How Long Dock Pilings Last in Salt Water, and the Signs One Is Failing

It depends almost entirely on treatment. One large piling supplier puts properly treated wood pilings at 30 to 50 years or more, narrows that to 25 to 35 years on the Gulf Coast, and gives untreated wood there five years or less. The treatment it means is CCA at 2.5 pounds per cubic foot, AWPA use category UC5B or UC5C, and the reason for the Gulf number is warm, high-salinity water where shipworms and gribbles work fastest. [americanpoleandtimber.com]

Sleeves, wraps and caps slow the attack at the waterline and the top of the piling, which is why they show up on new docks and not just repairs. [decks-docks.com]

Those are supplier figures, not ours. Florida's warm water, high salinity and the splash zone at the waterline all push toward the short end, and no marine contractor can promise a number of years on a piling they did not treat.

Concrete and fiberglass composite pilings are not food for borers, so their service life is governed by corrosion of the reinforcing steel, impact damage and the connections rather than by biology. They cost more to buy and set, which is why most residential docks in the four counties we serve still stand on treated timber.

How long does the dock itself last? Usually less than its pilings. Florida owners report pressure-treated pine decking checking and splitting within about 12 months and ipe going around 20 years, so a dock typically sees at least one deck replacement on the same set of pilings. [thehulltruth.com]

Shipworms are not worms. They are bivalve mollusks that enter wood as tiny larvae and tunnel as they grow; UF/IFAS Extension describes burrows from 7 inches to over 6 feet long inside a single timber. The entry holes stay pinhole-sized, so the outside of a piling can look fine while the inside is riddled. [blogs.ifas.ufl.edu]

Gribbles are small crustaceans that work from the surface inward, and they concentrate at and just below the waterline. The result is the classic hourglass, a piling that necks down where the tide moves across it. [americanpoleandtimber.com]

Florida boaters put it plainly on The Hull Truth: the worms are real and will eat a pole like termites. [thehulltruth.com]

• Necking or an hourglass shape at the waterline, where borers and gribbles concentrate. [americanpoleandtimber.com]
• A lean or wobble under load. That is lost embedment or lost cross-section rather than a surface problem, and work on the part of the piling you can reach does not put the grip back in the ground.
• Soft wood you can push a screwdriver into, cracked or missing caps, and rusted or loose hardware at the stringer connections. The Forest Products Laboratory's probe test is the check: decayed wood is excessively soft, resists the probe little, and breaks brash and brittle where sound wood splinters. [research.fs.usda.gov]
• Scour at the mudline after a storm, or pilings that have been uplifted by surge, which changes the embedment even when the wood is sound. [dockdogsfl.com]
• A lift that has started to rack or bind, which often traces back to one of its four pilings rather than the lift hardware.

FEMA's mitigation guidance for coastal facilities sets the cadence: watch the at-risk parts against a known baseline, and judge the need for a closer inspection after a storm, at regular intervals — FEMA's example is every two years — and after any report of accidental damage, which a hard boat strike is. Submerged parts get an underwater inspection. [fema.gov]

Above water you can spot leaning, necking, soft wood and loose hardware yourself. Below water a diver looks for borer tunnels, probes the wood, checks scour at the mudline and tests movement under load. Warm water and heavy growth argue for looking more often, not less.

Lift pilings get the closest look because the lift concentrates the boat's weight on four points, and a piling that is fine for a walkway may not be fine for a loaded cradle.

Wraps are prevention. A wrap on a sound piling keeps borers and gribbles off the waterline zone; it does not put strength back into a piling that has already lost section. Do piling wraps work? On new or still-sound wood, yes, and suppliers list them alongside caps as standard protection. On a piling that is already necked, the answer is a jacket or a new piling.

SnapJacket is a UV-stabilized PVC jacket that fits around the existing timber piling and is filled with concrete. Its distributor states the concrete fill kills the borers inside the wood, fills voids to create a new solid piling, and can restore even broken pilings. [buildingproductsplus.com]

Because the jacket opens and locks around the pile, there is no need to remove or disturb the dock, lift or boathouse above it. That is the practical difference on a residential dock: traditional piling replacement often needs a barge and partial disassembly of the dock, and a lift piling means the lift comes off too.

Replacement is the right call when the piling has failed below the mudline, when the dock is being enlarged or re-engineered, or when you want to change to concrete or composite. Where erosion and scour are the concern, FEMA's coastal-facility guidance is a deeper pile: replace the deteriorated pile, or sister a new one alongside a pile still in good condition. A jacket adds no depth. [fema.gov]

Either way the state paperwork is light: installing or repairing pilings on a private dock is an exempt activity under F.A.C. 62-330.051(5)(a). The local building permit and any county review still apply. [law.cornell.edu]

A general home inspection stops at the seawall cap. Before closing on a waterfront home, have the dock inspected separately: the lift's rated capacity against the boat you will put on it, the dock electrical, and the pilings below the waterline. [millionluxury.com]

Ask the seller for permit history and any FDEP self-certification, and photograph the dock from the water. Langley Coastal's marine inspections include underwater photos and video, which is the evidence you want in hand before you negotiate.