Thread: Exterior or marine ply?

Treated pine would look good too. Use some Galvanised batten screws to hold it all together. You could also stain it.

Cheers
Pulse

My understanding of the marine ply is that it's mainly a grading thing, it has 2 good faces. So the inside and outside of your boat both look good
For your planters you only need one good face so exterior treated ply with one good side will be OK. I'm not sure how your ply is graded, but appearence is part of the grade.

Otherwise make em out of treated pine decking timber, splash out on a jar of stainless screws and it will last for years

Cheers

Ian

I'd strongly recomend against ply of any sort for this use. You will get better durability from one of the decking hardwoods.
I love ply but it has inherant problems in the elements.
Marine ply (AS standard) has good plies & no voids all the way thru and is quite expensive. Structrual CD is OK in the weather in the short term but eventualy the grain opens up & the finish fails which opens up the grain......
Merbau, Jarrah or similar will survive without finish, even better with.
cheers

I believe that the glues used in marine ply are waterproof marine tolerant ie resorcinal formaldehyde etc. and are a step up from the glues used for exterior ply. Marine ply is a great product, but very exxy. If cost is an issue, then you're probably better off using some good Australian hardwood or even CCA pine.

Actually the glues used in marine and exterior plies are identical ("A" bond) and Australian Standards specify that they must withstand 48hrs in boiling water. The difference is in the quality of the veneers. However I don't think either would be suitable for making planter boxes out of. If you really want timber then I suppose treated pine would be the go. I'd be exploring different materials like compressed cement sheeting, fibreglass or plastic.

Mick

I'd be exploring different materials like compressed cement sheeting, fibreglass or plastic.

Mick[/QUOTE]


old recycled timber can look good too, if it's hardwood it will last a while as well...

I used 1/2" exterior ply as a floor on the back of my hilux. I lasted six years only because I dropped a 44 gallon drum of water on it and busted the ply. Mick is right when he says the only difference between exterior and marine ply is the quality of the veneers. I thought the glue (type A bond) was required to withstand immersion in boiling water for 72 hours, but the standard may have changed.
Jim

journyman Mick,

Interesting about the glue, it would have to be pretty good to withstand 48hrs in boiling water.

The difference is in the quality of the veneers
I thought also that the species of the veneers was an issue ie. durability Class 1 etc.

I also agree that compressed cement sheeting would be a better material for that purpose.

Island Nomad,
never actually tried sitting it in boiling water for 48/72 hrs (Jim's probably right, it's been a while since I read the specs). The veneers in marine ply can't have any tears or voids, while with exterior plies this only applies to the face veneers. There's a very good marine ply being made from Hoop pine, which I'm pretty certain isn't durability grade 1. Ply in a boat isn't really meant to get wet anyway, as it will be protected by a paint or resin system and if it does get wet it will be with salt water which will preserve it to an extent. In this regard a planter box is a much harsher environment for timber than a boat. Cyclical wetting/drying and lots of decay organisms and wood eating parasite thingies.

Mick