For homeowners who have had a basement waterproofing system installed that includes the installation of drain tile under the basement floor around the perimeter of the basement, you need to consider the following.
Installation of the drain tile for most homes will require sections of the concrete basement floor be removed before the drain tile can be installed. Removing the existing concrete exposes the dirt underneath the concrete floor, which causes the release of radon gas into the basement area. Radon will follow the path of least resistance: it will enter you home using the easiest path of entry. This includes cracks or gaps in concrete. Although radon can and will penetrate concrete having a dirt floor gives the levels that already exist under the foundation an even easier way into your home.
When the concrete floor is replaced, most waterproof systems will leave a small one-inch gap between the replaced concrete floor and the basement foundation wall. This open space can become a source for the radon gas to enter your living area.
Homeowners who have had a waterproof system installed should have the basement tested after the installation. For homeowners who are considering installing a drain tile system under their basement floor, it is suggested that you test for radon before and after the waterproof system is installed. If the radon levels become elevated after the drain tile system is installed, you may have to install a radon mitigation system to reduce the radon in your home.