Service
Radon Mitigation in San Diego County
Permanent radon reduction systems that pull soil gas out from under the foundation and vent it safely above the roofline.
Radon mitigation is the practical work of taking a home that has measured high and bringing it back down to a safe, stable level. It is not a filter, a spray, or a one-time treatment. A mitigation system changes the pressure relationship between the soil under a building and the air inside it, so that soil gas takes the path of least resistance out through a vent pipe instead of up through the slab.
The method used in nearly every successful project is active soil depressurization, usually shortened to ASD. A suction point is cut through the floor slab or sealed into the crawl space membrane, a pipe is routed up through the building or along an exterior wall, and a continuously running fan creates a slight vacuum beneath the foundation. Radon that would have drifted into the living space is captured before it ever gets inside and released above the roof, where it dilutes harmlessly.
Done properly, mitigation is quiet, unobtrusive, and permanent. Done casually, it can be loud, ineffective, or even push moisture and combustion gases around in ways the homeowner never intended. The difference is entirely in the diagnostics performed before a single hole is drilled.
Why this work matters
- Radon is the second leading cause of lung cancer in the United States after smoking, and the leading cause among people who have never smoked.
- Unlike most indoor hazards, radon gives no sensory warning. It has no smell, no color, and no taste, so the only way a household learns it has a problem is by measuring.
- Exposure risk is cumulative. A level that seems mildly elevated becomes meaningful when a family breathes it for a decade in bedrooms and living rooms.
- A properly designed system typically reduces indoor radon by 80 to 99 percent and continues working for the life of the fan with almost no homeowner effort.
Signs this service applies to your building
- A short-term or long-term test result at or above 4.0 pCi/L, the EPA action level.
- A test result between 2.0 and 4.0 pCi/L, where the EPA recommends considering mitigation.
- A real estate transaction where an inspection returned an elevated number and the sale is on hold.
- Visible cracks in a slab, an open sump pit, or an unsealed crawl space with exposed soil.
- A finished basement or converted below-grade room now used as a bedroom or office.
- Recent energy-efficiency work such as new windows or added insulation that tightened the building envelope.
How the process works
- 1
Confirm the measurement
Nothing is installed on the strength of a single ambiguous reading. A confirming test, ideally with a continuous radon monitor placed in the lowest lived-in level under closed-house conditions, establishes both the average and the hourly pattern.
- 2
Diagnose the foundation
The building is walked to identify foundation type, slab thickness, sub-slab material, crawl space areas, plumbing penetrations, and any additions with separate footings. Communication testing measures how far a vacuum travels beneath the floor from a single test hole.
- 3
Design the system
Diagnostics determine the number of suction points, pipe diameter, fan curve, and routing. A house on loose gravel may need one point. A house on tight clay or with three disconnected foundation sections may need several.
- 4
Install and seal
Suction pits are excavated below the slab, pipe is run to the discharge point, and the fan is mounted outside the conditioned envelope. Major slab openings and crawl space membrane seams are sealed so the fan pulls from the soil rather than from indoor air.
- 5
Verify performance
A manometer is mounted on the pipe to show the system is under vacuum, and a post-mitigation test is run after the system has operated for at least 24 hours to document the new indoor level.
Equipment and materials involved
Radon fan
A sealed, continuously running inline fan sized to the airflow and vacuum the soil actually allows.
Schedule 40 PVC pipe
Typically 3 or 4 inch, routed from the suction point to a discharge above the roof edge and away from windows.
U-tube manometer
A simple liquid gauge that lets any homeowner confirm at a glance that the system is pulling.
Polyethylene membrane
Used in crawl spaces to create a sealed plenum over exposed soil.
Polyurethane sealant
Closes slab cracks, control joints, and pipe penetrations that would otherwise short-circuit the vacuum.
Continuous radon monitor
Records hourly readings so before-and-after performance can be documented rather than guessed at.
What you get out of it
- Sustained radon reduction, commonly to well below the EPA action level.
- Lower soil moisture entering the building, which often improves musty odors and humidity.
- A documented, transferable improvement that answers buyer questions during a future sale.
- Low operating cost, generally comparable to running a single light bulb continuously.
- No change to daily routine once the system is running.
San Diego County considerations
San Diego County is not uniformly low risk. The county spans coastal terraces, granitic and metamorphic bedrock in the foothills, decomposed granite soils inland, and fractured formations that can channel soil gas efficiently toward a slab.
Many San Diego homes are slab-on-grade with minimal below-grade space, which changes system design compared with a Midwest basement but does not eliminate the pathway. Sub-slab suction still works well when the pit is properly sized.
The region's mild climate encourages long stretches of open windows, which can mask a radon problem during a casual test. Closed-house testing conditions matter more here than in colder regions.
Homes east of Interstate 15, in the foothill communities, and anywhere built on decomposed granite deserve particular attention when planning a test.
Frequently asked questions
How long does a radon mitigation system take to install?+
Most single-family installations are completed in a single day, generally four to eight hours from arrival to cleanup. Complex homes with multiple foundation sections, long interior pipe runs, or difficult attic routing can extend into a second day. The system begins reducing radon within hours of the fan being energized, though a formal post-mitigation test is not run until at least 24 hours of continuous operation have passed.
Will the system make my house noisy?+
A correctly specified fan produces a soft airflow sound similar to a bathroom exhaust running in another room. Noise complaints almost always trace to an oversized fan, a pipe that is undersized for the airflow, or a fan mounted on a wall shared with a bedroom. Sizing the fan to the vacuum the soil actually produces, and mounting it away from sleeping areas, keeps the system essentially unnoticeable indoors.
Does mitigation lower radon permanently?+
The reduction lasts as long as the system runs and the building stays substantially the same. Fans have a service life measured in years, not decades, so eventual replacement is expected. Renovations that cut new openings in the slab, add a room over unmitigated soil, or change the building's pressure balance can also affect performance. Retesting every two years and after any major remodel keeps the picture current.
Can I install a system myself?+
The plumbing is not the hard part. The diagnostics are. Choosing suction point locations without communication testing, guessing at fan curves, and discharging below a roofline are the three mistakes that produce systems that run continuously without meaningfully lowering radon. A poorly placed system can also depressurize a combustion appliance area, which is a safety concern rather than just an efficiency one.
What level should I expect after mitigation?+
Well-designed systems commonly land below 2.0 pCi/L, and many finish under 1.0 pCi/L. The EPA action level is 4.0 pCi/L, but since no level of radon is considered risk-free, the practical goal is to get as low as the building and soil reasonably allow rather than to stop at the threshold.
Related reading
Related services
Available throughout the county
- Radon Mitigation in San Diego
- Radon Mitigation in La Jolla
- Radon Mitigation in Del Mar
- Radon Mitigation in Carlsbad
- Radon Mitigation in Encinitas
- Radon Mitigation in Poway
- Radon Mitigation in Escondido
- Radon Mitigation in Chula Vista
- Radon Mitigation in El Cajon
- Radon Mitigation in La Mesa
- Radon Mitigation in Santee
- Radon Mitigation in National City
- Radon Mitigation in Coronado
- Radon Mitigation in Imperial Beach
- Radon Mitigation in Pacific Beach
- Radon Mitigation in Mission Valley
- Radon Mitigation in Clairemont
- Radon Mitigation in Mira Mesa
- Radon Mitigation in Rancho Bernardo
- Radon Mitigation in Rancho Peñasquitos
- Radon Mitigation in Carmel Valley
- Radon Mitigation in University City
- Radon Mitigation in Point Loma
- Radon Mitigation in Hillcrest
- Radon Mitigation in North Park
- Radon Mitigation in South Park
- Radon Mitigation in Ocean Beach
Not sure where to start?
Testing is the first step. Send a note describing your home, its foundation type, and any test results you already have.