Does the radon mitigation system run all the time?

Yes — the fan runs continuously, 24/7. The moment the fan stops, radon begins accumulating again. Fans are designed for continuous operation and use 25–90 watts, typically adding under $10/month to your electric bill.

Will the system lower radon levels immediately?

Levels begin dropping immediately but wait 24–48 hours before testing. Keep windows closed (normal closed-house conditions) for accurate post-installation test results.

How Radon Mitigation Works

A plain-language breakdown of sub-slab depressurization — the gold standard method for reducing radon in Maine homes — from assessment to final test.

The Short Answer

Radon mitigation works by reversing the air pressure relationship between your home and the soil beneath it. Radon gas enters homes because the air pressure inside is slightly lower than the pressure in the soil — so gas flows in through cracks, gaps, and porous concrete. A mitigation system creates a dedicated low-pressure zone beneath your slab and vents that gas safely outside before it can enter your living space.

The technical name for this is sub-slab depressurization (SSD). It's the method recommended by the EPA and used by NRPP-certified mitigators throughout Maine. When properly installed, it typically reduces radon levels by 80–99%.

Why Maine Homes Are Particularly At Risk

Maine's geology is dominated by granite and related metamorphic rock — both naturally high in uranium, which decays into radium, which decays into radon gas. As that gas forms in the rock and soil, it follows the path of least resistance: upward through soil pores and into the lowest pressure zone it can find. In winter especially, heated homes pull air from below — and radon comes with it.

EPA Radon Zone 1 (the highest risk category) covers much of inland and central Maine. Even Zone 2 counties like Knox and Hancock regularly produce homes with radon well above the 4 pCi/L action level.

The Installation Process, Step by Step

Most Maine home installations are completed in a single day. Here's exactly what happens.

Pre-Installation Assessment

Before drilling, we assess your foundation type and basement conditions. We're looking for the lowest-pressure point beneath your slab — typically near a sump pit, floor drain, or a location with the thinnest concrete. We also check for any conditions that could affect airflow beneath the slab, such as gravel fill, clay, or solid bedrock.

This step determines how many suction points your home needs and where to route the pipe. Most single-family homes require one suction point. Complex foundations with multiple isolated sections may need two or more.

Drilling the Suction Point

We core-drill a 4-inch hole through your basement slab at the chosen location. Beneath the concrete, we excavate a small void in the sub-slab material to create a collection chamber. This is where the negative pressure field will form — drawing radon gas from the surrounding soil before it can enter your home.

We verify airflow communication across the sub-slab area by testing pressure at the suction point. If the airflow is insufficient (which can happen in homes built on bedrock), we may add a second suction point.

Pipe Routing

We install a 4-inch PVC pipe from the suction point, routing it through the basement and up through the house — or around the exterior — to a point above the roofline. The pipe is the exhaust pathway: radon gas travels from below your slab, up through the pipe, and out above the roof where it dissipates safely into the atmosphere.

We take care to route the pipe as neatly as possible, keeping it along joists, inside closets, or along exterior walls where it's least visible. The goal is a professional-looking installation, not just a functional one.

Fan Installation

We install a continuously-running radon fan in the pipe — typically in the basement, attic, or garage, or on the exterior in a weatherproof housing. The fan creates and maintains the negative pressure beneath your slab. It runs 24/7 on very little electricity — typically drawing 25–90 watts, similar to a light bulb.

We select fan size based on the sub-slab conditions measured during assessment. Homes with high sub-slab resistance (tighter soil, more suction points needed) require a higher-capacity fan than homes with good gravel fill beneath the slab.

Manometer Installation & System Verification

We install a U-tube manometer — a simple liquid-filled indicator — on the pipe where it's easily visible. The fluid level shows at a glance whether the system is maintaining negative pressure. If the levels are equal, the fan isn't working. If one side is lower, the system is operating correctly.

We measure the pressure differential and compare it to target values, verify all pipe connections are sealed, and walk you through how to read the manometer and what to do if it ever changes.

Post-Installation Testing

We strongly recommend retesting your home with a radon test kit 24–48 hours after installation. A properly functioning system will typically reduce radon levels to below 2 pCi/L — well under the EPA action level of 4 pCi/L. We do not perform radon testing ourselves, but we can point you to certified testers in your area or recommend a charcoal canister kit.

We provide a written completion report documenting the system components, installation date, and our contractor certification — suitable for real estate disclosures or your own records.

Mitigation System Types

Sub-slab depressurization is the most common approach, but your foundation type determines the exact method used.

Sub-Slab Depressurization (SSD)

Most Common — Poured Concrete & Block Foundations

The standard approach for homes with a poured concrete or concrete block basement slab. A suction point is drilled through the slab, and a fan draws radon from beneath it. Effective for the vast majority of Maine homes.

Drain Tile Depressurization

Homes With Interior Drainage Systems

When a home has a perimeter drain tile system (common in newer construction), the fan can connect directly to the drain tile loop rather than requiring a slab penetration. Often more effective than standard SSD because the drain tile communicates across the entire perimeter.

Crawlspace Encapsulation

Homes With Crawlspace Foundations

For crawlspace foundations, we install a heavy-duty vapor barrier across the crawlspace floor and walls, then use a fan to depressurize beneath the barrier. This approach also reduces moisture and improves air quality — two common crawlspace problems in Maine's climate.

Common Questions About How Mitigation Works

Does the mitigation system run all the time?

Yes — the fan runs continuously, 24/7. This is intentional. The moment the fan stops, the pressure differential disappears and radon gas begins accumulating beneath your slab again. The fans are designed for continuous operation and are very energy-efficient, typically using 25–90 watts. Most homeowners see less than $10/month added to their electric bill.

Will the system lower my radon levels immediately?

Radon levels begin dropping as soon as the fan turns on, but it takes some time for the gas already in your home's air to dissipate. Open a window for ventilation in the first few hours after installation. For accurate post-installation testing, wait at least 24–48 hours and keep windows closed (normal closed-house conditions) before placing a test kit.

What happens if my radon level doesn't drop enough?

If a post-mitigation test still shows elevated radon, the most common causes are insufficient sub-slab pressure extension (solved by adding a second suction point) or a failed pipe seal. We troubleshoot and adjust systems as needed. In rare cases involving very high pre-mitigation levels or complex geology, additional suction points or a higher-capacity fan may be required — we handle these situations at no additional charge when the issue is within our control.

How long does a radon mitigation system last?

The PVC pipe is essentially permanent — it will outlast the house. The fan is the only component with a finite lifespan, typically 10–15 years of continuous operation. We use fans from established manufacturers that offer warranties. When a fan eventually needs replacement, it's a straightforward swap — the rest of the system remains in place.

Ready to Schedule Your Installation?

Most installations are completed in a single day. Call us or request a free estimate and we'll respond within one business day.

Call Now: (207) 483-5637