Can a fireplace make radon levels in my house worse?

Slab-on-grade shortens radon's route

A ranch on a slab has its floor sitting right on radon-bearing soil, with no basement to buffer it, so soil gas has less distance to travel into the living space. Add an open fireplace pulling make-up air, and the pressure difference draws that gas up through slab cracks and control joints. Clyde's 1960s-80s ranches are full of exactly this setup, which is why the fireplace and the radon question are worth looking at together.

Cold-air drainage shared with Canton and Waynesville keeps the heating season long and the pull steady.

The insert upgrade you were already considering

Most of these dated Clyde fireboxes are due for a [sealed insert](/services/wood-to-gas-conversion) regardless — better heat, less draft, a modern look. That same upgrade seals combustion off from the room and stops the fireplace from pulling on the slab, so it fixes the radon contribution as a bonus. River humidity that rusts dampers and degrades these old fireplaces just makes the timing better. An open box replaced by a sealed unit is a clean win on heat and pressure.

Test, then we handle the hearth

Radon sub-slab mitigation is a separate specialty we don't provide. The fireplace side is ours, permitted with Haywood County and pressure-tested as licensed gas work. We're 25 minutes west of the Asheville showroom. Put a cheap test kit on the lowest floor you use, and if it reads high, run the mitigation and the insert together. Call (828) 545-0525.