Concrete foundation walls may show rusted foundation ties, honeycombing and are more susceptible to water damage. Parging acts as a barrier protecting the underlying blocks and helps give the foundation a clean consistent appearance since it hides the imperfections in the foundation surface.

Parging is the process of applying thin layers of a Portland waterproof cement mixture on a block foundation wall for weatherproofing purposes. The mixture, consisting of water, sand, Portland waterproof cement and sometimes a liquid concrete weld adhesive, is applied to the foundation wall surface with a trowel. The foundation surface must be clean and dry, meaning that dirt, paint, and foundation tar should be removed from the area prior to applying the cement mixture. Once applied the wall surface must be allowed to dry. However, during the next few days very little water should be used to moisten the cement mixture to assist in its curing process and not allow the cement blocks underneath to suck the water out of the mixture. If the blocks are allowed to do this, the cement layer can weaken and crack.

Possible Complications

The following conditions may cause the parging mixture to not make a lasting bond with the foundation wall:

  • Foundation surface must be clean
  • Foundation surface should be moistened after applying mixture
  • Periodical moistening is suggested for up to a week after application for the curing process to be successful
  • The mixture must be applied in moderate weather, not freezing conditions

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