What Is a Sub-Slab Radon System and Do You Need One?
If you live in Tennessee, you’ve probably heard about radon gas. Maybe it was in passing during a home inspection or while chatting with a neighbor. But if your home doesn’t have a basement or crawlspace, you likely didn’t give it a second thought. Radon is a problem for houses with lower levels, right?
Many homeowners make that assumption. Basements aren’t so common in rock-soiled places like Middle Tennessee due to high dig-out costs. And therefore? Slab-on-grade foundations are common. No basement, no crawlspace, no radon risk—right? Well. Not quite so fast.
Even if your home sits on a solid slab foundation, radon can still seep in from the soil below. And, because there’s no natural ventilation under a slab, those radon levels can build up silently over time.
So what do you do if your radon test comes back high, and there’s no “downstairs” to ventilate? That’s where a sub-slab depressurization system comes in. It’s one of the most effective radon mitigation solutions for slab-built homes–and, actually, basements, too.
In this guide, we’ll explain exactly how these systems work, what components are involved, and why The Radon Guys design each one for maximum effectiveness, no matter your foundation type.
First, a Quick Refresher: What Is Radon and Why Does It Matter?
Radon is a naturally occurring radioactive gas that forms when uranium in soil and rock breaks down. You can’t see it, smell it, or taste it…but it can build up inside your home without you knowing. Long-term exposure to radon is the second leading cause of lung cancer in the U.S., according to the EPA.
Radon enters homes through cracks, construction joints, and gaps around pipes; that means slab foundations aren’t immune. In fact, without a basement or crawlspace to dilute or disperse the gas, slab homes can trap radon more efficiently than you'd expect
So…What Is a Sub-Slab Depressurization System?
A sub-slab depressurization system (also known as a radon sub-slab depressurization system) is a type of radon mitigation system designed specifically for homes with a concrete slab foundation–whether your home has a concrete basement or sits on a slab-on-grade.
A sub-slab radon system works by creating negative pressure beneath the slab, which pulls radon gas away from your home before it can enter your indoor air.
In simpler terms? It’s like putting a vacuum under your house that sucks out radon gas from the soil and vents it safely outside.
A sub-slab depressurization system is the standard path for radon mitigation for homes with slab-on-grade or concrete basement foundations.
How Does a Sub-Slab Depressurization System Work?
Here’s a breakdown of how a sub-slab radon system operates—and how each component plays a role in lowering radon levels.
1. Creating a Suction Pit
Installation starts with drilling a small hole through your slab to create a suction pit, a shallow cavity under the concrete where radon can collect. This becomes the primary collection zone for radon and other soil gases.
This step requires precision and an expert touch. The Radon Guys assess airflow and soil conditions to determine the best placement and size for maximum draw.
2. Installing a PVC Pipe Network
A network of durable PVC pipe connects to the suction pit and routes radon gas away from your home. Depending on your home’s layout, the pipe may travel through the interior, attic, or exterior of your home—always with attention to both performance and aesthetics.
These pipes are sealed tightly to prevent leaks and to maintain airflow integrity throughout the system.
3. Installing a Radon Fan (System Fan)
The system's real workhorse is the radon fan, which is installed along the piping, typically in an attic or mounted externally.
This fan creates the pressure differential needed to continuously pull air from under the slab and expel it outdoors. It runs 24/7, quietly and efficiently, to keep radon levels low.
4. Vent Exhaust
The system vents the radon-laden air at a safe distance following all EPA and local code requirements. This ensures the gas disperses safely into the atmosphere, far away from doors, windows, or any spot where it could re-enter your home.
TLDR: Why Is a Sub-Slab System the Go-To Radon Mitigation Option?
The sub-slab depressurization system is used by radon professionals internationally, and for good reason:
Highly effective: Reduces radon levels by up to 99 percent in many homes
Non-invasive: Most of the work is done through a single hole in your slab and discreet piping
Low maintenance: Radon fans typically last 5–10 years and require minimal upkeep
Customizable: Each system is designed around your foundation, soil type, and airflow dynamics to ensure optimal performance
This active radon mitigation approach is extremely effective when implemented correctly.
Why Homeowners Trust The Radon Guys for Sub-Slab Radon Systems
Every home is different, and we design each radon mitigation system to match your unique situation. Whether you’re on a slab, basement, or hybrid foundation, our experts assess your layout, soil, and airflow to install a sub-slab depressurization system that actually works and brings your radon levels down.
No guesswork. No shortcuts. Just clean, code-compliant installation with high-performance materials, verified results, and a full warranty for long-term peace of mind.
If your radon test came back high, don’t wait. An expertly installed sub-slab system is one of the most effective ways to reduce radon and protect your indoor air. Get a free consultation today. Fill out our contact form or call us, and we’ll recommend the right setup for your home.
