I have a small room under the stairs that we use for storage. It's also the entrance to the crawl space. The wall straight in is concrete and the PO glued white foam on for insulation. The floor is a vapor barrier, about 4-6" sand, then a wood deck on top. The room smells very musty and if we were to store fabric/sleeping bags, etc, they pick up the smell. This second picture shows where I cut out some drywall. There is no concrete below that wall, they framed down, drywalled and backfilled sand against the drywall, causing some mold. So, was hoping to use our tax return to try to fix this room but not totally sure what to do... here's what I'm thinking (with questions in different color).. - remove sand and pour a concrete floor. Form a new base for the wall that is currently missing it. How much sand to remove, right down to vapor barrier? Do I leave the vapor barrier there? How thick do I need to pour the floor? - remove foam insulation, replace with 2" polystrene - remove old drywall, replace any moldy insulation. Replace, tape and paint. Can anyone add anything I might be missing or don't really need to do? Thanks for any replies, much appreciated!