Much delayed, due to general dissatisfaction with my house, and lack of inspiration, I finally feel ready enough to post what I have so far. It took a long time to decide what to use as a base for the house. While at work the other day, I came across good sized sheets of corrugated card, that I felt were sturdy enough to do the job for now.
I am aware how clean the ground looks, and there are no doors or window frames, but really, I am happy enough. I feel that "it will do" until I get the time to make improvements.
With most of the remaining foam board, I finished this ruin too. Not satisfied with just having a stand-alone corner of a building, I based it, and turned it into a full ruin. The rubble is cat litter. I used Crawford and Black acrylic paints for the greys and browns. The lighter shade of grey is an older Revell acrylic, and the inside walls are a colour from a box of paints I bought on ebay. I actually like this more than the completed house.
Now to get inspired for the next building.