Interior drainage systems are typically installed along the perimeter of a foundation footing or at the lowest point on the foundation wall under the basement slab. This procedure generally requires pipe, stone, pump and re-cementing of the floor. If foundation moisture problems are present, some basement waterproofing contractors may choose to install a form of vapor barrier that attaches to the foundation walls. This allows seepage into the system without allowing soil vapors or ground moisture to escape into the home. It is called a “closed system” and can be installed in lieu of an open drainage system which allows water to enter the system through an open channel.
For years, waterproofers across the country installed open drainage systems. However, in recent years more contractors are now installing only closed systems or converting open systems to closed systems. The Basement Health Association recommends a closed waterproofing system for the following reasons:
1) Radon and soil gases can easily come up through an open system
2) Bugs and other pests can come up an open system
3) Stack effect sucks up ground moisture into the living space through an open system
4) Problems like iron bacteria and mildew seem to flourish in an open drainage system
5) More ground humidity is drawn up through an open drainage systems if the basement also has a dehumidifier
6) Homes with open drainage systems typically have higher heating and cooling costs