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How to Beat Moisture on Concrete Block

Answers to pro painters’ most pressing questions 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 at the Sherwin-Williams contractor website

This article was originally published in the Spring 2016 issue of PPC magazine. Rick Watson, director of Product Information and Technical Services at Sherwin-Williams, answers questions from pro painters in the Ask Your ProPartner™ column in PPC magazine.

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