The caulking in my shower was old and had some mold stains, so I removed it and am planning to re-caulk. After removing the old caulking, I noticed that parts of the removed silicon (the ones removed from the space in the picture) were damp and the sand/grout beneath them was damp. This even though I had not used this shower in about 3 weeks.
I am planning to spray some mold killer in the spaces before resealing. My concern is that the gap is a little big (maybe 3/8 inch), and if I apply silicon directly, water may seep through again over time. Would it be better to put something in the gap first, before applying silicone? Also, how worried should I be about the slight dampness in the gaps?
Thank you very much