Interior footing drains aka french drains and radon!

Can and do interior footing drains lend to elevated radon levels? Is this a know problem? Have there been any studies or finding with the relationship between the two?

The reference illustration was obtained from for educational purposes only.](

It would seem, as it is an opening through the slab, that it would increase Radon concentration; unless the stack effect has been reduced or the area above the slab has been properly ventilated.
Follow this link for new procedures (for new reidential buliding) designed to reduce radon levels and see some of the resources listed for research.

Look at section 9 specifically:

9.1.8 Channel type (French) drains are not recommended. However, if used, such drains shall be sealed with backer rods and an elastomeric joint sealant in a manner that retains the channel feature and does not interfere with the effectiveness of the drain as a water control system

Any open exposure to earth can allow radon gases to escape into the atmosphere. When you place a container (a house) over the exposed earth, the radon will be captured.

“Footing or French drains” and radon have no direct relation. Understanding what radon actually is, will better answer your question.

I know what radon is Jeff. :wink: Read what i wrote “lend to elevated radon levels” i believe elevated radon levels in the home are or can be related (cause and effect) to the french drain systems installed. Maybe attributed would have been a better word to use instead of related. None the less would you recommend in a house with high levels of radon to seal the french drains. We have in the area one contractor who always installs these drains and i hate (the system not the contractor) them not only for radon but for lacking lateral support of the foundation walls.

Then you know that any exposure to earth can “lend” to elevated levels of radon in the residence. This would be the same for cracks in the slab, voids/openings around penetrations, drainage systems - whatever.

Regardless of the cause of elevated levels, steps should be taken to reduce the radon for obvious reasons.

Sealing the exposures are certainly the first steps, but radon-mitigating equipment may also be necessary at some point.

The relationship between the two occurs when you discover radon later. Interior footing drains (or “footer” drains for those of you from Philly) don’t necessarily cause the radon problem, but they do make mitigation difficult by making it nearly impossible to reduce the sub-slab pressure (due to the interior footing drains leading to outside air), as is necessary for a sub-slab depressurization radon mitigation system to succeed.

Not so easy for a radon mitigation fan to pull a vacuum on a perforated pipe that leads to grade :(. Been there, done that, got the T-shirt.

Thank you Jeff and Nick i hold both of yours’ wisdom in high regards.