the best stuff is synthetic foam carpet underlayment. at the top I put a double
layer over the edge. however, people could just trowel on a layer of cement on the
block if they didnt like the looks of a square edge. since this part is not water
holding, I guess I dont worry about it. the shelf was also made of block, and there
I did worry, so 2 layers there but frankly, it doesnt shift and I am not in there
walking on it very often either. Ingrid

"bk" wrote:

I would be concerned about the 90degree edge of the block. I'd think that
this could wear down most cushion materials.