Redoing a deck

[Medic4040]

I was told to redo my deck using 5/8" A/C Fir, as opposed to using marine grade or even pressure treated plywood, any thoughts?

 

[zach103]

Re: Redoing a deck

i would go with marine just cuz we all know that it holds up like it should. you dont wanna have to do it again next year.

 

[Medic4040]

Re: Redoing a deck

I do plan i fiberglassing the deck and then putting down the rug, still go w/ marine grade

 

[109jb]

Re: Redoing a deck

What kind of boat? Aluminum or fiberglass? In any case, 5/8" AC exterior grabe is fine.

I did my Starcraft Aluminum with Pressure treated 5/8" plywood, but you have to do something to keep the aluminum and PT ply separated. I used rubber strips glued on top of the aluminum stringers. You can go with the regular non-treated exterior plywood and it will last fine as long as you take care of the boat.

For my fiberglass Sea Ray, I will be using Exterior grade plywood, and will fiberglass all sides of the wood. You can use PT ply here too, just have to dry it good so that the glass will stick.

 

[erikgreen]

Re: Redoing a deck

This is one of those questions with deeply divided answers... like asking which is better, Mac or PC... or which oil to use


Bottom line: If you're fiberglass coating it, then it almost doesn't matter what wood you use EXCEPT for its moisture content and anything else that might keep resin from adhering. PT wood is soaked in preservative and usually not re-dried afterward.

For a deck, most people coat only one side with glass when using epoxy, so the stiffness matters, in which case more plys is better, IE furniture grade or marine grade.

If you're coating both sides with a layer of glass, then all your strength will come from that anyway, so it doesn't matter if you use exterior or marine grade. For that matter, you could use interior grade or OSB if you really wanted to.

I won't go into the differences between types of wood again, but basically marine grade has more layers (plys) no voids (air spaces) and uses a better glue than exterior grade (sometimes the same glue). All these make it somewhat stronger/stiffer, and no voids means no places for condensation/seepage to collect. This is good for a boat to have.

Exterior grade can be almost as good as marine grade, depending on various factors. The best exterior grade is better than the worst marine grade, but generally marine is a bit better quality... and you pay dearly for it at most places.

By all means, use marine grade if you wish and can afford it, it's quality stuff. But don't suggest that exterior grade won't last a year... properly covered with glass and epoxy and waterproofed, the cheapest grade of plywood will last longer than you'll own the boat, and then some.

Remember, if it's covered in glass, it's just a composite core... it could easily be balsa wood or foam instead of ply (except in a transom, of course).

Erik

 

[maxum247]

Re: Redoing a deck

If your not using marine plywood use the best exterior grade plywood you can find.

 

[Solittle]

Re: Redoing a deck

If your concern is wood rot down the line forget the carpet or rug. They take forever to dry out. Use a good quality marine poly with speckles or whatever instead of a rug.

 

[Medic4040]

Re: Redoing a deck

Thanks for the input guys

 

[Bondo]

Re: Redoing a deck

properly covered with glass and epoxy and waterproofed, the cheapest grade of plywood will last longer than you'll own the boat, and then some.

Ayuh,.... Exactly.....

And, I'll add that 5/8" is Too Thick if you're covering it with Glass,+ resin.....
1/2" is Plenty if you're coating it....

 

[NSBCraig]

Re: Redoing a deck

There really is no reason to use anything but 1/2" plywood (regular old plywood).

I really don't understand why people think pressure treated is better in anyway. There is no way to truly dry out a piece of wood that has been soaked in a tank under pressure. It's not what the product is made for in any way. Not only are you gonna have to worry about your resin adhering but your starting with wood that has some moisture in it which is what you don't want.

Like erik said wood is a core seal it with resin and glass and it will last, don't seal it and it wont wether you use marine grade or not.

I had a friend who used to make new pieces to replace his seats etc every year using marine grade and complained constantly about the cost and hassle who just wouldn't believe all he had to do was seal it.

 

[frank england]

Re: Redoing a deck

I agree... Just use reagular ply wood and paint it with porch and deck paint (2 coats)will last for years

 

[oops!]

Re: Redoing a deck

eriks is a very good post.......

im sorry we dont feel like typing the same stuff for the different typs of plywood over and over......

just hit search.......plywood.....drying plywood....ect.....there is 10 years of detailed information.

but eriks post sums it all up

just one other point......it is YOUR boat.....YOU can put any kind of material you want in it

 

[seven up]

Re: Redoing a deck

I was told to redo my deck using 5/8" A/C Fir, as opposed to using marine grade or even pressure treated plywood, any thoughts?

Fir plywood will "check". So using just paint and working towards a smooth painted surface is questionable at best.


and could you enlighten everyone on which sort of deck and boat this might be

10ft Walker Bay ? 80ft Azimut ? Foredeck ? Sidedeck ? Afterdeck ? Poopdeck ?

Anyway, I wanted you to know about one of the famous properties of fir plywood.



Enjoy

 

[Medic4040]

Re: Redoing a deck

pardon my ignorance but what is "checking"?

 

[maxum247]

Re: Redoing a deck

Cracks and splits in the wood surface.

 

[sschefer]

Re: Redoing a deck

There is some good advice here if you manage to weed through it all. Here's the real skinny.

Water Resistant Oriented Strand Board - very poor impact strength and highly succeptabe to moisture collection. Not a good choice unless fully glass encapsulated.

Medium Density Fiberboard - Same as above but not water resistant.

High Density Firberboard - Same a above but with 5 times the weight. Expensive.


Pressure treated. This only protects against bugs and is not waterproof. It is made with water resistant glue but contains many voids. So, not a good choice.

Cabinet grade 15ply birch - No voids, only hardwood on exterior surfaces (outer ply's) can have voids but are minor. Is not made with water resistant glue. Plys are thin and can separate if finish is not done properly or it is compromised.

Marine Grade 5 or 7 ply - No or filled voids, assembled with water resistant glue, is expensive but is normally stored inside and protected during transit from mill to yard. This means that it's dry and is usually ready to cut from the yard. It is also warp resistant due to zero voids and lower mositure content.

Using Marine grade ply is the best choice but not always affordable. If you use a cabinet grade ply and paint it with "Copper Green", then Zinser 123 and finally a good coat of exterior enamel paint that will be enough to thwart off the bugs and dry rot for about 10 years if you make sure to vent the bilge(s).

During long term storage or even during the winter a simple blower fan can save you many headaches down the road.

 

[Stoutcat]

Re: Redoing a deck

Thank you sschefer!!!

Here's more of the bottom line (speaking as a wooden boat builder)...

- Type of ply for deck? It depends... If you're going to take your boat out in the summer and cruise around the lake then store your boat inside between trips and in the winter... Who cares? Just as long as there's some UV-protected epoxy on the deck and some ventilation below, you'll be fine.

- If the deck is going to see prolonged wetness (carpet, etc.) use marine ply and thorough epoxy.

- T'ain't no way to "encapsulate" wood. Water just finds a way. The best defense is a strong ventilation offense.

It's been a while since I re-decked a boat, but if I had to do it again, I'd go the route of PT dimensional stringers, pt laminated ribs and poly wood decking complete with gaps...

And laminating ribs is no more difficult than laminating the handle of this tool box. Some wood strips, epoxy, thickener, a pattern, clamps, time, and there you go. (Just don't let the wife decide that it would make for a better book box handle than a boat rib... Doh!)

Alan

 

[JaSla74]

Re: Redoing a deck

I'm a newb, so my input is newb at best. However, I'm in the middle of stringer, transom, deck rebuild. My boat is over 20 years old, but the ONLY wood that has any bite left in it is the dimension wood. ALL is the ply is complete mush... I can take it out with my fingers. The only thing holding it up is the glass.

Speaking with a local boat builder with 35 years of experience does not recommend ply (for the stinger anyway). His experience is that when the water does find it's way in the rot continues throughout ply. Whereas the dimensional tends to rot mainly where the water first finds its way in instead of carrying throughout the entire piece (although I sure it would should there be enough water).

If were up to me I'd go composite material all the way, but it's either way too expensive, or way too heavy.

 

[sschefer]

Re: Redoing a deck

One thing to know about composites, (non carbon fiber or kevlar) is that most are made from a flour mix of wood (sawdust from many sources) and recycled plastics). That flour can and has been proven to contain mold spores that will surface over time. Trex has a number of lawsuits still pending concerning this.

 

[sschefer]

Re: Redoing a deck

Beautiful piece of work Alan. It's nice to see hand cut dovetails. Shows a lot more class than using a jig. I'd have given you just as much credit if you'd used a Leigh Jig though. Anyone that can master setting up that jig should get the medal of honor. Off the subject a bit but I watched Norm try to set one up on the air. I think it was the longest segment they ever shot and yes, I have one in my shop somewhere. When aluminum gets a little bit higher I'll scrap it.