Baseline Data for Indoor Air Safety
Radon testing in McHenry for residential and commercial properties during real estate transactions or long-term occupancy planning
Radon is a colorless, odorless gas produced by the natural decay of uranium in soil, and it enters buildings through cracks in foundation slabs, gaps around pipes, and sump pump openings where soil gas moves into conditioned spaces. Northern Illinois sits in EPA Zone 1, where elevated radon levels are common, and the only way to know whether your property has a problem is to test—you can't see it, smell it, or predict levels based on neighboring properties. G.R. General Contracting provides radon testing in McHenry using continuous monitors or passive canisters that measure concentrations over a set period, giving you accurate data to decide whether mitigation is needed.
Testing involves placing monitors in the lowest occupied level of the building, keeping windows and doors closed during the test period to reflect normal living conditions, and recording radon concentrations in picocuries per liter. The EPA action level is 4.0 pCi/L, and results above that threshold indicate mitigation should be considered to reduce long-term exposure risk.
Schedule a radon test during real estate inspections or anytime you want baseline data on indoor air quality for your property.
What Radon Testing Actually Accomplishes
Radon testing measures airborne concentrations using devices that either passively collect samples over several days or actively monitor levels continuously with real-time data logging. Short-term tests run 48 to 96 hours and provide a snapshot of current conditions, while long-term tests cover 90 days or more and account for seasonal variations in soil gas movement. Results come back as a numerical concentration, and anything at or above 4.0 pCi/L suggests mitigation should be discussed with a qualified contractor.
Once testing finishes, you have documented radon levels for the property, which informs decisions about whether to install a mitigation system, re-test seasonally, or proceed with a real estate transaction based on known conditions. Testing doesn't change radon levels, but it gives you the information needed to address exposure risk, especially in homes where basements or lower levels are used as living spaces.
Testing frequency depends on the situation—real estate transactions almost always include radon tests as part of the inspection process, and homeowners in high-radon areas may re-test every few years or after foundation work that could affect soil gas entry. Mitigation systems typically lower concentrations below 2.0 pCi/L, and post-mitigation testing confirms the system is working as intended.
Questions Before Starting Your Project
Property owners in McHenry arranging radon testing often ask about the process, timing, and what results mean for their building or transaction timeline.
How long does radon testing take?
Short-term tests run two to four days with results available within a week, while long-term tests cover three months and provide more accurate seasonal averages—real estate transactions typically use short-term tests to meet closing deadlines.
Where should radon monitors be placed?
Monitors go in the lowest occupied level, away from exterior walls, windows, and doors, and they should sit at least 20 inches off the floor to avoid ground-level disturbances—basements and first-floor rooms above crawl spaces are common test locations.
What do radon test results mean for health risk?
The EPA recommends mitigation at 4.0 pCi/L or higher because long-term exposure at those levels increases lung cancer risk, and the higher the concentration, the more urgently mitigation should be considered.
Can radon levels change over time?
Seasonal soil moisture, barometric pressure, and ventilation patterns all affect how much radon enters a building, which is why long-term tests provide more reliable data than short-term snapshots—levels can vary between winter and summer.
What happens if test results come back high?
Results above 4.0 pCi/L indicate a mitigation system should be installed to vent soil gas before it enters the building, and re-testing after mitigation confirms the system is reducing concentrations effectively.
G.R. General Contracting conducts radon testing for properties throughout McHenry, providing clear results and recommendations based on measured concentrations. Arrange testing during your inspection period or anytime you want to assess indoor air quality for long-term occupancy planning.