Sorry if I'm a little late to this thread and your situation. However, as someone who lives in Colorado, where there are pretty large snakes, keeps their guinea pigs in the basement, has a huge cage, and keeps their piggies indoors, I’m glad I got mentioned. I've got a pretty similar situation.
I'm a person who would just pick a snake up if I saw one (
), I haven’t really put any thought into this until now, since it’s not really one of my priorities, but here are some things that I have thought of. It definitely makes sense though and I agree with making their cage area safer and more snake-proof.
If your guinea pigs live indoors, then I doubt a snake would make it into your house without you knowing(obviously could happen though). Definitely keep the door to the basement closed but you could install a door sweep or even weather stripping if it's not the sliding type door.
If there are any gaps in the foundation, door, or windows seal them up also.
Maybe some mesh over vents or drains? Snakes can get into pencil-sized holes. I’m nowhere near sure if those types of snakes have rodents in their appetite though.
You could also elevate the cages with a table or purchase some C&C grids to make a base with.
I agree with you as well on the snake repellent. It could be harmful to the piggies.
You seem to care very much about your piggies so I hope some of that helps. Let us know how it goes with moving them upstairs if that’s the final plan.
I will note that a stacked cage is harder to clean.
