What is a dimple board?

A dimple board is a textured plastic drainage membrane installed on the exterior face of below-grade foundation walls. The board's signature pattern of small domes or dimples creates air gaps between the plastic and the concrete wall, allowing water to flow downward along the membrane surface rather than pressing directly against the foundation.

Water that seeps through soil reaches the foundation wall and encounters the dimple board. Instead of pooling or saturating the concrete, the water runs down the dimpled surface and drains into the footing drain system at the base of the wall. This continuous drainage channel reduces hydrostatic pressure, which is the force exerted by groundwater against the foundation, particularly during heavy rain or spring thaw in Rock County basements.

Dimple boards are typically installed during new construction or foundation repair, covering the wall from the footing to grade level. The material is lightweight, easy to handle, and does not require adhesive in all cases, though some installations use it with a drainage composite. Most dimple boards have a perforated or meshed backing that allows water to pass through while keeping soil particles from clogging the drainage path.

This product is a passive water management strategy. It works alongside foundation drains and exterior grading to keep water away from the interior space. Exterior below-grade waterproofing contractors commonly recommend dimple board as part of a comprehensive foundation protection system, especially in areas prone to wet soil conditions.