I've run across several basements recently that have had the typical "interior perimeter waterproofing", with the basement block walls in really poor condition, including peeling paint, cracking parge, and mineral deposit leeching.. This has given me reason to put more thought into the inspection and report coments.
I've always stated that one needs to keep things out of the house rather than trying to correct them once they are inside. That includes, mice, ants, and WATER. Unfortunatly, most people (and waterproofing companies) are more prone to go with jacking up the interior floor slab than excavating the exterior foundation, or even first correcting the exterior grading and drainage, to "keep the water out".
So in these "waterproofed" homes we have these multiple and common remediation actions: 1) vent holes drilled into the top of every block; 2) vent holes drilled into the bottom of every block; 3) a full perimeter wall weepage flap/flange.
Because each of these openings have created more ventilation from the ground to the interior, the volume of sub-surface air and moisture into the home has increased considerably. And what comes along with sub-surface air and moisture is Radon gas.
I could continue on with how the damp basements which have dehumidifiers are drawing even more Radon into the home, but the focus here is simply to point out to the homebuyer or seller why these remediation efforts are dangerous to occupant health. More air flow means the potential for more Radon intrusion.
If you see a basement with one of these repairs, always recommend that a Radon test be performed. A Radon remediation effort in a home with one of these waterproofing systems will be significantly more expensive to solve than a simple "pipe in the ground" installation, as the extraneous air infiltration will need to be corrected FIRST.
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