Our PT Southern Pine dock is about 48 years old, with no planks replaced. (Only two flipped in its history). Construction on a neighbor's dock tells me it's the same contractor, and it looks somewhat better. How frequently it gets treated is unknown.
I never saw my dock when it was new--it's been gray "forever". I'd guess it was treated four times in its long history. (Three times by me.) 'Always used
Thompson's Sealer and used either a brush or a roller: The roller threw a lot of sealer, but the majority of drops landed against the adjacent boards' wide edges. (The brush was much harder to control the excess sealer).
There are only three issues that need attention:
1) Splinters
2) Vegetative growth on the dozen planks nearest shore
3) Resetting the nails
✔ Checked annually, and a few splinters are glued back in place using epoxy--temporarily held in place with doorstop-shaped wooden wedges. Sometimes removal or sanding will fix the occasional splinter. Always barefoot, i don’t have splinters as an issue, but some folks had that justified concern for their grandchildren.
✔ Vegetation is a recent condition, caused by too many oversized boat wakes crashing ashore. (Occasionally, wakes will soak a sun bather at the end of the dock.). So far, wood rot is not a problem. It's slippery there but fortunately, they're not in a well-traveled area. I need to re-treat those boards in spring, when it's relatively clear of vegetation and the weather is warm and dry. Maybe a day in late spring, when the sun heats the dock so it's too hot to walk on!
✔ Nails need hammering back in place: lag bolts need tightening.
After one episode of finding the dock submerged after "Ice-Out", I've chained the outermost
piling sets to the dock. Yes, a chain will occasionally break during Ice-Out, but the dock is saved from becoming a
floating dock!
Repairing with a farm jack:
https://www.winnipesaukee.com/forums...ead.php?t=1694