If I read it right, Challenger1 may do some lite media blasting after its been steam/pressure washed. I like his method, especially for DIYers because of the fact that its sooooo less messy than trying to clean up all that old undercoating and media from your yard. I am lucky enough to have commercial blasting equipment and lots of outdoor area that I could just run a tractor blade over to level off and leave my mess. Also, when I did mine with cob, I hit it at about a 30 degree angle and mine flaked off in chunks because it was so dry. I'm sure that if my undercoating was still somewhat soft, it may have been a different story.