# Forum Home Renovation Pools, Spa & Water Features  advice on marine ply for spa cover

## lolichka

Hi All,
I am after some advice please on marine ply (up-to 12mm thick) to make a spa cover. The spa is an octagonal shape and will be lifted via a pulley system and we'd like to keep it in one piece. We just want it to be a basic cover to keep debris out - nothing fancy. 
I do know that there are various types of marine ply but not sure specifically which one we'd need to make this. The spa is mildly chlorinated not salt if that helps. 
So ... 
1. which marine grade ply do I use?
2. where can it be sourced from in Melbourne (close enough to the mornington peninsula)
3. Is there anything else we need to do to the ply i.e. laquer it and if so in what? 
i'm sure there will be other questions but this will get me started in the right area  
I really appreciate the advice here... 
Thanks,

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## Oldsaltoz

marine ply is very expensive and for this application you could use builders exterior ply, still not cheap but a lot less than marine grade. 
If you think it might get wet at some time, you should consider a coat of epoxy based paint to protect it. 
Hope this helps. 
Good luck. :Smilie:

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## lolichka

> marine ply is very expensive and for this application you could use builders exterior ply, still not cheap but a lot less than marine grade. 
> If you think it might get wet at some time, you should consider a coat of epoxy based paint to protect it. 
> Hope this helps. 
> Good luck.

  Thanks very much for the reply... I'd imagine it would get wet perhaps from condensation inside the lid when its on the spa that may be a factor, rain as it would be exposed to the elements too.  
I'm looking at alternatives now instead of water proof type paint coating and may opt for marine grade vinyl instead.  
If I do choose to go with covering the lid (bottom/top/sides) in the marine grade vinyl, do I still need to coat the ply with a water proof type sealant although it will still be contained within the waterproof vinyl?? hope that makes sense... 
thanks  :Redface: )

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## Oldsaltoz

Sey it will need to be sealed.

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## cherub65

What ever you construct it from it needs to be higher in either the center   or one end to allow run off.  Personally would get aluminum frame made, cover with thin ply then wrap in vinyl to reduce weight

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## brettsyoung

You don't need marine ply. Marine ply is ostensibly just normal ply with more glue - ie it doesn't have the cavities between sheets of normal ply (if that makes sense) where moisture can gather. I would think a sheet of cheap ply with a few coats of quality outdoor paint would do. You would only need to epoxy (fibreglass) if using on a boat or if it's going to get knocked around. But even then that's only if you need to depend on maintaining the integrity of the timber to support a greater structure (or keep you out of the drink). If yours gets ugly in a few years just paint it again.

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## China

Spa's are normally insuslated with 100m of foam to to retain heat, if you replace a insulated cover with one of just ply the heating cost will skyroket, plus red your council regs (If that concerns you) some councils have  striked rules

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## lolichka

> You don't need marine ply. Marine ply is ostensibly just normal ply with more glue - ie it doesn't have the cavities between sheets of normal ply (if that makes sense) where moisture can gather. I would think a sheet of cheap ply with a few coats of quality outdoor paint would do. You would only need to epoxy (fibreglass) if using on a boat or if it's going to get knocked around. But even then that's only if you need to depend on maintaining the integrity of the timber to support a greater structure (or keep you out of the drink). If yours gets ugly in a few years just paint it again.

  thanks for the reply there... i've finished putting up the pool fencing around the spa so unless our 3 and 2 year old & 10 month old can hurdle over that then regular ply and some outdoor paint sounds like the way to go. I only have to worry about hubby falling in while he is cleaning it LMAO ... which he has done!  
Cheers,
L

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## lolichka

> Spa's are normally insuslated with 100m of foam to to retain heat, if you replace a insulated cover with one of just ply the heating cost will skyroket, plus red your council regs (If that concerns you) some councils have striked rules

  the spa heater is gas outside and is never left on for the sake of wasting gas and electric. We only turn it on when needed so don't have to worry about retaining heat. We bought the house with out a cover for the spa and have been using one that hubby made out of treated pine 1/2 round posts and builders plastic stapled to it LOL (which has served its purpose well! But now it's time to upgrade it a little  :Yikes2: 
cheers

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## wombat200

> You don't need marine ply. Marine ply is ostensibly just normal ply with more glue - ie it doesn't have the cavities between sheets of normal ply (if that makes sense) where moisture can gather.

  Incorrect. 
Under Australian Standards, Marine ply uses the same water-proof glue bond as exterior grade ply - and all non-exterior grades of ply use a different (non-waterproof)  glue. 
In addition, the veneers used in Marine ply are strictly governed, to provide maximum structural strength - after all, this stuff is being used for boat hulls, which you don't particularly want to fail in service....  So, Marine ply is usually A-A grade - so, A-grade veneers on the faces AND in the core. The number of knots, splits & patches (and the sizes of the patches) is also specified. 
Note that Marine ply is not 'rot proof' - it can still rot, just like any other timber, so it needs painting / preserving. That said, you can now buy rot-proofed marine ply (treated), but it's very, very expensive...... 
Standard Exterior grade ply would be the pick for this application, Marine ply is over-kill, as the strength requirement is not there......

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