I have a 12 year old cat, who has been peeing/pooping in our basement. She has done this before a while ago, but stopped the habit after changing her litter. Then, this past summer, we took down our shed and much of it's contents are currently in our garage where her litter box is. Soon after, she started refusing to use the litter box. My mother got tired of cleaning up after her and put her outside for the summer. (She is an indoor/outdoor cat.)
We've recently let her back in due to the cold weather (after 4-5 months I'd say) and us being out of town for Thanksgiving. It was easier to get someone to feed her that way if she's in the house.
At first she seemed fine and had no issue. We were more careful to clean her litter box more often. And coming back from Thanksgiving, we found pee/poo in the house again.
We don't want the litter box in the house, because she is usually messy with it and there really isn't any convenient space in the house for it. I don't think it's a urinary infection, because she hadn't gotten back into the habit until we tore down the shed. We aren't going to get her checked out, because it's expensive and we are pretty positive it's the stuff in the garage.
I am just not sure what to do anymore to correct this. She'll get put in the garage for the winter if she doesn't stop this act. I think come this next summer we'll put up a new shed, but until then I'm not sure what I can do. But if this keeps up, she'll be kicked out of the house again.