When I first moved into my 1950s row home in York, the basement had that familiar damp smell that so many older houses in this area share. A friend who worked in home inspections mentioned radon testing casually, and I brushed it off for months. Then I bought a simple charcoal canister test from a local hardware store, and the results came back at 6.4 pCi/L. That number sat right above the EPA action level. Suddenly radon fan installation was no longer an abstract concept. It was the difference between living with a known carcinogen and doing something about it.
Radon is a natural soil gas that seeps into homes through cracks in the foundation, gaps around pipes, and openings in the slab. In York County, the geology is particularly prone to elevated radon levels. The U.S. Geological Survey maps show large swaths of the county sitting on granite and schist formations that release radon at higher rates. The National Radon Program has flagged south-central Pennsylvania as a Zone 1 area, meaning predicted average indoor radon levels are above 4 pCi/L. So if you are a homeowner here, it is not a matter of if you will find radon, but how much.
Understanding Sub-Slab Depressurization
The most common and effective mitigation strategy is sub-slab depressurization. A radon mitigation fan is installed to create negative pressure beneath the concrete slab, pulling soil gas away from the house and venting it safely above the roofline. The process sounds simple, but the execution requires careful planning. You cannot just slap a fan on the wall and call it done. The location of the suction point, the routing of PVC pipe, and the fan itself all matter.
In a typical installation, a contractor drills a hole through the slab, excavates a small radon suction pit below, and seals a PVC pipe into the opening. The pipe runs through conditioned space to the outside, often up the exterior wall or through a closet, and terminates above the roofline. The fan is mounted either in the attic or on the exterior. Every joint is sealed with mastic or foam to prevent air leaks. A U-tube manometer is installed on the pipe to monitor system pressure. If the manometer reads zero or near zero, you know the system is not pulling enough vacuum. If it reads too high, the fan may be oversized or the suction point may be blocked.
The choice of fan matters as much as the pipe layout. A radon mitigation fan like the SUPCO RAD-40 is built for continuous operation and low noise. It draws around 20 to 30 watts, less than a typical light bulb. But not all fans are created equal. Some are rated for higher static pressure, which is important if the pipe run is long or has many elbows. A good contractor will calculate the total equivalent length of the pipe system and match the fan accordingly. Oversizing wastes energy and can actually reduce performance if it creates too much pressure drop across the suction pit.
Basement vs. Crawlspace: Different Challenges
Not every home has a full basement. In York, many older houses sit on crawlspaces. Crawlspace mitigation presents its own set of problems. You cannot simply pull a vacuum on a dirt floor. Instead, the crawlspace must be sealed with a heavy-duty vapor barrier, and the suction point is placed under the liner. The PVC pipe runs through the barrier and connects to the radon mitigation fan outside. Sealing the crawlspace is physically demanding work. You are on your back, often in tight quarters, laying plastic sheeting and taping seams. But skipping that step means the system will draw unconditioned air from the crawlspace rather than pulling soil gas from beneath the house.
I once helped a friend seal his crawlspace in an 1890s stone house in downtown York. The floor was uneven, with old French drain remnants and loose gravel. We spent two days cleaning, leveling, and laying 6-mil polyethylene, then sealing it to the foundation walls with mastic and mechanical fasteners. The radon fan installation itself took half a day. The prep work was the real labor. That is the part most homeowners underestimate. You cannot rush the sealing step, because every leak reduces the system's effectiveness.
Post-Mitigation Testing and Warranty
After the system is running, the next step is the post-mitigation test. The EPA recommends waiting at least 24 hours after fan startup before testing. A short-term test using a summa canister or an activated carbon device like the RAD-40 can give results within two to seven days. The goal is to get radon levels below 2 pCi/L if possible, and certainly below 4 pCi/L. In my own house, the post-mitigation test came back at 1.2 pCi/L. That was a relief, but I still check the manometer every few months to make sure the system is holding vacuum.
A good mitigation system warranty covers both parts and labor for at least five years, sometimes longer. The fan itself should have a separate warranty from the manufacturer. The SUPCO fans, for example, come with a five-year warranty. The PVC pipe and exterior flashing should also be inspected annually. If you see a manometer reading that has dropped significantly, there may be a leak in the pipe or a blockage in the suction pit. A few years ago, a neighbor's system started reading low, and we found that a rodent had chewed through the pipe in the attic. A simple patch with PVC cement and a coupling fixed it.
Why DIY Radon Fan Installation Is Risky
I am a proponent of doing things yourself when it makes sense. But radon fan installation is one area where I strongly recommend hiring a certified professional. The reason is not complexity alone. It is the consequences of getting it wrong. An improperly installed system can actually increase radon levels by drawing soil gas into the living space instead of venting it out. The National Radon Program offers a list of certified mitigators in Pennsylvania, and the York County health department can also point you to qualified contractors.
That said, if you are determined to do it yourself, there are resources. The EPA publishes a detailed guide on radon mitigation for homeowners. You will need to understand how to measure static pressure, how to seal penetrations through cinder block foundations, and how to avoid creating a path for radon to enter through floor drains or sump pumps. A cinder block foundation is especially tricky because the hollow cores act as a highway for soil gas. The suction point must be placed in a way that pulls from all the open cavities, often requiring multiple suction pits or a perimeter trench.
One common mistake is using standard HVAC ductwork instead of rigid PVC pipe. PVC is preferred because it is smooth, non-porous, and does not degrade over time. The pipe should be at least 3 inches in diameter, and all joints should be solvent-welded. The fan itself should be mounted in a location where it is accessible for maintenance but not in a living area. Exterior mounting is common, but the fan must be protected from weather and debris. Flashing around the pipe penetration on the roof is critical to prevent leaks.
Cost, Value, and Peace of Mind
Professional radon fan installation in York County typically runs between $1,200 and $2,500, depending on the complexity of the house. That covers the fan, pipe, sealing materials, and labor. Some contractors offer financing or discounts for multiple homes in the same neighborhood. Compared to the health risks of long-term radon exposure, which is the second leading cause of lung cancer after smoking, the cost is a bargain. A post-mitigation test that shows levels below 2 pCi/L adds real value to your home. When I sold my row home, the buyer's inspector noted the radon system and the manometer reading during the home inspection. It was a selling point, not a liability.
If you live in an older home with a crawlspace or a cinder block foundation, do not assume you are safe. Test first. If the results are elevated, call a certified mitigator. Radon fan installation is not a weekend project for the faint of heart, but it is a permanent solution. The peace of mind that comes from knowing your family is breathing clean air is worth every penny.