We recently purchased a house and are in the process of moving into it. The house we bought has a very nice lower level storage room and is below ground level. It's quite large and has no windows. It houses two water heaters, a furnace, and a central whole house vacuum system. It has two interior doors to it. They are not solid core doors. I'd like to make the room as secure as possible. Maybe buy two solid wood doors, or put some steel plate on the existing doors? Or.....maybe some heavy gauge sheet metal? Anyone on here have any experience fortifying interior doors? Anyone have any suggestions, tips, and/or advice? I'd like to do this sooner than later. But.....I'm not in a real big rush. Just wanna get it done before the year is up if possible.