1. Where This Myth Comes From
The belief that new homes are safe from radon is understandable but wrong. It stems from the assumption that radon enters homes through cracks and gaps in old foundations, and that a brand-new foundation would not have those entry points.
This reasoning has two problems. First, even new concrete foundations have natural imperfections, joints, and penetrations (plumbing, electrical, sump pits) that allow radon to enter. Second, and more fundamentally, radon does not come from the building. It comes from the soil underneath it.
Builders sometimes reinforce this myth unintentionally. A builder who says "we built it tight" or "we used quality materials" may leave the impression that the home is radon-proof. But building quality and radon levels are separate issues entirely.
2. Radon Comes from the Ground, Not the Building
Radon is a naturally occurring radioactive gas produced by the decay of uranium in soil and rock. Every square foot of earth contains some uranium, and the amount varies by location. The radon level in any home depends primarily on the geology directly beneath the foundation.
A new home built on granite bedrock rich in uranium will have higher radon potential than an old home built on sandy soil with low uranium content. The home's age is irrelevant. What matters is what is in the ground beneath it.
In fact, new homes can sometimes have higher radon levels than older homes for reasons related to construction practices. Modern homes are built tighter than older homes, with better insulation and air sealing. While this is great for energy efficiency, it also means less natural air exchange with the outside, which can allow radon to accumulate to higher concentrations indoors.
Georgia Geology and New Construction
North Georgia's granite and metamorphic bedrock produces some of the highest radon levels in the state. Many of the new subdivisions being built in Cherokee, Forsyth, and Hall counties sit on geology that produces significant radon. These new homes need testing just as much as any older property.
3. Why New Homes Can Have High Radon
Several factors specific to new construction can actually contribute to elevated radon levels.
Tighter Construction
Energy codes require tighter building envelopes. Less air infiltration means less dilution of indoor radon. An old drafty house might naturally ventilate enough to keep radon lower, while a well-sealed new home traps it inside.
Disturbed Soil
Construction activity disturbs and loosens the soil around the foundation. Loose, permeable soil allows radon to move more freely from deeper layers to the surface and into the home. This effect can be more pronounced in the first few years after construction.
Foundation Penetrations
Even new foundations have penetrations for plumbing drain lines, water supply, electrical conduits, and HVAC ductwork. Each penetration is a potential entry point for radon if not properly sealed. The quality of sealing varies by builder.
HVAC Stack Effect
Modern HVAC systems can create negative pressure in the lower levels of the home, which draws soil gas (including radon) through the foundation. This "stack effect" can be more pronounced in newer homes with powerful, centralized HVAC systems.
4. Radon-Resistant New Construction Explained
Radon-resistant new construction (RRNC) is a set of building techniques that make it easier to reduce radon after the home is built. RRNC does not guarantee low radon levels, but it provides the infrastructure to address radon quickly and cheaply if elevated levels are found.
A typical RRNC system includes a layer of gravel beneath the foundation slab, a gas-permeable membrane over the gravel, a sealed PVC pipe running from below the slab up through the roof, and sealed foundation penetrations. This is called a "passive" system because it relies on natural air convection rather than a powered fan.
If testing shows radon levels above 4 pCi/L, activating the passive system is simple: a radon fan is added to the pipe, converting it to an "active" system. This activation typically costs $300 to $800, compared to $800 to $2,500 for a full retrofit installation in a home without RRNC features.
Some builders in Georgia include RRNC features voluntarily, but it is not required statewide. If you are buying new construction, ask the builder whether RRNC features are included and request documentation of what was installed.
5. When and How to Test a New Home
The best time to test a new home is after construction is complete and the home is closed up. Testing during construction, when the building is open and unfinished, will not give accurate results because outdoor air is freely mixing with indoor air.
Ideally, test within the first year of occupancy. This gives the home time to settle and allows normal living conditions (doors and windows closed, HVAC running) to establish the baseline radon level you will actually be exposed to.
For new home purchases, consider including a radon test contingency in your purchase contract. If the builder will not allow pre-closing testing, plan to test immediately after moving in. A professional 48-hour CRM test will give you accurate results quickly. Schedule a professional radon test to find out where your new home stands.
New Home Testing Tip
If your new home has a passive RRNC system, test before activating it. If radon levels are already below 4 pCi/L with the passive system alone, you may not need to add a fan. If levels are elevated, then activate the system and retest to confirm the fan brings levels down.
6. Protecting Your New Home Investment
Testing a new home for radon is one of the simplest and most cost-effective things you can do to protect both your family's health and your financial investment. A $15 to $30 DIY test or $125 to $250 professional test can identify a problem that might otherwise go undetected for years.
If you are building a custom home, request RRNC features during construction. Learn more about our new construction radon solutions. The cost to include them during building is typically $500 to $1,000, far less than retrofitting a mitigation system later. Even if your lot turns out to have low radon, the RRNC infrastructure provides peace of mind and is a selling point for future buyers.
If you are buying a new construction home from a production builder, ask what radon protection measures are included. Get it in writing. Some builders in higher-risk areas include RRNC features as standard practice, while others do not offer them at all.
