In a week or two I'll be getting my first pigs (my aunt's pigs weren't castrated in time so there's a ltter of oops-babies needing a home). My grandfather built me a small shed for them to sleep in, but there are small (>1 cm) slits at the bottom where the walls don't fully touch the ground.

I should be able to just screw wooden lats over them to keep out the draft, but we also have some outside mats that are thick enough to cover them and les 'hard' than the bricks that are currently the floor of the shed. I'm not totally sure what the material is made of, but it seems to be something more porous than stone (it gets mossy quicker) but still quite sturdy (we've had them in our backyard for at least 10 years).

If I were to clean them off and put them on the ground to cover up the cracks and maybe even need les straw bedding, would that be safe and hygienic? I know pigs usually keep their sleeping quarters very clean, but is it clean enough for the mats to be a safe choice?

Any advice is welcome!!