Marine or exterior ply for Karndean / Amtico subfloor?

19 Feb 2016
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United Kingdom
Hi, I'm prepping for my new Karndean floor and in the past my fitter has used 6mm marine ply as a subfloor. But as my lounge is now about 4 times as big as the last project I'm wondering if I can use exterior grade ply instead? This seems a lot more affordable. The description says it is waterproof but unlike marine cannot be submerged in water. I wouldn't have thought this was necessary anyway???

Looking forward to your thoughts.


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Best ply to get is SP101
If you can't get that then 9mm ply from Travis Perkins is ok.
Thanks for your quick reply - I'll see if I can get the 101 locally and how much it costs. Do you know roughly how it compares to marine / exterior grade ply?

And when you say 9mm from TP is this their standard ply or exterior?

Thanks again!
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It's the best on the market for gluing too. You will only get it form flooring suppliers or Hanson plywood

Not sure on the Travis one. Think its exterior. Hardwood throughout. It's about £20 for 9mm inc vat.

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