Isn't there the risk of something digging under and getting the ducks?
If I build a coop should I consider a hardware cloth floor?
Yes there is always that risk but I haven't had any predators here yet. I had a raccoon try to get into that chicken coop last summer but it soon gave up and never returned. It's like as soon as we secured out garbage and placed paver bricks around the coop they left and never came back. I would do the same with the duck coop, placing pavers around the outside edges.