1. Georgia's Current Building Code Landscape
Georgia adopts the International Residential Code (IRC) as the basis for its residential building standards, with various state-specific amendments. The IRC includes Appendix F, which covers radon-resistant new construction (RRNC) techniques. However, appendices in the IRC are not automatically adopted. They must be specifically adopted by the state or local jurisdiction to become enforceable.
As of 2026, Georgia does not mandate Appendix F statewide. This means there is no blanket state requirement for builders to include radon-resistant features in new homes. However, the EPA has mapped radon zones across the country, and several Georgia counties fall into Zone 1 (highest predicted radon potential). The EPA recommends that all new homes in Zone 1 areas be built with RRNC features.
The counties in north Georgia, including parts of the Atlanta metro area, tend to fall in Zone 1 or Zone 2. This is because the Piedmont and Blue Ridge geological regions contain granite and gneiss bedrock that produces higher levels of naturally occurring uranium, the parent element of radon.
Even without a state mandate, responsible builders in these areas often include RRNC features voluntarily. The cost is minimal during construction, and it provides a significant selling point for the finished home.
2. What Is Radon-Resistant New Construction?
Radon-resistant new construction (RRNC) is a set of building practices designed to prevent radon from entering a home through the foundation. The concept is straightforward: create a barrier between the soil gas and the living space, and provide a pathway for that gas to vent harmlessly to the outdoors.
RRNC is based on the same principles as a full radon mitigation system, but it is installed during construction rather than retrofitted after the home is built. The key difference is cost. Adding RRNC features during construction typically costs $500 to $1,500, while retrofitting an active mitigation system after the fact costs $1,200 to $2,500 or more.
A home built with RRNC features starts as a passive system. The vent pipe relies on natural air pressure differentials and thermal stack effect to draw radon from beneath the slab and vent it above the roofline. If post-construction testing reveals that the passive system is not reducing radon below 4 pCi/L, a small fan can be added to the vent pipe to create active suction. This conversion typically costs $300 to $500 and takes about an hour.
Cost Comparison
Building with RRNC features costs roughly $500 to $1,500 during construction. Retrofitting an active mitigation system later costs $1,200 to $2,500. That means RRNC saves homeowners 50% or more compared to fixing the problem after the fact. For builders, it is a small investment that adds real value to the home.
3. Key Components of RRNC
The IRC Appendix F and EPA guidelines outline several specific components that make up a complete RRNC system. Each one serves a purpose in the overall radon defense strategy.
Gas-Permeable Layer
A 4-inch layer of clean, coarse gravel is placed beneath the concrete slab. This layer allows soil gases to move freely beneath the foundation so they can be collected and vented through the pipe system rather than building up pressure and finding entry points.
Polyethylene Vapor Barrier
A heavy-duty plastic sheeting (minimum 6-mil) is placed over the gravel layer before the slab is poured. This acts as a barrier to prevent soil gas and moisture from migrating through the slab. Seams should be overlapped by at least 12 inches and sealed.
Sealed Foundation Penetrations
All openings in the foundation (plumbing penetrations, utility entries, sump pits, expansion joints) must be sealed with appropriate caulk or other materials. These penetrations are common radon entry points in homes without proper sealing.
Vent Pipe
A 3-inch or 4-inch PVC pipe runs from the gravel layer beneath the slab, through the home, and exits above the roofline. This pipe provides a pathway for soil gas to escape to the atmosphere. In a passive system, natural air currents draw gas upward through the pipe.
Electrical Junction Box
An electrical outlet or junction box is installed in the attic near the vent pipe location. If post-construction testing shows that the passive system needs to be activated, a radon fan can be easily connected without additional electrical work.
4. Local Jurisdiction Requirements
While Georgia does not mandate RRNC statewide, individual counties and cities can adopt Appendix F or create their own radon-related building requirements. This means requirements can vary from one jurisdiction to the next, even within the metro Atlanta area.
Before building or buying a new construction home, it is worth checking with the local building department to find out whether radon-resistant features are required in that jurisdiction. Even in areas where RRNC is not required, many local building officials are aware of the radon risk and may recommend these features.
Some planned communities and subdivisions also include RRNC requirements in their building covenants, regardless of what the local code requires. This is becoming more common in newer developments, particularly in north Georgia counties where radon levels tend to be higher.
Check Before You Build
Building codes change over time, and local jurisdictions can adopt new requirements at any point. Always verify current requirements with your local building department before starting construction. Even if RRNC is not currently required in your area, consider including it voluntarily. The cost is minimal during construction and the health benefits are significant.
5. What About Existing Homes?
Building codes apply to new construction. If you own an existing home, building codes do not retroactively require you to add radon mitigation. However, the EPA recommends that every home be tested for radon, regardless of age, construction type, or location.
If your existing home tests at or above 4 pCi/L, the EPA recommends installing a mitigation system. This is a health recommendation, not a code requirement. There is no Georgia law that forces existing homeowners to mitigate elevated radon levels in their own homes.
That said, radon mitigation becomes relevant in real estate transactions. While Georgia does not require sellers to test for radon, buyers frequently request radon testing during the inspection period. If elevated levels are found, it often becomes a negotiation point in the transaction.
For existing homes, a professional radon mitigation system works on the same principles as RRNC. A pipe is drilled through the slab (or installed in the crawl space), connected to a fan, and routed to vent above the roofline. The fan creates active suction beneath the foundation, pulling radon from the soil before it can enter the home. These systems are effective at reducing radon levels by up to 99% in most cases.
6. Builder and Homeowner Responsibilities
Whether RRNC is required by code or included voluntarily, both builders and homeowners have responsibilities when it comes to radon and new construction.
Builder Responsibilities
- Follow local code requirements for RRNC if adopted
- Inform buyers about radon risk in the area
- Install RRNC features properly if included
- Recommend post-construction radon testing
Homeowner Responsibilities
- Ask about RRNC features before buying new construction
- Test for radon after moving in
- Activate the passive system with a fan if needed
- Retest every 2 years per EPA guidelines
For builders, including RRNC features is increasingly becoming a competitive advantage. Homebuyers are more informed about radon than ever, and a home that comes with radon-resistant construction built in is more attractive than one without it. The cost is minimal relative to the total construction budget, and it demonstrates a commitment to building safe, healthy homes.
For homeowners buying new construction, asking about RRNC should be part of your due diligence. If the builder did not include these features, make sure to have the home tested for radon after you move in. If levels are elevated, a retrofit sub-slab depressurization system can solve the problem, but it will cost more than if RRNC had been included from the start. Our new construction radon solutions team works with builders throughout Georgia. For more on RRNC specifics, see our Georgia RRNC guide. Learn about how long radon testing takes for your new home.
