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Context
A buyer under contract to purchase a 1968-construction Squirrel Hill home with a partially-finished basement retained us for pre-closing radon testing. Allegheny County is EPA Radon Zone 1. Average indoor radon levels are higher than the national average, and pre-1980 construction typically lacks sub-slab depressurization or vapor barriers. The seller had provided a free Allegheny County Health Department charcoal-canister kit result of 4.8 pCi/L; the FHA lender required a continuous radon monitor (CRM) report for the closing file.
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Methodology
EPA short-term protocol: closed-house conditions established 12 hours prior to monitor placement; continuous radon monitor (Sun Nuclear 1028) deployed in the basement living area at 36 inches off the floor and 8 feet from interior walls; 48-hour measurement period with hourly readings recorded. Instrument was calibrated by the manufacturer within the prior 90 days per PA DEP requirements.
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Initial reading
Final 48-hour average: 12.4 pCi/L. Hourly readings ranged from 8.2 to 18.6 pCi/L, with elevated readings during overnight hours consistent with reduced ventilation. This significantly exceeded the EPA action threshold of 4.0 pCi/L and required mitigation before closing under the FHA lender's environmental requirements.
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Mitigation design referral
Because we do not perform radon mitigation, we referred the buyer to two independent PA-DEP-certified mitigators for competitive bids. The selected contractor installed an active sub-slab depressurization (ASD) system: PVC pipe through the basement slab to outside-discharge above roof line, in-line radon fan (Radon-Away RP-265) sized for the home's footprint, manometer pressure gauge for visual monitoring. Install cost: $1,485.
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Post-mitigation verification
We returned 4 weeks post-install for follow-up CRM testing under closed-house conditions. Final 48-hour average: 1.9 pCi/L. Below the EPA action threshold and below the 2.0 pCi/L EPA-recommended consideration threshold. The FHA lender accepted the post-mitigation report and the closing proceeded.
