Everything else on your dock is replaceable. Boards come off, handrails come down, hardware gets swapped. The pilings are the dock.
Which is why it is strange how little attention they get. Most people have never looked at their own pilings below the waterline. That is the exact place where the dock’s remaining life gets decided.
What actually attacks a piling here
Three things, and they work in different zones of the same post.
The tidal zone. The band that goes wet and dry twice a day is the hardest-working part of the piling. Constant wetting and drying, plus sun, plus salt crystallising in the grain, breaks wood down faster than either full submersion or full exposure. This is where you will usually see the damage first.
Marine borers. Our brackish water hosts organisms that eat wood from the inside. The outside of a bored piling can look almost normal while the core is honeycombed. This is why tapping and probing a piling tells you more than looking at it.
Mechanical damage. Boats hit pilings. Debris rides in on storm surge. Ice is not our problem but floating logs and runaway floats absolutely are. A struck piling can be cracked well below where you can see.
So how long do they last?
Honestly, it varies enormously, and anyone who gives you a flat number has not seen your creek.
What moves it: the treatment level of the timber when it went in, how much of the piling sits in the tidal band versus buried in the bottom, salinity where you are, how much boat traffic and wake the dock takes, and whether anyone has maintained it.
A properly treated, correctly driven piling in a sheltered creek can serve for decades. An undertreated piling in a high-energy spot can be in trouble in a fraction of that. We have pulled pilings that looked fine and were hollow, and we have found forty-year-old pilings that were still sound.
The only way to know is to check yours.
How to inspect a piling yourself
Go at dead low tide. You want as much of the piling exposed as you can get. Take a screwdriver or an awl and a flashlight.
- Look for a waist. A piling that is narrower at the waterline than above and below it has been eaten. That hourglass shape is the classic warning sign.
- Probe the wood. If the awl sinks in easily, the wood is soft. Sound wood resists.
- Tap it. A solid piling rings dull and firm. A hollow one sounds noticeably different, and you can usually hear it.
- Sight the line. Stand at one end and look down the row. Pilings should be plumb and in line. Any that lean, twist or sit out of the row have moved, and pilings do not move for good reasons.
- Check the connections. Look at where the framing bolts to the piling. Elongated bolt holes, crushed wood around the hardware or rust streaking mean load is being carried badly.
Do this once a year and after any serious storm. It takes twenty minutes and it is the highest-value thing you can do for your dock.
When a piling can be saved
Not every bad piling means a new one. Depending on where the damage is and how far it has gone, there are real options.
A piling that is sound below the mud line and damaged in the tidal band can sometimes be sleeved or wrapped to arrest further loss. A piling carrying load badly at the connection can sometimes be sistered, with a second member driven alongside and the framing tied into both. Pile caps and jackets have their place.
What we will not do is wrap a piling that is structurally gone and call it fixed. That is the kind of repair we wrote about in repairs that almost never work. It looks like a solution for about two seasons.
When it has to be driven new
Replacement is the answer when the piling has lost real section in the tidal zone, when it has moved out of plumb, when the core is hollow, or when several pilings in the same area are failing together.
Driving a replacement piling next to a standing dock is skilled work. There is a structure in the way, the tide is on a clock and the new piling has to go in properly rather than just deep enough to stand up. Depth, spacing and material get determined on site for your conditions. We do not publish those as numbers, because a piling installed to a generic spec is how you end up doing this again in five years. The how and why of doing it right is in pile driving done right.
If most of them are going, stop replacing them one at a time
This is the part where we talk people out of work.
Individual piling replacement makes sense for one, two, maybe a handful in an otherwise healthy field. Once you are replacing a large share of them, you are spending more than a new dock would cost and ending up with a structure of mixed ages that will need attention again unevenly.
At that point the honest recommendation is to plan the rebuild. We walk through how to make that call in repair or replace.
Get a real look at yours
If your inspection turned up something you did not like, or if you have simply never looked, we will come out at low tide and go through every piling with you. You will get a clear picture of what you have and how much time is left in it.
See our maintenance and repairs services, or get in touch.
