Reading the most recent Hollander magazine reminded me of a rabbitry housekeeping tip that I didn't see mentioned. After we had the concrete slab floor poured, we put a concrete sealer over it. This can be applied with a roller or brush.
The sealer helps prevent urine, dirt and water from penetrating the concrete. No urine penetrating the concrete helps keep odors down. The sealer also helps prevent flaking of the concrete surface.
We were fortunate enough to apply it on a new floor. It is possible to apply a sealer on an old floor or at a later time. To do so, empty the room and thoroughly clean the floor. Allow 24-48 hours to dry or follow the instructions on the gallon or five gallon can. So plan on this taking a few days of keeping the bunnies elsewhere.
We have a drain in the center of the rabbitry so when hosing the floor clean takes care of any standing water. You try not to have a lot of moisture in the air. We first sweep any shavings or stray hay off the floor before hosing it clean. You can wet the floor and pour some bleach or vinegar in different areas. During extended humid days we may hose the floor and this drops the indoor temperature down. Overall, the rabbitry is much cooler in the summer than outdoors in part due to having a concrete floor.
Just be careful that if there are wet spots or if the floor is sweating that you don't fall as it can become quite slippery.