If you’re building new, radon prevention is far cheaper to build in than to retrofit later. Here’s what to specifically request.
- Ask specifically for passive sub-slab rough-in piping and a sealed vent to the roofline.
- Request sealed foundation penetrations and an airtight sump cover.
- RRNC features reduce but don’t guarantee low radon — test after move-in regardless.
- A labeled junction box near the vent pipe makes future fan addition simple if needed.
Passive Sub-Slab Rough-In
Ask for a gas-permeable layer under the slab, a sealed vent pipe running from the sub-slab to the attic or roofline, and a labeled junction box near the pipe for easy future fan wiring if a test later shows elevated levels. This passive rough-in typically adds a modest cost during construction versus a substantial retrofit cost later.
Sealing Details
Request sealed foundation penetrations (plumbing, electrical conduits passing through the slab or foundation walls) and an airtight sump pit cover if a sump pump is included, both of which reduce baseline radon entry even before considering an active fan system.
Post-Occupancy Testing
Even with RRNC features included, test after move-in — passive systems reduce but don’t guarantee elimination of elevated levels, and knowing your baseline lets you decide whether adding an active fan (a straightforward addition given the rough-in) is worthwhile.
Get the Features Into the Contract, Not the Conversation
A builder agreeing in a meeting is not the same as a builder being obliged. Ask for the radon-resistant features to appear as line items in the specification and, where possible, as notes on the plan set: the gas-permeable layer, the sheeting beneath the slab, the vent pipe and its termination point, the sealed penetrations, the sump cover, and the labeled electrical box left ready near the pipe. A written spec is what an inspector and a future contractor can both read.
Ask about the change-order cost at the same time, because the honest answer reveals how routine these features are for that builder. The window here is short and it closes hard. Almost every part of this work sits under or inside the slab, so once concrete is poured, the cheap version of the job is gone and what remains is a retrofit.
Photograph It Before the Slab Closes
Take your own pictures at the stages nobody can revisit: the permeable layer in place, the sheeting and how its seams and edges were lapped and sealed, the suction pipe stub and where it sits relative to the footprint, and each penetration through the slab or foundation wall. Include something in frame that establishes location, and note the date.
This is not paperwork for its own sake. If a post-occupancy test comes back elevated, the contractor adding a fan needs to know where the stub is and what it connects to, and that information is otherwise buried. The same photographs, kept with the builder’s spec, answer a buyer’s questions years later without anyone having to take a claim on trust.
FAQ
Do RRNC features guarantee my new home won’t have a radon problem?
No. They reduce entry and make future active mitigation cheap and easy to add, but don’t guarantee elimination — testing after move-in is still necessary.
Not all builders include RRNC features by default — confirm specifically rather than assuming.
These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure, or prevent any disease. Content is for informational purposes only and is not medical advice; consult a qualified healthcare provider before starting any supplement. As an Amazon Associate we earn from qualifying purchases.
