My dogloo sits right on the ground. I use the deep litter method so in reality its about 6-8 inches of the ground now and was about a foot off the ground at the end of winter. I kept the door open and the vent open at the top of the dogloo all winter even when it meant cleaning snow and ice away from it.
The wooden dog shed has legs that elevate it about 3 inches off the ground. It was on the deep litter bed, too, so there were no drafts coming underneath it. This is a prefab dog shed so the boards fit together tightly--no visible spaces.
I checked the nesting material daily but really i only needed to change it only a few times over the winter. Before they went broody they were really really good about not pooping in the nest/ structure that was used for the nest. My main layer hen picked which building she was going to lay in and that's the one they all used for laying that day.
I was using straw inside the houses and kept about 2-3 inches, maybe more, in each. I just switched over to shavings because one of my hens got a bumble from a wild rose thorn. I was worried that the stemmy straw i have access to might hurt her feet. I haven't made up my mind about the shavings yet. The ducks dont really seem to have a preference but they don't seem as cushy as the chopped straw to me.
Im gradually switching over to corn cob bedding. It has amazing water absorbing power and it is super soft. I don't know how well it will work over winter or how much I'll need to keep in there for the winter. I'll probably keep chopped straw or actual feeding hay on hand to top dress the bedding during snows.