# Replacing pressure treated planks on a boat dock



## joecaption (Nov 30, 2011)

Does not really matter where you buy them, there all going to be wet and at least some of them are going to do something funky and need to be replaced in most cases.
There not powder coated there ceramic coated, there at least 1/2 the price of stainless steel, life time warrentyed and are also harder then stanless so there's going to be less cam out. (stripped heads).
Install them tight, once they shrink there will be plenty of room for dainage.
The best way to install them is with a impact driver. Once you try one you may never use your drill again.


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## woodworkbykirk (Sep 25, 2011)

your post says your in florida but is the dock in salt water or fresh water. if its salt water definitely stick with the stainless steel screws because the coating can wear off the threads when being driven and the bit on the driver will wear it off inside the recess of the head. salt water is 10x worse for causing corrosion on metal than fresh water. stainless wont rust

the other thing is that regular pressure treated isnt designed for immersion in water especially salt water. so if its going to be in salt water you should contact the lumber yard and see if they can get you marine grade pressure treated. theres a world of difference between the two types. 

im in a marine environment which is boat crazy.. ive built wharfs and decks on the water. ive seen what happens when you dont use the correct materials


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## FrankL (Jun 9, 2010)

It is brackish but more salt than fresh. The ocean inlet is about 1.75 miles away and the inland feeder canals are not really close. The dock builder used stainless. I called them and she said the marine planks are about $10 cost. The guy at Lowes said their better pressure treated will do the job. 

I deck will not get immersed in water. I have concrete pilings and the wood (underdock) at the highest tide is still about 10" away from the water. It is a quiet canal with no wakes. 

I will check into marine lumber. The dock company is about $20 a plank to do about 13 planks - wood and labor plus stainless screws. 

I was trying to save some money but maybe I should just let them do their job. Most of the planks are fine. Thanks. :no:


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## notmrjohn (Aug 20, 2012)

Some composite planks are rated for salt water exposure, about twice cost of marine PT, but lasts a lot longer, and they won't shrink or go "funky" on ya.

Some of the city built fishing piers and foot path bridges here are composite, some PT. Most of them have more or less free floating plank ends. The ends are slid into fairly snug, heavy steel U channels or under angle iron on beams. Some of the narrower bridges and piers are not even fastened to beams along center. This may just be so that planks make nifty noise when kids ride bikes over them, also warns pedestrians that speed demon is coming. They wait a year or so, then come back, flip and flop bowed and cupped planks, replace badly warped ones, shove and pry them all tight to each other and shoot a bolts thru steel and planks, usually just at ends of pier or bridge.

Granted this is not salt water. Salt resistant Bridge Steel is pro'lly way expensive. But idea of looser initial fastening ( wooden angles on beams) could save labor time later when dealing with planks that have gone all funky. 

Shrinkage gaps between initially tight planks, if not too wide allow water to drain thru quicker, less chance of trapped water starting rot. Dryer deck, less chance of crew falling on their afts.


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## user1007 (Sep 23, 2009)

This is not a proposition where savings up front is really going to translate well long term. You will end up paying the piper more later and just be replicating your labor sooner than you should have to. 

Definitely use real lumber yard marine rated treated planks. And stainless, not coated screws anywhere near salt water. I don't think looking into the more expensive composite dock materials a bad idea either with the idea of phasing them in over time?

As for coating it. You should check with the lumber yard but most treated timber cannot be finished for 3-6 months. Whether you decide to do so at all depends on how critical aesthetics are I guess. A dock is a dock. On the other hand if you are mooring a scale model of the Queen Mary you may want something a little glitzier.


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## woodworkbykirk (Sep 25, 2011)

just a case in point example.
a few years ago we installed a steel cable hand rail system on a deck that was right on the ocean. the homeowner is actually a architect who designed it. he spec`d galvonized even though we advised against it due to the corrosion factor of salt water.. he didnt want to spend the money on stainless.. 8 months later we were back replacing it all with stainless because every inch of the galvonized was rusted


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## FrankL (Jun 9, 2010)

Thanks gents. I would probably let the dock builder do the job. I may check the local lumber company to see if they have the real deal there. They said it was on the phone. I think it was $17 a plank for a 12 foot plank. 

When I had it built about 6 or 7 years ago, I had them do concrete pilings. At the last minute I asked if I could switch to composite and they said it was too late. They spec'ed everything for a wood deck. 

Lowes and HD have composite but they will not do any cuts and it was something I was not going to try. I also did not want to mix and match with wood. Thanks again. :thumbsup:


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## notmrjohn (Aug 20, 2012)

"Thanks *gents*" When will folks learn that we are ruffians?

" they will not do any cuts" yet another opportunity to buy a tool is lost. Frankly, cutting planks with a skil-saw and speed square is way easy, Frank. You can't be that much of a klutz if you can handle a boat.
I don't understand how it can be too late to switch to composite planks. Possibly joist spacing needs to be 16" instead of 24", but that has nothing to do with pilings. Unless joists are directly on pilings instead of beams.
I think that even with buying saw and using composite you'd still save over hiring it done. 

And you have saw to do other things. Like repelling boarders.


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## FrankL (Jun 9, 2010)

notmrjohn said:


> "Thanks *gents*" When will folks learn that we are ruffians?
> 
> " they will not do any cuts" yet another opportunity to buy a tool is lost. Frankly, cutting planks with a skil-saw and speed square is way easy, Frank. You can't be that much of a klutz if you can handle a boat.
> I don't understand how it can be too late to switch to composite planks. Possibly joist spacing needs to be 16" instead of 24", but that has nothing to do with pilings. Unless joists are directly on pilings instead of beams.
> ...


Thanks Ruffians. :laughing:

Yeah - I did not get why they said that. Maybe they ordered the wood already. I was in Lowes sort of weighing the weight difference and they seemed about the same. I think they have Trex and it was GA Pacific pressure treated wood. The weight is about the same. 

I will check the dock company who built it. 

Me and boats? I rent the dock. Boats are a hole in the water to pour money into. I am Gilligan. I once swamped a Boston Whaler in a very tricky inlet.


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## notmrjohn (Aug 20, 2012)

Algae may grow more readily on composite planks than PT, at least in beginning, eventually the chemicals in PT will "weaken" and growth will be as liable on one as the other.

So that's what a boat is. It seems to be the opposite of an aquarium. A glass box full of water into which you throw money.


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## FrankL (Jun 9, 2010)

notmrjohn said:


> Algae may grow more readily on composite planks than PT, at least in beginning, eventually the chemicals in PT will "weaken" and growth will be as liable on one as the other.
> 
> So that's what a boat is. It seems to be the opposite of an aquarium. A glass box full of water into which you throw money.


The guys on Lowes were *****ing about mold/algae on the Trex stuff.. I get sunlight all day so it should not be an issue. I also have a brisle brush. 

I sealed the wood with a good latex based sealer for Florida. Hands and knees stuff with one of those painting pads but the wood was beautiful when it was done.

Well this Boston Whaler was swamped so it became an aquarium. This inlet has concrete walls on each side and it only about 50 feet wide. When the tide is going in and out - the water rushes through at about 25 mph. Scary stuff. 

Thanks. :thumbsup:


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## FrankL (Jun 9, 2010)

One more question - Gents, Ruffians, Ladies (if we have any here) and any slackers. 

I unscrewed the stainless screws (still in great shape) and pulled out the rotted board. I have a few but this one was the worst. The ones that rot the fastest are the planks that slip under the wood wrapping the concrete pilings. The water from the rain must pool under there. 

What do you recommend that is cheap to full in the old screw holes of the framing before I screw down a new plank? That epoxy wood repair stuff or just liquid nails or what??? Thanks for all the help. 

:wink: :thumbup:


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## notmrjohn (Aug 20, 2012)

" the planks that slip under the wood wrapping" that shoots down my idea of putting similar hold downs around entire dock. plus people would trip over it and fall in water, splashing it all over new deck as the thrash around in panic.

Instead of filling all the holes, might want to drill some all way thru to drain water. If possible, as i don't really know how pi;ings are wrapped. Drill thru plank and frame underneath. If wrapped piling extends above deck, maybe raise wrapping an inch or cut off bottoms to keep water from being trapped? Cut new planking a bit short where it butts against piling under wrap so water drains off ends. 

The holes you want to fill are in framing under planks? Old PT, so oozing of chemicals has stopped? Some folks do use liquid nails as a "caulk" on decks. I dunno how it would stand up under the wet conditions. Epoxy or good silicone caulk would probably work, and mite be good idea to have it proud of surface, no dip or depression to hold water. Marine supply might have a better caulk or filler.A paintable one would be nice. Clean and scuff frame with coarse sand paper, slap some oil base over fills and top of frame that won't be seen, can't paint silicone so paint first then fill.


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