Yes. Any foundation work, sump pit modification, or significant air-sealing changes the radon equilibrium. Retest within 30-90 days of completion. The free post-mitigation 12-month retest is included on every credentialed install.
More detail
Foundation work that changes radon dynamics: basement waterproofing (interior or exterior), sump-pit installation or replacement, slab repair or partial replacement, basement finish work that adds a vapor barrier or significant new sealing, and rim-joist insulation that closes off previously-open air paths. Each of these changes the home's air-pressure profile and can shift radon levels in either direction. Retest 30-90 days after the work completes; same-week testing reads erratically as the home reaches a new steady state. If a mitigation system is already installed, retest with the system running normally; the work may have changed the suction pattern enough to require fan adjustment. Your installer will return for a free retest of any system they originally installed; for systems installed elsewhere, the retest is a fee-for-service line item. Cincinnati post-renovation timing: 30-90 days after the work completes is the right window. Same-week post-renovation testing reads erratically as the home reaches a new air-pressure equilibrium. If a mitigation system was already installed, retest with the system running normally and at its original settings; the work may have changed the suction pattern enough to require fan adjustment, which is handled as a no-charge follow-up within the workmanship warranty window.