We have some guests due in late march and the floor of our utility room was looking nasty and saggy, so I went on a little exploration and found the whole thing to be a mass of rot. I had put in some glass wool insulation under it and that had all been hustled hither and thither by a number of inhabitants. It was all matted down by the damp that must have been present at some time. It took half a day to get all the horrible stuff out and I had time to put in a couple of pieces of the new floor underlay before it was time for everyone to use the bath.
I rebated the new timbers to lay polystyrene into the spaces between joists, on the kitchen floor I had used laths tacked onto the joists, but it seemed about the same amount of work to do the rebates. To help protect the undersides of the styrofoam I laid in some of the plastic board I had left over from cladding the dome. I can't get in under there, but it must look dauntingly neat to any stray rodent that happens to find its way in. The second day on the job is on the left as I get ready to lay one sheet of subfloor (spruce plywood) in so that the bathroom will be accessible for bath time.
I had just enough of the pine flooring planks I used in the kitchen left over to do this small space and I think the freezer, washing machine and the rest were all back in place by the end of the fourth day. I boiled up the persimmon tannin and charcoal ink mix I painted onto the kitchen floor and that seemed to loosen up ok. The persimmon part seems to bind up into lumps when left to stand too long. It seems to mature into a slightly warm grey color over time.