Waterproofing / De-watering Systems
Waterproofing or de-watering systems that are installed in homes can provide the toughest conditions for installing successful radon mitigation systems to protocols. The de-watering industry typically installs a weep or drip edge along the inside walls of the house, in addition to new drain-tile with gravel-field. This edge provides an open space to allow water to come in from the outside of the house through holes they have drilled through the wall, and run to the inner drain-tile and sump-crock. This actually creates open areas to the sub-slab and gravel areas outside the house equivalent in size to two or more open sump crocks.
The intent of a certified mitigator is to close all open areas to the exterior of the house in order to prevent pressurized soil gasses outside and under the house from entering the house through openings or cracks. In short, the two industries are at opposite ends of the spectrum in their business goals. The de-watering company’s intent is to hold areas of the house open to the outdoor soils to help drain water to the sump crock. The radon mitigator’s need is to close off all areas of the house to the outdoor soils to prevent soil gasses from coming into the house, or… post-mitigation, from pulling air from the house via the mitigation system.
The simple solution would be to close these de-watering system openings in order to properly install a radon mitigation system. Unfortunately, over 90% of de-watering companies will void the warrantees on their system if any “changes” are made to their work. We always insist that a home owner get “written permission” from a de-watering company before we touch any system…if changes are necessary. In most instances, changes to a de-watering system is not necessary.
RMES installs all mitigation systems in homes with de-watering systems using central slab or floor draw-points. This puts the major system suction as far from the drain-tile and weep edge openings as possible, reducing the chance of pulling air out of the basement and back-drafting. We also highly suggest that any home with this “combination” of open floor areas and a radon system, also have a carbon monoxide detector installed around the furnace and hot-water heater to detect unwanted gases from building inside the house if household air starts to be limited over time.