New Construction Radon Mitigation (RRNC) in Peoria, IL

What Radon-Resistant Construction Actually Involves

A properly built RRNC system starts below the slab, with a four to six inch layer of clean, coarse gravel or aggregate spread across the footprint before the slab is poured. That layer allows soil gas to move freely underneath the entire foundation toward a collection point, the same principle that makes a retrofit sub-slab system work, except here it is built in from the start rather than dug and sealed after the fact. A durable plastic vapor barrier is laid over the gravel before the slab pour, reducing moisture and further limiting soil gas migration into the slab itself.

A vertical vent pipe, PVC, is embedded into the gravel layer during foundation work and run up through the house, typically through interior chases planned into the framing, and out through the roof, exactly matching where the discharge point would sit on a retrofit system. Because this pipe is planned into the framing from the start, it runs invisibly through closets or mechanical chases rather than being surface-mounted along an exterior wall the way a retrofit sometimes has to be. All slab penetrations, plumbing stubs, and the foundation-to-wall junction get sealed as part of the same phase of construction, closing off the entry points a retrofit job has to hunt down and seal after drywall is already up.

• •Gravel or aggregate layer beneath the slab before the pour
• •Vapor barrier laid over the gravel ahead of the concrete
• •Vertical vent stack embedded and routed through framed chases
• •All slab penetrations sealed during initial construction

Passive Versus Active: Why Many New Homes Skip the Fan at First

In many new homes, the passive system alone, relying only on the natural stack effect created by the temperature and pressure difference between the house and the outside air, is enough to keep radon levels reasonably low without a fan running at all. This is one of the real advantages of building it in from the start: the vent stack, gravel layer, and sealing work exactly the same whether or not a fan ever gets added, so there is no wasted effort either way.

The system becomes active, meaning a fan gets added inline on the vent stack, only if a post-construction radon test on the finished, occupied home shows levels still at or above 4.0 pCi/L. Adding a fan to an already-built passive system is a straightforward job, since the pipe, gravel layer, and roof penetration already exist, there is no cutting into a finished slab required the way there would be for a home that was never built with any passive infrastructure at all.

A Common Gap: Built Radon-Ready but Never Tested or Activated

A meaningful number of new Illinois homes are built with the passive infrastructure in place, gravel layer, vent stack, sealing, but the home is never actually tested after move-in, and the vent pipe simply sits there doing an unknown job. Builders install the passive system to meet code or best practice, but testing and, if needed, fan activation often falls to the homeowner after closing, and it is easy for that step to get lost in the general chaos of moving into a new house.

If you bought new construction in the Peoria area within the last several years and are not sure whether your home was tested after the builder finished, or whether the passive vent stack you can see running through your closet or garage was ever verified with an actual number, that is worth checking. The infrastructure being present does not guarantee the home is actually below the action level, it only means the cheap, easy half of the job was done. Testing, and adding a fan if the number calls for one, finishes it.

For Builders: Why RRNC Is Worth Doing Right the First Time

For builders working in the Peoria area, RRNC infrastructure is inexpensive relative to what a retrofit costs a homeowner later: a modest addition to foundation labor and material during a phase of construction that already involves grading, gravel, and slab work, versus a homeowner discovering an elevated radon level years later and needing a retrofit system cut into a finished, occupied home. Building it in also protects against the awkward conversation of a buyer's home inspector flagging a lack of any radon infrastructure at all on a home that, in a Zone 1 state, probably should have had it.

Coordinating RRNC installation with foundation subcontractors is straightforward once it is part of the standard scope, and it does not meaningfully change the construction schedule when planned from the start rather than added as an afterthought. We work with builders on subdivisions and custom single homes across the Peoria growth corridors to get this built in correctly the first time, along with post-construction testing and fan activation when a finished home needs it.

Frequently Asked Questions