I'm about to start painting my basement walls with drylok. Previous owner waterproofed.....stuff looks to be about 10-15 years old. Has some stain marks in areas which shows there has been some water in the past. Was going to uses a wire brush and scrapper to get the old drylok off, use some water stop cement on the cracks that I find, and then drylok over everything.

Any easy way to get the old drylok off? Should I just clear the areas where there is staining. Basement has no leaking, and the walls are cinder blocks

  • 1
    Why would you want to remove a well-bonded layer of the same thing you're applying?
    – isherwood
    Apr 19, 2016 at 17:27
  • What's your goal here? If you just want a fresh coat and the existing waterproofing is working well, you can apply latex paint over drylok. If you need to patch areas first, hydraulic cement and new drylok makes sense. As @isherwood said, there's no point to removing well-bonded areas of existing waterproofer. Apr 19, 2016 at 18:03
  • Believe me...I do not want to. Can I just scrap the loose stuff, and then repaint? There are spots where there are water stains. Wasn't sure If I had to remove all the old stuff....or could just paint over
    – Scott
    Apr 21, 2016 at 23:13

4 Answers 4


You might want to consider speaking with drylok representitives to find out how to remove the product safely. It contains Silica which is extremely toxic in dust form. The products has warnings regarding it on the label. I'm considering using it on my basement fieldstone and my only reservtion is the possibilty of having to remove it if it fails. Or having someone else get sick trying to remove it in the future. I'm sure it's inert when its on the wall, just not so sure about any dust/debri created from sanding or grinding or chipping. Good Luck.

  • Hello, and welcome to Stack Exchange. Good answer; hope to see more from you. May 14, 2018 at 12:36

Frankly there's no easy way. A few options can be had with a bit of elbow grease. First is your proposed plan. Second is attach a diamond grinding wheel to a variable speed angle grinder and use a fan for ventilation. This will generate lots of dust. Third is to simply scrape off the loose paint and recoat with drylok after washing the staining off with a mold removal cleaner. I'm assuming the staining is black mold.

  • 1
    Sandblasting, perhaps...
    – keshlam
    Apr 19, 2016 at 3:33

Water problem corrected from exterior. Needed to remove 140 sq. ft (7'x 20') of mostly mint condition Drylok from the only painted section of my basement cinder block wall. Unbelievably difficult. I found no solvent on line that said it could take it off (though I saw a post for Peel away 7 afterwards). I ended up renting a 200 degree hot, high pressure power washer with 50" hose to reach my wall and blasted the top layers off. Unfortunately it filled my house with steam that took 3 days to dry out and odor to disappear. Industrial fan used to dry soaking wet basement. I then used my regular power washer and the strongest industrial paint remover I could find, using a tight spray beam one inch off wall, alternating paint remover application and power wash (6 times in total). Industrial fan used to vent basement while working and shop vac for water removal. Took 4 days (7-8 hours/day). Walls look pristine as if Drylok never applied.


Dry-lock is only guaranteed to waterproof over bare cinderblock,so you have to remove ALL the old sealer. If you just remove the old peeling waterproofing, you can patch if necessary with Fast Plug or Hydraulic Cement and then put two coats of Drylock over these areas to guarantee it will be waterproofed. If the old areas that have waterproofing that is sticking but leaking water, you have to remove it and apply Drylock over the bare surface in order to guarantee water will not come through.

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