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Crawlspace Radon Mitigation in Toledo

Older Toledo homes and rural Lucas County properties often have a dirt, gravel, or partial crawlspace rather than a poured basement. Radon enters those homes directly through the soil floor at a much higher rate than through a slab. Mitigation in those cases is encapsulation plus sub-membrane depressurization.

The encapsulation process

1. Debris removal and grading. The soil floor is cleared and graded so the membrane lies flat without trapping water.
2. Vapor barrier. 12- or 20-mil reinforced polyethylene is laid across the entire floor with overlapping seams.
3. Perimeter seal. The membrane is mechanically fastened up the foundation walls and sealed with butyl tape and termination strips.
4. Sub-membrane depressurization. A perforated PVC pipe is tied beneath the membrane and routed up to a fan that vents above the roofline. The fan pulls soil gas out from under the barrier continuously.
5. Vent sealing. Foundation vents are sealed and the crawlspace is converted to a conditioned (or semi-conditioned) space.

Why vented crawlspaces fail

Open foundation vents do not measurably reduce radon. Air movement through a vented crawlspace is too low and too directional to dilute soil gas, and in winter the stack effect actively pulls radon up into the home. Encapsulation with active depressurization is the only method that consistently brings crawlspace homes below 4.0 pCi/L.

Side benefits

An encapsulated crawlspace also reduces ground-moisture intrusion, slows wood-rot in the band joist, and cuts musty odors that travel up into the living space. None of those are the primary reason for the install, but they are the reason most homeowners describe the project as worth the cost.