The short answer
Radon is increasingly written into new-construction building codes. More states and local jurisdictions are adopting radon-resistant new construction (RRNC) provisions, which call for passive features such as a sub-slab gravel layer, a polyethylene membrane, sealed penetrations, and a vent pipe run to the roof that can be activated with a fan later. States such as Iowa and California have moved in this direction. These features lower the risk of elevated radon but do not guarantee a home reads below the EPA action level of 4.0 pCi/L, so testing the finished home is still needed. Georgia does not currently mandate RRNC statewide, but the trend and the region's elevated radon make it worth understanding before you build or buy.
Table of contents
- 1. The trend: radon rules entering new-construction codes
- 2. What radon-resistant new construction actually is
- 3. States moving toward new-construction requirements
- 4. How model codes spread these rules
- 5. Why RRNC lowers risk but does not guarantee a safe home
- 6. Where Georgia stands today
- 7. Why the trend matters for builders and buyers
- 8. What to ask your builder
- 9. Frequently asked questions
1. The trend: radon rules entering new-construction codes
For most of the history of radon awareness, the rules that existed were about testing existing buildings, not about how new homes get built. That is changing. A growing number of states and local jurisdictions have moved toward requiring radon-resistant features in new construction, usually by adopting provisions from model building codes or by referencing radon-resistant construction standards.
The logic behind the shift is practical. Building radon-resistant features into a home while the foundation is open is far cheaper and cleaner than retrofitting a finished house, and it positions the home so that if testing later shows elevated radon, the fix is simply adding a fan to piping that already exists. As more jurisdictions reach that conclusion, radon is becoming a standard part of the new-construction conversation rather than an afterthought.
2. What radon-resistant new construction actually is
Radon-resistant new construction, often shortened to RRNC, is a set of passive features built into a home during construction. The pieces work together to keep soil gas out and to give the home an easy path to an active system if it is ever needed. The core elements are usually:
- A gas-permeable layer, typically clean gravel, beneath the slab so soil gas can collect and move toward the vent point rather than pushing up into the home.
- A sheet of polyethylene membrane laid over that layer as a soil-gas retarder before the slab is poured.
- Sealing of slab penetrations, joints, and the sump or other openings so radon has fewer easy entry points.
- A vent pipe routed from beneath the slab up through the home and out the roof, sized and located so a fan can be added later.
- An electrical provision near the vent pipe so a fan can be wired in without major rework.
On its own this is a passive system. It relies on natural pressure differences between the soil and the home to draw radon up the vent pipe instead of into living space. The moment a fan is added to that pipe, the passive system becomes an active mitigation system that mechanically pulls radon out from under the slab.
3. States moving toward new-construction requirements
The clearest sign of the trend is that individual states and jurisdictions are moving toward radon requirements in new construction rather than waiting for a single national mandate. States such as Iowa and California have moved in this direction, joining a broader group of jurisdictions that have adopted radon-resistant provisions in some form.
Effective dates and the exact scope of these requirements are set jurisdiction by jurisdiction and are updated over time. Treat any single date or detail as something to verify with your local building department rather than a fixed national rule. The point here is the direction of travel, not a precise code citation.
What ties these examples together is that they are local and state-level decisions layered on top of model codes. There is no single federal law forcing every new home in the country to be radon-resistant. Instead, the requirement spreads as more states and municipalities choose to adopt radon-resistant provisions, which is why the map of where RRNC is required keeps growing year over year.
4. How model codes spread these rules
Most building requirements in the United States do not start as individual state laws written from scratch. They start as model codes and standards that states and local governments then choose to adopt, sometimes with amendments. Radon-resistant construction has worked its way into that ecosystem through model code appendices and consensus standards for radon control in new buildings.
When a state or municipality adopts a building code cycle, it can choose to include the radon-resistant provisions, leave them out, or amend them. That is why coverage is uneven and why the trend advances in steps rather than all at once. As more jurisdictions adopt the radon provisions during their normal code update cycles, the baseline expectation for new homes gradually shifts toward including radon-resistant features.
5. Why RRNC lowers risk but does not guarantee a safe home
This is the single most important point for any buyer or builder to understand. A radon-resistant home is built to reduce how much radon gets in, but the passive system is not guaranteed to bring every home below the action level. Soil conditions, the home's pressure dynamics, how the system was installed, and local geology all affect the result. Two radon-resistant homes on the same street can test very differently.
Radon-resistant features lower the odds of a high reading. They do not replace testing. The EPA recommends testing every home, including new ones built with radon-resistant features, because the only way to know a specific home is to measure it after it is built and occupied.
The good news is that a radon-resistant home is already set up to be fixed. Because the vent pipe runs from beneath the slab to the roof and an electrical provision is in place, activating the system is usually as simple as adding an in-line fan. A home that tests high without a passive system in place is a larger and more disruptive retrofit. That difference is much of the value of building radon-resistant in the first place.
6. Where Georgia stands today
Georgia does not currently mandate radon-resistant new construction statewide. There is no state radon testing law for existing homes, and there is no statewide code requirement forcing every new home to include passive radon features. Some Georgia builders include radon-resistant features voluntarily, and in higher-radon parts of the state it is a sensible choice, but it is not a universal requirement here the way it is becoming in some other states.
Much of metro Atlanta sits in higher-radon EPA zones, driven by the region's granite and uranium-bearing bedrock. The absence of a state mandate does not mean the risk is low. It means the responsibility to ask for radon-resistant features and to test the finished home falls on the builder and the buyer.
Local jurisdictions can also differ, so the safest move is to confirm what applies in the specific county or city where you are building. For a closer look at the local picture, see our guides on radon building codes in Georgia and radon-resistant new construction in Georgia.
7. Why the trend matters for builders and buyers
For builders, the direction of travel is worth tracking even where it is not yet required. Codes get updated on cycles, and a feature that is optional in one cycle can become standard in the next. Builders who already understand radon-resistant construction are better positioned when requirements arrive, and including passive features can be a selling point with buyers who are paying more attention to indoor air quality.
For buyers, the takeaway is that a new home is not automatically a low-radon home. Whether a home has radon-resistant features depends on where it was built and on the builder's choices. Knowing what to look for, and knowing to test regardless, protects you from assuming new construction means no radon. In a higher-radon market like metro Atlanta, that assumption can be expensive to get wrong.
8. What to ask your builder
If you are building or buying new, a few direct questions tell you most of what you need to know about how radon was handled:
- Are radon-resistant features included, and do they follow a recognized radon-resistant construction standard?
- Is there a sub-slab gas-permeable layer and a soil-gas membrane under the slab?
- Is a vent pipe run from beneath the slab to the roof, and is it labeled as a radon vent so it is not mistaken for plumbing?
- Is there an electrical provision near the vent pipe so a fan can be added without major rework?
- Will the finished home be tested for radon, and who pays for activating the system with a fan if the test comes back at or above 4.0 pCi/L?
If a builder cannot answer these, that is useful information on its own. A builder who handles radon-resistant construction routinely will have clear answers, and a builder who has never thought about it tells you to plan on testing and possible mitigation yourself.
9. Frequently asked questions
This article is general information for homeowners, buyers, and builders, not legal or engineering advice. Building codes, state requirements, and radon-resistant construction standards change over time and vary by jurisdiction. Confirm the current requirements that apply to your project with your local building department and a qualified radon professional before making decisions.
