which type of plywood for decking?

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wcoastwhacker

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so ive done some searching on this site and i've found several answers to this question and want some clarity...

i want to install a deck in my boat (pics to come) and dont know what kind of plywood/wood to use. some say STRICTLY marine grade with coats of waterproof sealant, and others say exterior plywood with coating will work. will either work? which is the cheaper way to go and where can i find this type of plywood/2x4's whatever i need? this is my first project so give noob details!

Thank you!
 
Marine Ply is exceptionally expensive-anywhere between $75-150 a sheet. You can use anything you want really, but DO NOT use pressure treated. Corrodes aluminum. I used stuff from Home Depot called "Home Advantage". It was cheap, like $20 a sheet, perfectly straight, and apparently will not absorb water at all. I still coated it with spar urethane, but its better to do it right the first time. If I could have afforded it, I would have used Marine Ply. Use the search function at the top of the screen and I guarantee every question you have can be answered quickly by people that have already answered them...
 
Currently I don't have the funds for marine plywood at that price so ill go ahead with the ply yo recommended along with the sealant. does th same go with 2x4's? Anythin will work as long as it's sealed?
 
Pretty much, just make sure its not pressure treated. Do some planning to get your bracing as efficient as you can (meaning as little of it as you can). 2X4's get HEAVY and take up a lot of space... If you have any metal scrap yards around you, go check them out for scrap aluminum angle. If you can get aluminum for fairly cheap, thats the way to go, its lighter than wood, wont rot, and is stronger. Just rivet it together.
 
If you're going on the cheap, use the exterior grade plywood (not that chip board crap). Seal the top side and edges only (you want the bottom side to be able to breathe).

You'll save a considerable amount of weight (important with small boats) if you'll do your framing with aluminum angle instead of 2x4s. You can buy the angle cheap at scrap yards and recycling centers. Use pop rivets to put your framing together with.

Installing vinyl instead of carpet will be more water repellent than carpet and will make your decking last longer.

Fastening your decking down through your vinyl or carpet will come in handy if you ever need to take your decking off to work on your boat.

Installing floatation foam under your decking is a good idea for safety purposes, you can use the pink or blue polystyrene sheets they sell at home depot.
 
SVOMike86 said:
Marine Ply is exceptionally expensive-anywhere between $75-150 a sheet. You can use anything you want really, but DO NOT use pressure treated. Corrodes aluminum. I used stuff from Home Depot called "Home Advantage". It was cheap, like $20 a sheet, perfectly straight, and apparently will not absorb water at all. I still coated it with spar urethane, but its better to do it right the first time. If I could have afforded it, I would have used Marine Ply. Use the search function at the top of the screen and I guarantee every question you have can be answered quickly by people that have already answered them...


Right on - I did not use marine grade and it is working just fine
 
thanks for the help guys! i plan on putting rubber drainage matting directly on the aluminum floor and using ply for the front and rear decking. instead of carpeting the decks i was thinking of a non skid paint directly on the wood. any recommendations?
 
Your boat more than likely has chines, which are the channels that run front to back. They serve pretty well for drainage. You shouldnt need to put any rubber matting on them, better bet is to put some floatation foam under deck like Jigngrub said. Better safe than sorry...
 
wcoastwhacker said:
thanks for the help guys! i plan on putting rubber drainage matting directly on the aluminum floor and using ply for the front and rear decking. instead of carpeting the decks i was thinking of a non skid paint directly on the wood. any recommendations?

I used Tuff Coat. Its a rubberized non skid that comes in a few different colors, I used Tan. It was a pain in the butt, and requres a primer coat. I do like the results but if I had to do it over again. I wouldn't! I would take it to the LineX place and let them do it. After I bought tape, rollers, mineral spirits, drop cloth, paint mixer, applicators I was in for what it would have cost to have lineX do it. Here is the boat I used the tuff coat on... https://www.tinboats.net/forum/viewtopic.php?f=3&t=20508

On my last boat I did the floors and front deck in exterior plywood with 3 coats of spar urethane. I used the Minwax brand Helmsman spar urethane in a spray can. I then painted the floor and decks with green Camo rustoleum and it was not slippery and held up fine. If it gets scratched or something you just spot spray it with more spray paint. You can see and read how I did it here....https://www.tinboats.net/forum/viewtopic.php?f=21&t=17299&hilit=swamp+sled
 
i just got back from home depot and purchased 3/4" red oak plywood for the deck along with a quart of helsman spar urethane for coating. will this plywood work well?
 
wcoastwhacker said:
i just got back from home depot and purchased 3/4" red oak plywood for the deck along with a quart of helsman spar urethane for coating. will this plywood work well?

No it won't, that's an interior grade plywood and doesn't have the water resistant glue like the exterior grade.
 
sounds like i'll be returning it tomorrow then....so white oak is the way to go?


i just called home depot and they do not carry white oak plywood.any recommendations?
 
Go to Home Depot and tell them you want 3/4 CDX plywood. It will be pine or fir. More than likely fir. The CD stands for C grade on one side and D side on another. The D side will be the worst side with unfilled knots so I would put that side down. The X stands for exterior grade and has a different adhesive than interior panels. Oh and a lot of plywoods have gone to 32nds for measurement. So 23/32 CDX is more than likely what you will find. Should be on the racks in front by the framing lumber.
If you still are having problems, go to a local lumberyard, not a big box store. Local lumberyards typically have a little more experienced help. Oh and most of them don't charge you to cut plywood for you if you ask!!! (Still can't believe how much the box stores charge for that service)
 
i looked at homedepot.com for CDX plywood and it says its pressure treated which according to this site is a horrible choice for aluminum. any other suggestions or input?
 
Ok. I looked at Home Depot's website and they have it listed as 23/32 RTD plywood. That's what you want. Store SKU #166103

Looks like they also have a product called DryPly. It has a water repellant treatment already applied. It does have a tongue and groove edge though and costs a little more.
 
i found the 23/32 plywood thanks for the input! BUT isnt pressure treated bad for aluminum boats? (it erodes the aluminum or something?)
 
That RTD isn't treated. It's just plain old pine plywood. RTD has to do with the glue up process of the veneers. It has an exposure 1 rating which is the same as CDX. Clear as mud right?

And yes for the most part treated will corrode your boat. The newer stuff (MCA) is supposed to be safe for metal contact. However, they don't recommend it on metal in areas that will always be wet (like a boat)
 
Hey all, newbie here and have been using the search function to answer most of my questions. So, before I buy, just wanted to re-confirm the following process for decking in my 16ft boat: 3/4" exterior plywood and coated with spar urethane? Also, after coating it with spar urethane, will I be able to use adhesive and carpet on it?
 
I used 3/4 in exterior grade plywood and coated it with epoxy. I covered it with outdoor carpet and riveted the deck to the rails that support the deck.
 

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