kelderdrainage

Kelderdrainage, or basement drainage, is a water management system designed to keep subterranean spaces dry by collecting groundwater and directing it away from the foundation. The primary goal is to reduce moisture, prevent dampness and mold, and protect structural elements and indoor air quality. It is commonly installed in areas with high groundwater, frequent rainfall, or after waterproofing work to relieve hydrostatic pressure on basement walls.

There are two main approaches: exterior and interior drainage. Exterior systems place perforated drainage pipes in a gravel trench around the outside of the foundation, often below grade, and route water to a storm drain or via a drainage ditch. Exterior work is more invasive and costly but lowers the hydrostatic pressure before water reaches the wall. Interior systems install a perimeter drain along the inside face of the foundation wall, directing collected water to a sump pit and pump or to a drainage outlet, thereby protecting the interior from seepage.

Typical components include perforated drainage pipes, a gravel bed or drainage aggregate, a waterproofing membrane or coating, a sump pit, and a sump pump or gravity discharge. Some configurations use filters, inspection ports, and backflow preventers. Installation is specialized and commonly guided by local building codes and standards; professionals assess soil type, water table, foundation design, and climate.

Maintenance involves keeping drainage pathways clear, testing and maintaining the sump pump, inspecting waterproofing, and ensuring outlets are unobstructed. Potential limitations include improper installation, freezing in cold climates, or changes in groundwater patterns that can reduce effectiveness. See also foundation waterproofing and damp-proofing.