SO I need to drylok my basement. Pretty straight forward... 4 walls/ block. The old drylok is literally falling off, and underneath is paint which could date back to the year my house was built. I was told I need to wash the walls inorder to get that original paint off the wall. I was told this would have to be done with a nasty chemical wash (this coming from a Home Depot rep). Do I really need to wash the walls? I think scraping the walls (wire brush and orbital sander combo) will rough up the surface of the block enough that new dryloc will stick. And yes, I've already gotten into a fight over this project. AS a Female home owner, I think I was told a line of crap from the Home Depot guy. Any suggestions?