I have five litter boxes for 2 cats. I have 4 out on a screened in porch - and keep them there all year round. And I have one inside, in a closet. My two monkey cats use all 5. Some are small, one is covered, 4 with one kind of litter (World' Greatest) and 1 with Costco clumpling letter, which they prefer. I have a huge porch so it is not a problem. So far, there have been no accidents. There was a problem when I first brought them home though, when the male kitty (Graemer) would go behind the refrigerator and pee. I discovered it when it came running out from under the fridge one morning. I was horrified and then put out lots of litter boxes. I washed the area with lemon scent stuff and he never went back. I don't think his urine was very strong then, and I couldn't smell it.

I would get one more litter box and make it big! He may prefer to do his business in two different boxes.

Last resort would be a trip to the Vet to see if something is going on in his stool. Sometimes cats have this uncanny way of letting you know that there is a problem.

Good luck. Let us know how it turns out!