DRAINAGE MATS & DIMPLE BOARD

How They Work and What They're Used For

DRAINAGE MATS & DIMPLE BOARD

Understanding Modern Waterproofing and Drainage Membranes

Dimple board (Also called Dimpled Membrane) and drainage mats are used to protect foundations as part of waterproofing system. Both are made from HDPE dimpled plastic but the drainage mat also has a geo-textile filter fabric heat-fused to the bottom of the dimple. 

High Density Polyethene (HDPE) is one of the most durable and long-lasting plastics used in construction. It’s environmentally friendly, chemically resistant, and designed to withstand years of ground pressure, moisture, and soil contact—making it ideal for both residential and commercial waterproofing applications.

Both drainage mats and dimple board are mostly used in below-grade structures such as basement foundations, under-slab assemblies, shotcrete shoring, blind walls, green roofs, podium decks, and landscaped areas. They can be applied to a wide range of foundation types, including concrete, concrete block, insulated concrete form (ICF), and shotcrete.

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What is a Drainage Mat?

Drainage mats are part of a waterproofing system that includes a Waterproof Coating. A drainage mat has is dimpled plastic sheet with a filter fabric heat fused on the other side. It's installed over a waterproof coating to protect it from backfill damage and to provide a path for water to drain down to the perimeter drain.

They are typically used in townhouse, duplex, shotcrete, and other commercial construction. They are used behind foundation walls, retaining walls, planters, podium decks, and green roofs.

What do Drainage Mats do?

Drainage mats do a number of things, but the primary thing is to provide a drainage path for water and to protect the waterproof coating.

How drainage mats work?

The dimpled membrane / Drain board create drainage channels, and the filter fabric lets water pass through while blocking soil and fine particles. This prevents clogging and maintains consistent water flow.

The create a permanent barrier and protection for the structure. As part of the waterproofing system, they reduce hydrostatic pressure, protect the waterproof coating, create and provide drainage for the life of the structure.

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SUPERSEAL Dimpled Foundation Membrane

What Is a Dimple Board?

A dimple board, also called a Dimpled Foundation Membrane or dimple membrane, is a HDPE plastic sheet that creates a permanent waterproof barrier around the foundation.

Unlike drainage mats, dimple boards do not have a filter fabric attached. Dimple boards are typically used in residential construction and can installed on poured concrete, block, and ICF foundations.

What does a Dimple Board do / Dimpled Foundation Membrane?

The raised dimples create an air gap that allows water to drain down to the footing while keeping moisture away from the wall surface.

They create a permanent barrier that keeps water out and provide drainage path created by the air gap. This allows the foundation to shift, settle and crack without affecting how it works. Drain boards are commonly installed directly to the foundation can can also be installed over a waterproof coating to provide extra protection and protect the waterproof coating.

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SUPERSEAL Waterproof Coatings