Farragut, Hardin Valley and Karns have added a lot of new construction over the last several years, and we get calls from buyers of those homes just as often as we do from owners of older houses in Fountain City or Bearden. The assumption is usually the same: the house is new, so radon should not be an issue. Radon does not know how old a house is. It comes from the ground underneath it, and East Tennessee's geology produces it regardless of when the foundation was poured.
The uranium breaking down in the rock and soil under Knox County is the source, and that has nothing to do with the construction date of the house sitting on top of it. What does change the reading is how the house interacts with that soil: how tight the building envelope is, whether there is a basement, slab or crawl space, and how much of the lower level people actually use as living space. New homes often score worse on several of these factors than older ones, not better.
Tighter construction. Modern building codes and materials are designed to keep conditioned air inside the house, which also means radon that enters has fewer ways to escape on its own.
Finished basements from day one. A lot of new construction in this area comes with a finished lower level built in from the start, rather than a basement that gets finished years later. That means the test placement, the lowest livable level, is capturing a room that is fully in use from the day you move in.
Crawl space construction is still common. Plenty of new Knoxville homes are built on crawl spaces rather than slabs, and a crawl space lets radon enter across the whole footprint of the house rather than through a single slab. Our crawl space mitigation page covers why that construction type behaves differently.
Freshly disturbed soil. Grading a new subdivision loosens soil that had been compacted for a long time, which can open new pathways for gas to move upward. This tends to settle over the first few years, but it does not necessarily mean lower readings while it is happening.
Many builders in this area now include a passive radon rough-in, a capped pipe running from under the foundation up through the house and out the roof, installed during construction in case it is ever needed. If your new home has one, activating it with a fan is a much smaller job than installing a system from scratch. Look for a labeled pipe in the mechanical room or a utility closet before you assume you need the full installation quoted on our mitigation cost guide.
A 48 hour test on the lowest livable level, with the house closed up, is the standard whether the house is brand new or decades old. If you are still under contract, our real estate testing page walks through fitting the test into a normal inspection window, and Tennessee's disclosure expectations are covered on our disclosure guide.
This is a solvable problem and, if there is a rough-in already in place, often a quick one. Builders and sellers frequently participate in the cost when a test comes back elevated during a transaction, and a mitigation system with a written guarantee resolves the issue for good. See our mitigation systems page for how the fix works.
Call (865) 563-8112 and tell us the year built, whether there is a basement or crawl space, and whether you can find a capped rough-in pipe. We will quote the fix over the phone.
Free quotes · Same-week testing · Serving Knoxville, Farragut, Powell, Halls, Karns, Bearden, Seymour, Oak Ridge & Maryville
Call (865) 563-8112