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If radon is entering our homes through cracks and other openings in the foundation, can we solve a radon issue by sealing all the openings? In theory, the answer is yes. However, in existing buildings sealing all the openings may not be practical or technically feasible. Take for example a finished basement where the foundation walls and floor may not be readily accessible.

Even where we think we can identify all the possible openings, Health Canada has published an estimate of the level of sealing that would be required to solve a radon issue, and it is not encouraging. Leaving total openings of 1 cm^2 (or more) will render the sealing effort ineffective (Health Canada, 2010). That’s about the area of a finger nail.

This is not to say that sealing openings is not important. The effectiveness of active sub-slab depressurization techniques can be improved by sealing major entry routes. Our experience has indicated that careful sealing efforts at the time of construction can also be effective. Sealing is important, but may not serve as a standalone radon solution.

Health Canada, 2010. Reducing Radon Levels in Existing Homes: A Canadian Guide for Professional Contractors.

A shrinkage crack, before (left) and after (right) grinding and sealing.


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