What to Expect During Radon Mitigation in Huntsville

How does Radon Mitigation work?

Radon mitigation pulls soil gas from beneath your slab and vents it above the roofline, where it dilutes harmlessly. A fan creates constant suction, and a pipe runs from the sub-slab to outside. The system runs 24/7 and drops radon levels by 90% or more.

Radon is a radioactive gas that seeps up through the soil. It enters your house through cracks in the foundation, gaps around pipes, and the sump pit. Once inside, it builds up. The only way to stop it is to intercept that gas before it gets inside. That is what a mitigation system does.

The core of the system is a PVC pipe that goes through the slab floor into the gravel or dirt below. A fan mounted on that pipe (usually in the attic or outside) runs continuously, creating a vacuum under the slab. That vacuum pulls the radon-laden soil gas into the pipe and sends it up and out above the roof. The gas never enters your living space.

In Huntsville, most homes are built on slab-on-grade foundations, but we also see crawlspaces and basements in older neighborhoods like Twickenham and the Five Points area. Each foundation type needs a slightly different approach, but the principle is the same: depressurize the soil under the house and vent the gas safely above the roof.

A typical system uses a 3- or 4-inch PVC pipe, a fan rated for continuous outdoor use, and a manometer (a U-shaped tube with colored fluid) that shows the system is working. You will see that manometer in your garage, basement, or utility room. If the fluid levels are even, the system has lost suction and needs service.

The EPA recommends fixing a home if the radon level is 4.0 pCi/L or higher. In Huntsville, levels can vary wildly even between neighboring houses on the same street. A house on Monte Sano might test at 2.0 while a house a quarter mile away hits 12.0. That is why every sale and every new construction should include a test.

The system is not complicated, but it must be installed right. A bad seal at the slab penetration or a fan that is undersized for the house can leave you with a system that runs but does not lower the radon. That is why you want a crew that knows Huntsville soils and foundation types.

Step-by-step: what to expect

The job starts with a free on-site inspection, then the crew installs the pipe through the slab, mounts the fan, seals the pipe penetration, and runs the vent up the side of the house or through the garage to above the roofline. A post-installation test confirms the system works.

First, the installer walks your property and decides where to cut the slab. They look for the best spot: close to an exterior wall so the pipe can exit the house cleanly, but away from plumbing and electrical lines. They also check the attic to plan the vent path. This inspection takes about 30 minutes.

Next, the crew drills a 4- to 5-inch hole through the concrete slab. They use a core drill with a diamond bit. It is loud for maybe 10 minutes, and it kicks up a little dust. They vacuum the dust immediately. If your slab has radiant floor heating or post-tension cables, the crew needs to know beforehand. Those require special handling.

After the hole is open, they dig out a small pit beneath the slab. That pit gives the fan a place to pull from. They insert the PVC pipe, seal the gap around it with hydraulic cement or a urethane sealant, and let it cure. That seal is critical. If it leaks, the system pulls air from your house instead of the soil.

The pipe then runs to the fan. In Huntsville, most fans go in the attic because the climate is mild enough that condensation is not a big issue. The crew supports the pipe with strapping every few feet, runs it through the roof flashing, and caps it with a vent hood that keeps rain and critters out. The fan itself is wired to a dedicated outlet or hardwired into a nearby circuit.

The whole process takes one crew about four to six hours for a typical slab-on-grade house. For a two-story house with a steep roof, or a house with a crawlspace, it can take a full day. The crew cleans up after themselves. You will see a new pipe on the side of your house or coming out of your roof, and a manometer on the pipe in your garage or utility room.

After installation, the crew runs a short-term radon test (usually 48 hours) to confirm the level dropped below 4.0 pCi/L. Most systems in Huntsville bring levels down to 0.5 to 1.5 pCi/L. You get a written report with the before and after numbers. If the level is still high, the crew adds a second suction point or adjusts the fan.

• Core drilling takes 10 minutes. Dust is minimal and cleaned immediately.
• Pipe runs up the exterior wall or through the garage. In Huntsville, exterior runs are common because they keep the pipe out of living space.
• Fan is mounted in the attic or on the exterior wall. Attic mounting is quieter.
• Manometer shows system status at a glance. Check it monthly.
• Post-installation test is included. You get a report.

How long does Radon Mitigation take?

The actual installation takes one crew four to six hours for a typical slab-on-grade house. A two-story house with a steep roof or a crawlspace can take a full day. The post-installation test adds 48 hours after the system is running.

The installation itself is the short part. The crew shows up in the morning, works through the morning and early afternoon, and is usually done by mid-afternoon. They are not tearing up your whole house. They drill one hole through the slab, run the pipe, and mount the fan. That is it.

What can stretch the timeline is the roof pitch and the attic access. A 7/12 roof forces the crew to use rope and use, which adds time. A house with a finished attic or a tight crawlspace can add another hour or two just getting the pipe routed. In Huntsville, older homes in the Medical District often have plaster walls and limited attic space, which slows things down.

The post-installation test is the real wait. You cannot rush it. The EPA protocol says the test must run for at least 48 hours with the system running. During that time, keep windows and doors closed as much as possible. Do not run attic fans or window fans. The test measures the lowest level the system can achieve under normal living conditions.

If the test shows the level is still above 4.0 pCi/L, the crew comes back to add a second suction point. That is rare in Huntsville, but it happens on large houses with multiple foundation sections or on houses built on fill dirt. The second visit adds another half day.

From the initial inspection to the final test report, figure on about a week. The inspection and installation happen in one or two days, then the test runs for two days, then the lab processes the results. Most companies email the report within 24 hours of the test ending.

One thing homeowners often get wrong: they think the system needs to run for a week before testing. It does not. The fan starts pulling immediately, and the radon level drops within hours. The 48-hour test is just the standard protocol to get a reliable reading.

Common questions about the Radon Mitigation process

Frequently Asked Questions