Radon Mitigation System Installation

What the problem is

Radon is a colorless, odorless radioactive gas produced as uranium in soil and rock breaks down. It moves through soil and enters a house through the path of least resistance: slab cracks, the gap where the slab meets the foundation wall, plumbing and utility penetrations, sump pits, and open crawlspace soil. Because a heated house is slightly depressurized compared to the ground beneath it, the building itself pulls soil gas inward.

Radon exposure is the second leading cause of lung cancer in the United States after smoking. Unlike most indoor air issues, you cannot smell it, see it, or feel it, and there is no short-term symptom to react to. The only way to know a home's level is to measure it, and the only way to lower it reliably is to change how soil gas moves under and into the building.

How to know if you have it

• A short-term or long-term test came back at or above 4.0 pCi/L, the EPA action level.
• A test came back between 2.0 and 4.0 pCi/L — the EPA suggests considering mitigation in this range.
• A real estate inspection test triggered a repair request during a sale.
• A neighbor tested high. Radon varies house to house, but shared geology raises the odds.
• The home has a basement, a crawlspace, or a slab with visible cracks and untreated penetrations.

If you have not tested yet, start there. Mitigation without a measured starting number leaves you no way to prove the system worked.

How the home is diagnosed

A mitigation system is not one-size-fits-all. Before anything is installed, the home is walked and measured so the design matches the actual foundation:

1. 1Foundation review: slab-on-grade, basement, crawlspace, or a mix of all three in an addition.
2. 2Sub-slab communication test — a small test hole is drilled and suction is applied to measure how far vacuum travels under the slab. This determines how many suction points the house needs.
3. 3Aggregate check: clean gravel under a slab moves air easily; compacted native soil or caliche does not, and needs more suction points or a higher-capacity fan.
4. 4Entry-point survey: cracks, cold joints, sump pits, plumbing chases, and crawlspace soil are noted for sealing.
5. 5Routing review: where the pipe can run, where the fan can be mounted, and where the exhaust can terminate above the roofline and away from windows.

What the installation process looks like

1. 1A suction point is cut through the slab and a cavity is excavated beneath it so the fan can draw from a broad area.
2. 2Sealed PVC pipe is run from the suction point to the fan location — typically through the garage, an interior chase, or up an exterior wall.
3. 3An inline radon fan is installed outside conditioned space (attic, garage attic, or exterior wall) so any leak in the pressurized side of the pipe cannot discharge into the house.
4. 4The exhaust terminates above the roof eave, at least 10 feet from any window, door, or air intake.
5. 5Slab cracks, the floor-wall joint, sump lids, and utility penetrations are sealed so the fan pulls soil gas rather than conditioned indoor air.
6. 6A manometer (U-tube pressure gauge) is mounted on the pipe so you can confirm at a glance that the system is running.
7. 7Electrical is connected to a dedicated switch or circuit, and the system is labeled per protocol.

Expected timeline

What affects the cost

• Number of suction points required — driven by the communication test, not by square footage alone.
• Foundation type and whether a crawlspace needs a vapor barrier.
• Interior routing (more finished work, cleaner appearance) versus exterior routing.
• Fan sizing — tight soils need a higher-static-pressure fan.
• Electrical work if no circuit is available near the fan location.
• Slab sealing scope and access difficulty.

What happens after installation

Installation is only half the job. A system is not finished until a post-mitigation test proves the level dropped. Testing begins after the system has run continuously for at least 24 hours and follows the same closed-house protocol as the original test. The result should be well under 4.0 pCi/L, and in most homes under 2.0 pCi/L.

• Check the manometer monthly — if the two liquid columns are level, the fan has stopped.
• Retest every two years, and after any major renovation, foundation work, or fan replacement.
• Radon fans typically run continuously and are designed for it; plan on replacement somewhere in the range of 8–12 years.
• Keep the system running year-round. Turning it off in mild weather defeats it.