This is the largest Casa I designed and built. When finished the outside section was 6 long 5 high and 3 deep. It had two floors; one that could hold up to 6 large litter boxes, with the second floor designed for the play and resting area.
The inside section that fit in the window was 4 high 2 wide and 18 deep. I also installed solar lighting, 110 volt power for cleaning, plus four venting fans. The customer owned up to 20 cats at a time and this Casa was the perfect answer for her litter box odor problems.