We started off with the spongey green mesh but in wet conditions it did tend to soak it up and stayed wet for a while. We now have Isabella Bolon grey plastic breathable groundsheet instead, it's not cheap but it is hard wearing, should last for ages and doesn't soak up moisture.
Dave
------------- Give a man a fish and he will eat for a day,
Teach a man to fish and you can get rid of him for a whole weekend.
Moroccan Mats...interwoven plastic. Air permeable and strong. We bought ours at a show, and many sizes are available. Had ours for years now. (2209) So hardwearing also. Only thing is they are difficult to fold down to a small size.