We started renting our current house in mid-2013. The upstairs is the living space and the downstairs is my workshop space. The floor areas in theory are the same size (great), but the underneath has large areas that have not been fully dug out and concreted (not so great), so it makes the space more difficult to use. This (poor quality) picture was taken before we moved in. The unfinished area in the foreground is the area I want to make usable.
Either digging out this area and concreting it, or building a permanent raised subfloor over this area would both be possibilities if the space were ours to modify. In my case, I want something strong and stable, and to maximise use of that area, but it has to be a temporary fixture, without fixing anything into the building or floor. I came up with this system shown in the picture. Several very large pieces of dowelling are glued and screwed into a rear support beam for the platform. The beam just sits on the wall, and the dowelling sits inside the holes of the bricks. With it set up this way, the platform can’t be pulled away from the wall, and can’t be pushed left or right.
With the front beam in place, and a pair of legs, it doesn’t move. At this point I was pleased. I wasn’t sure whether my plan would work or not, but it has worked better than expected. So far I’ve just used scrap wood, but now it’s worth spending money on some plywood for the top.