gluing composite lumber

[kulas44]

What kind of adhesive would a person use to lay a deck made from composite boards (Choice Deck, Trex, etc.) on a boat. I would prefer just glued and not screwed, as it will be over plywood. The info I have read says to use a good construction adhesive or polyurethane glue, like gorilla glue. I also read about a guy that used epoxy, but he also screwed it down. Any thoughts ?

[Bob Smalser]

Some of this stuff is full of gypsum and other adulterants that might not like glue, so I'd test it thoroughly first.

But between marine epoxy and poly construction adhesives like PL Premium, I believe one of the two will work. From my tests on it, PL Premium behaves more like a thick, gap-filling liquid poly than rubbery 3M 5200, is repairable with itself or epoxy, and holds up well to water saturation.

[kulas44]

Thanks Bob, great info. After doing some research I have concluded that this stuff would be like trying to glue something to a 5 gallon plastic paint bucket, not gonna work. However, a company called Plasteak, I think, has a different aproach. They use thinner planks that are t@g. Each plank has multiple dovetails cut into the underside that when layed onto thickend epoxy give a mechanical bond. each plank is glued in the t@g with a pvc glue which provides a molecular bond similar to pvc piping (waterproof). The product itself is most likely the same as everyone elses plastic wood, just way more expensive. I think I can use the Choicedeck and mill it on my table router. Any ideas ??

[Rod Tait]

You might want to look at a company called Tek Deck. They produce teak composite decking specifically for boats with all the info on how to apply.
http://www.tek-dek-international.com/

[kc8pql]

I've never used this stuff but I do have some experience with design for plastics. You need to consider thermal movement. Unlike wood that moves primaraly across the grain, plastics expand and contract equally in all directions. Just as an example, say you have a 32' deck. If the plastic expands 1/32" per foot with a 10 deg. rise in temp, which isn't out of the question, your 32' deck is now 32'1". Not a big problem for a deck on the back of the house, but maybe not so good on a boat.

Ken

[kulas44]

The tekdeck is very similar to what I have seen in my research, may be the same company. I will try milling some pieces of choicedeck (recently built a pool deck with the stuff, love it) that are laying around, and torture test it. I don't plan to do this part of the project until next spring so I have some time to experiment.