Photo of coated concrete block

How to Beat Moisture on Concrete Block

By Rick Watson

How do I get paint to stick to an old concrete block wall? I thought that masonry paint was supposed to “breathe” to allow moisture to escape. It appears that moisture is pushing the paint off of the concrete – the paint can be peeled off in pieces the size of your fist.

It sounds like you have quite the project ahead of you. Moisture/water in walls can cause paint films to pop off even if they are breathable. Coatings that are breathable will allow water in the form of vapor to pass through. However, when that vapor is in the form of water, it can do damage to the paint film and the structure.

I believe the best way to recommend a system would be to have your local Sherwin-Williams representative look at the project and do a complete free site survey. They will help point out all the steps that need to be taken for a successful project. Here are some things that need to be reviewed and possibly repaired before ever starting to repaint:

  • Roof leaks, drainage and parapet wall issues
  • Wall cap issues
  • Gutter and down spout issues
  • Structural issues/building settling
  • Holes/cracks/pass-throughs
  • Caulk/control joint issues cohesive and adhesive failures
  • Delaminating/spalling concrete/CMU
  • Pinholes and voids in existing paint film
  • Moisture content within wall cavity
  • Adhesion of existing coating to substrate
  • Paint condition

Find more information about concrete coatings.


Rick Watson, Product Information, Sherwin-Williams, answers reader questions in the Ask Your ProPartner™ column of PPC magazine. Read more of Rick’s answers to contractor questions here.

Got a question not answered here? Stop by your local Sherwin-Williams store or contact your sales rep. They are trained to have the product knowledge and application expertise to help you solve your toughest coating problems. Find a store near you

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Rick Watson, Product Information, Sherwin-Williams, writes the Ask Your ProPartner™ column in PPC magazine.