Meriden homeowner guide
Interior vs. Exterior French Drains
How the two drainage approaches differ and why the water source should determine the design.
Interior perimeter drainage
An interior system typically collects water near the inside perimeter and directs it to a sump basin. It can manage groundwater and wall seepage without excavating the entire exterior, but it manages water after it reaches the foundation area.
Exterior drainage
An exterior French drain is installed in soil to intercept water. Exterior work may also involve excavation, drainage stone, membranes, protection boards, grading, and downspout management. Access can make this more disruptive.
Neither is universally better
Foundation type, groundwater, soil, slope, discharge options, existing drainage, access, and the leak path affect the decision. Some homes need several improvements; others have a simpler source such as a window well.
Ask for a clear explanation
A proposal should explain the believed source, how the system intercepts it, where collected water goes, maintenance needs, warranties, and exclusions.