There are sort of 2 different issues w/covering the pens: hawks, and raccoons. Hawks will be kept out by the twine-type netting you mention, or a lot of people here feel they are pretty successful just by stringing twine back and forth and back and forth above the enclosure (with or without CDs on the twine).
Raccoons however will just climb your fence and go straight thru that sort of thing and have chicken for dinner
So, what are your raccoonproofing plans?
As far as the pen floors, is it possible to just trench around the problem pen so the water does not flow *thru* it?
Good luck,
Pat
Raccoons however will just climb your fence and go straight thru that sort of thing and have chicken for dinner

As far as the pen floors, is it possible to just trench around the problem pen so the water does not flow *thru* it?
Good luck,
Pat