A few years ago I purchased three large wooden plant pots for our outdoor communal yard. The size is about 60 x 60 x 60 cm. At that time, I was advised to add thermal insulation, because the winters are rather cold here: -20°C is common, and -30°C is not unheard of. (Now I believe that this insulation would not actually change anything for the plants.) So the pot maker added layers of some kind of polystyrene foam to the walls, covered with some fabric.

After a few winters, the fabric became torn, and the foam breaks loose and on windy days it is sometimes a major source of trash in our yard. Apparently also local kids like to pick out pieces of foam.

So now I'm thinking on somehow sealing the foam to avoid further breaking. I do not need it to be very pretty, just not much uglier that it is now, the main thing is to stop further disintegration.

What would be the best way to do this? It should sustain winters as cold as -30°C with snow and (probably) ice cover, and summers as hot as 35°C with direct sunlight exposure for several hours per day. Also it should sustain curious picking by children. (I understand that with proper tools the children will be able to break anything that I can make, but I don't think the children are that malicious; they are just curious and thus will not break it if they see that it holds tight.)

I was thinking on adding a layer of some kind of epoxy glue, but I'm not sure how it will interact with the foam (will it stick to the foam? I've been reading that some epoxies can melt foam...). Also it is clear that a thin layer of epoxy will not be enough anyway, so I was thinking about creating some form from plywood or cardboard atop of the foam, and then pouring epoxy in it, similar to how they pour concrete into wooden forms. However, I'm afraid that the epoxy will not properly set in a thick layer, and that epoxy can stick to the form, not allowing me to remove the form later.

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1 Answer 1


Thin aluminum flashing will work. It is easy to cut and bend in fit over the foam.

If you want nice tight corners, a couple pieces of 1x2 or 1x3 clamped over the flashing will make them by hand.

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