The Ultimate Guide to Radon Safety in New Homes

Buying or building a new home should feel like a fresh start. You get modern materials, updated systems, and the comfort of knowing everything is “up to code.” But radon does not care how new your home is. It comes from the ground, and it can enter even a brand-new foundation through tiny openings you will never notice.

Radon safety in new construction comes down to two simple ideas: you reduce the ways soil gases can enter the living space, and you give radon an easier route to exit the home than the path into it. When you do both, you make testing and mitigation easier for years to come. Keep reading to understand more about radon safety in new homes via our ultimate guide.

What Radon is, Why New Homes Face It

Radon is a natural, radioactive gas that is the result of the decomposition of uranium in soil and rock. It can move through the ground and collect beneath buildings. When it finds a pathway into a home, it can build up indoors.

New homes typically have tighter building envelopes than older homes. That helps with energy efficiency, but it can also reduce natural air exchange. If radon enters a tight home, it may linger longer than you expect. The key is not to assume “new” means “radon-free,” because radon risk depends on site conditions and pressure dynamics, not the age of the structure.

Radon-Ready New Construction (RRNC)

Educated builders frequently use the phrase “radon-ready” to describe a home that includes basic features for controlling radon. You can think of it as pre-wiring a future upgrade. If the new home tests high for radon, the system can shift from passive to active with minimal disruption.

A radon-ready setup does not guarantee the home will test low. It simply makes mitigation simpler and less expensive if you need it later. “Pre-plumbed” is another phrase you might hear.

How Radon Enters a New Home

Radon typically enters where the home meets the soil. That includes slab cracks, control joints, gaps around plumbing penetrations, sump lids, crawlspace openings, and the joint where the slab meets the foundation wall. Even when concrete looks solid, tiny pathways remain. Radon follows air movement and pressure differences, so it tends to move from higher-pressure soil areas into lower-pressure indoor areas.

You cannot “seal your way” out of radon risk, but sealing still plays a valuable role. It reduces entry points and improves how well a venting system can control sub-slab pressure. A good seal won’t mean radon-free, but it will mean a lower utility bill.

The Core Components of Radon Safety in New Construction

Collection Layer Beneath the Slab

A radon control system works best when it can communicate across the entire area under the slab. In many builds, the collection layer comes from a permeable base, such as clean aggregate, or from engineered materials that create an air pathway.

All projects need a soil gas collection loop below the sub-floor. This is typically a geotextile drainage matting, like PDS Radon Mat, or a perforated piping system. This loop allows for good air movement under the slab and can route soil gases toward a riser when a fan is installed. For example, builders may specify a soil gas collector mat as the collection medium beneath the slab so the system can move soil gases efficiently to the vent stack.

A Soil-Gas Retarder Over the Collection Layer

A soil-gas retarder (frequently a sealed membrane) helps limit soil gases and moisture migration into the slab. It also improves system performance because it encourages the easiest exit route to be the vent path rather than random cracks and gaps. Not all codes require it, but many methods do. PDS’ Soil Gas Mat is unique in that a vapor barrier is not needed for it to be effective on slab systems (vapor barrier does not inhibit the PDS radon mat system, but it is not required.  Our system works regardless when designed to our spec).

When a vapor barrier is called for, you must choose Class A. Mil thickness is less important than classification and good installation matters more than brand names here. The membrane needs clean overlaps, tight seams, and proper sealing around penetrations.

A Vent Stack That Exhausts Above the Roofline

A passive radon system uses a vertical vent pipe to move soil gases upward and out. The pipe typically starts at a collection point under the slab, rises through interior chases, and exhausts above the roof. This design protects the system and avoids exterior piping that can look incomplete. An experienced designer plans these extraction points with minimal pipe runs and elbows up through the higher floors of the building. Every elbow is a chokepoint that can reduce airflow and increase noise and vibration. Straight runs are ideal.

In a passive system, natural stack effect and wind can move air through the pipe. In North America, you cannot rely on passive airflow all 12 months of the year, which is why this terminology is being phased out, and radon tests are now required under all modern RRNC codes. The real advantage is that you already have a pathway in place if you need to add a fan later.

Electrical Planning for Future Activation

A passive system becomes active when a radon fan pulls air from beneath the slab and pushes it outdoors through the vent pipe. In many radon-ready designs, builders plan for this by placing an electrical outlet or wiring near the future fan location, typically in an attic or other unoccupied space.

This is one of the most overlooked details in new construction. Adding power later can turn a simple fan install into a bigger job, and leaving PVC in an inaccessible space can be a disaster when it comes to activation. Always plan power and always leave room for a fan.

Sealing and Detailing at Common Entry Points

Even with a strong collection layer and venting route, sealing improves performance. A builder can seal slab penetrations, seal the slab-to-wall joint, gasket or seal sump lids, and address crawlspace access points. These details reduce the number of competing pathways and help the system control pressure where it matters. It also saves huge on HVAC bills once the building is occupied.  These seals also ensure that an active system doesn’t draw conditioned air (i.e.. air you paid to heat or cool) out of the home.

Passive vs Active Systems in a New Home

Passive Radon Systems

Passive is old terminology. It’s not reliable in all seasons and since most homes see year-round or winter-only occupancy, passive systems are no longer recommended. A passive system relies on natural forces and does not use a fan. These forces are strongest when outside air is cold and inside air is hot. Passive can provide some reductions when perfectly designed. Radon-ready is the term of the future. Consider your passive system an insurance policy for your home, you’re now radon-ready.

Active Radon Systems

An active system adds a fan inline with the vent pipe. The fan creates consistent suction under the slab, which usually delivers a much stronger and more reliable reduction than passive venting alone. Many homes that test high after construction can achieve safer levels once a sufficient fan size activates the existing system. Active systems also move a tremendous amount of water vapor, which keeps foundations dry and interior air from becoming musty.

When to Test Radon in a New Home

Test as soon as your thermal envelope is sealed and your HVAC system is running. You should not guess your home’s radon levels based on the neighborhood or the age of the home. The only way to know your radon level is to test. Many radon programs recommend testing at least every two years, and testing also makes sense after major HVAC changes, finishing a basement, or significant foundation work.

For a new home, plan a test after the building reaches “normal living conditions.” That means you run heating or cooling as you normally would, and you keep windows closed except for normal entry and exit. If you complete the test before move-in, you can address issues before furniture and finishes complicate access.

How to Make Radon Safety Part of Long-Term Homeownership

Radon safety works best when you treat it as a routine check, not a one-time panic. Schedule retesting on a predictable cadence, and test again after renovations that change airflow or foundation integrity. Keep documentation of your system design, fan model, and prior test results so future homeowners can maintain continuity. January is radon action month for a reason, at PDS, we retest every winter just to be safe. Think of it like a routine oil change or teeth cleaning, it’s not something you want to skip or delay.  EPA guidelines echo this, with the most lax guideline recommending a five year testing interval.

If your home includes radon-ready features, you already did much of the hard work up front. You built a structure that can respond quickly to real test data, which is the most practical way to manage radon risk in new construction.

Keep Your Home Safe with PDS Radon Supply

We hope our ultimate guide helps you understand the ins and outs of radon safety in new homes. Whether you need a gas collector mat, radon fan, or anything else to keep your home safe, PDS Radon Supply is here to help. Browse our website for radon kits and systems, or contact our staff to speak with a radon expert today. Take advantage of our free takeoff form for your dream home and get a quote on RRNC today.