Thanks, I agree. I don't like the quality level and price level combo of construction here so, I do it myself. I'll be doing an apartment that has nothing毛坯房 in the next month for a friend. starting from zero will be a fun project. I will keep posting progress on that one.
Sorry to say my friend the landscape architect confirmed that landscaping fabric is used only extremely rarely in China. If they get weeds, they hire a lady and she digs em up. Erosion control although a major problem for any construction firm, would really only be applicable for major government projects where they are responsible for large areas of dirt after the construction is over. As you've seen when construction is over in china very little open field is left.
That's not too say I won't see it tomorrow or quit asking about it. I'll let my OCD run point and if it's here I'll find it but it might be far too late for your sandbox. Can you post pictures somewhere when you're done and show us all your project?
All good questions. You have me a little scared with plywood on the bottom of your sandbox. The answer is a resounding yes it need to be sealed. Plywood, in its construction is wet and needs to dry properly to be used for anything. If it is in a wet location I'd give it two to three months before it's covered in black mold and likely moss. Kunming is pretty dry, I don't have any long term experience with it here. To correct this potential issue, perhaps, covering it with plastic leaving just holes big enough for the drainage you mentioned, could keep enough moisture out to avoid mold, but yes pressure treated plywood is a better fit, but far better would be to avoid plywood. Perhaps make the bottom out of pressure treated boards leaving a little room between them and then laying the fabric. I did not see green plywood out at the market on 雨龙路, however if it is available it would be at the specialty lumber market mentioned above for tigertiger. 1.2x2.4 is pretty big and as far as I know, no there isn't anything bigger. I'm seeing my friend the landscape architect tonight so I'll try to get a line on that fabric. Hope your project goes well.