Use mainly wfp now, but when I use the ladder I put a stopper under it, even in the dry. I once had my ladder slip out from under me on a bone dry, moss free concrete slab so don't take the risk anymore. I was using it yesterday on wet, slimy flagstones and it didn't budge. Also the 18" version fits in to my bucket perfectly when I'm driving, saves water slopping everywhere. One tip with the stopper, I bought some bungee cord, drilled a couple of holes in the stopper and made a handle, makes it a lot easier to carry about.