My buns house is also on concrete because it’s in my basement. I have the foam puzzle pieces down first, then an indoor outdoor carpet with some texture to it. Over the carpet I put down a fleece blanket and then I put the house on top of it so the edges stick out and he can’t eat them or dig them up.
The puzzle pieces were $10 and I had some left over I use to block areas off in my room. The indoor outdoor carpet I got at lowes for $20 and I cut it down to the size I needed with plenty left over if I expand or need it for somewhere else. I bought his fleece at walmatt, the larger stores have a fabric section and you can buy fleece by the yard for like $3 a yard. In the winter also keep an eye out for the fleece blankets they’re like $2.
I wash his fleece with all the other blankets and towels I use for him once a week. And I can spray his carpet with vinegar, rinse with water and air dry. Foam puzzle pieces I just wipe down with vinegar. It sounds like a lot but it only takes me about 30 minutes to do his full cage clean once a week. During the week I just clean litter boxes every other day and scoop up any excess hay and poops that made their way out of his litter box.