There's a cement floor in the back room. Several, actually--almost a patchwork of porches, porches extended, and porches built into rooms.
The people who had the house before us put down carpet padding. Thick carpet padding. Didn't bother to glue it down (thank God). And didn't make sure the back door was actually weather tight (it isn't--there's about a two inch gap at both top and bottom, which means when we get rain with hard wind, we get wet floors inside the door). Which, in turn, meant that the carpet and carpet pad wicked the moisture the length of the room, as well as about a third of the width.
And then it molded.
That was the worst part of today: ripping up that damp, greenish-brown stained carpet, and wet carpet padding. With a dull utility knife. We need to get new blades before we finish the rest.
At least there didn't seem to be any rot anywhere. I suppose there's a major upside to concrete floors.
18 minutes ago