision rather than an upsell — and fixtures failing early are the visible early warning that the condition applies to your address.
This is why the neighbourhoods where we see it hardest are the ones you would guess: Pleasure Point, Capitola, Rio del Mar, La Selva Beach, Seabright, Twin Lakes and Davenport. Anywhere the wind comes off the water without much in the way.