A dimple board is a plastic panel featuring a raised, dimpled surface pattern, installed against a foundation wall to create a consistent air gap that allows groundwater to drain freely down to a footing drain rather than pressing directly against the wall or waterproofing membrane beneath it.
The dimpled texture is specifically engineered to maintain this gap reliably even under the pressure of backfill soil pushing against the panel from outside.
This product is essentially synonymous with drainage board, though the specific terminology emphasizes the distinctive raised surface texture that gives the panel its function.
What Does a Dimple Board Involve?
- A plastic panel with a raised dimpled surface
- Installation over waterproofing membrane on the foundation wall
- A consistent air gap for water drainage
- Connection to the footing drain system
Why Are Dimple Boards Important?
The specific dimensions and spacing of the dimples matter for how much drainage capacity and structural support the board can provide once backfill soil is pushing against it, which is why product selection should account for expected soil pressure and backfill depth rather than choosing based on price alone. A well-selected dimple board maintains its air gap reliably for decades, continuing to protect the waterproofing membrane long after installation.
Some dimple board products also include an integrated filter fabric layer on the soil-facing side, combining drainage and soil filtration into a single installed product rather than requiring separate fabric application. Comparing products based on published specifications rather than price alone tends to produce a better long-term outcome. This straightforward approach helps ensure the product performs as expected for decades.
Dimple Board vs. Protection Board
A dimple board specifically creates a drainage gap through its raised surface texture. A protection board serves a more basic function, simply shielding the waterproofing membrane from physical damage during backfilling, without necessarily providing the same drainage capability.