Awning groundsheets

Hello

bit of a newbie question here....

we're looking into groundsheets for our awning. most places we shall be using it will be on grass - and at the moment - damp grass....Oh and our awning has the two extra bedroom parts at either end.

I assume breathable groundsheets will let the water up - particularly if its been raining hard. What does everyone use for groundsheets in this situation? PVC non breathable then something over the top??

Found loads of posts about groundsheets on hardstandings, but not on grass.

Thanks in advance!

Matt