Home › Mitigation › Sub-Slab Depressurization

Sub-Slab Depressurization in Toledo, OH

Sub-slab depressurization (ASD) is the standard radon mitigation method for homes with a basement or slab-on-grade foundation. A continuous fan creates negative pressure beneath the slab so soil gas is drawn out and vented to outdoor air rather than entering the home through cracks, the slab-wall joint, or sump openings.

When ASD is the right system

• Poured concrete or block-wall basements with a finished or unfinished slab.
• Slab-on-grade ranches and additions common across Lucas County.
• Walkout basements where one slab section is below grade.
• Homes with a single sump and a reasonably intact slab.

Suction-point placement

One suction point per ~2,000 square feet of slab is the rule of thumb in this region. Placement avoids load-bearing walls, plumbing runs, and post-tension cables. For homes with multiple slab sections separated by footings, two or three suction points may be tied into a single 4-inch riser.

Fan sizing

Most Toledo-area homes need a 90- to 180-watt inline fan in the static-pressure range of 1.0 to 1.6 inches w.c. Tighter slabs and homes built on Maumee shale may need higher-pressure fans; loose gravel sub-bases tolerate lower-watt models. Final fan choice is set after a diagnostic measurement on the day of install.

Performance

Properly designed ASD reduces indoor radon by 85 to 99 percent. Pre-mitigation levels of 8 to 12 pCi/L typically end up under 1.0 pCi/L after install. Post-mitigation testing confirms the result.