My rooftop sandbox is flooded, smells bad and mouldy?

Question

My wooden sandbox is situated on the rooftop and sits on the wooden decking. It has a wooden cover but no drainage. I live in Shanghai and it's the rainy season now and typhoon season next. Now it's flooded and the bottom (where it's in contact with the base) is smelly and mouldy. What should I do now?
I was thinking of using covering the base and the top with ground sheets (vinyl) so the sand will not come into contact with the wood and it will also prevent water from entering the box.
Many thanks for your help.

Answer 1

I'm afraid your plan will not remedy the situation. It does not address the real issue, and that is the moisture that remains trapped in the sand and is providing a home for bacteria and fungi.

The sand must be elevated off the deck enough so that water can drain through it and air can move around it to keep it dry. You must also have a roof structure of some sort to keep the water off. With good drainage and air movement, and no new moisture added to the sand, it should dry out in short order.

A sturdy screening material, properly supported and elevated off the deck might make a good base for your sandbox.

Good luck!