Plastic Dimple Drainage Board

Plastic dimple drainage boards (also known as dimple mats) promote water flow away from a foundation and stop soil moisture intrusion. They also reduce the need for expensive full-height gravel.

These HDPE sheets have a non-woven geotextile bonded to their dimples to filter soil water. Most are perforated, and some are needle punched. However, unlike air gap membranes, they require another product to act as a waterproofing course.

Waterproofing

Dimple drainage boards, also known as a perforated plastic sheet, provide an excellent alternative to traditional gravel-filled trench drains. They are ideal for gardens, road subgrades, tunnels, reservoir anti-seepage building foundations, and other projects requiring a stable waterproofing solution. This type of drainage system uses a special molding plastic sheet with holes in the upper sides to retain and drain water. The excess water is drained off the surface, while the retained water passes through the hole-filled plates and into the soil.

Construction moisture and water vapor that seeps through the footer wall insulation and into the basement can condense on the dimpled membrane. This membrane can then direct the moisture down to the basement’s interior drains or to the footer drain.

This is an excellent option for retrofitting old, damp basements. It’s easier and more cost effective to install than a spray-applied air gap membrane. It’s also durable and sustainable. It doesn’t degrade over time or corrode fasteners like many fluid-applied products.

Installing a dimpled membrane doesn’t require any special tools or training. It can be mechanically affixed with a ramset gun or a hammer and nails, and it’s flexible enough to bend around corners without cracking. Once in place, it’s a good idea to add a Plastic Dimple Drainage Board layer of polyguard below-grade waterproofing. This will ensure that the dimple membrane isn’t damaged by movement and expansion of the foundation walls.

Drainage

Dimple membranes are great for preventing moisture intrusion in the basement walls. They direct groundwater and construction moisture away from the foundation walls, allowing it to fall freely through the perforations and channeled down to drains. They can also be used to prevent rainwater from seeping into the cove joints (where the wall meets the floor) or concrete block walls.

These plastic waterproof membranes are extremely durable and long-lasting. They can withstand the elements, such as snow or high winds, and can resist the penetration of soil acid and alkali. They are also resistant to weeds, plant root thorns, and bacteria. They provide protection against damage to the basement exterior walls when backfilling.

When installing a below-grade drainage system, it’s important to consider the amount of water that needs to be moved and the level of resistance to hydrostatic pressure. For example, the RESISTO BELOW-GRADE DRAINAGE BOARD can withstand up to 6,000 lb/ft2.

When installed properly, a dimple membrane prevents groundwater, construction moisture, and vapors from entering a basement, keeping it dry and safe for living space. It’s ideal for retrofitting damp basements when excavation isn’t feasible, as it can be placed inside the wall. Pieter Greidanus at Armtec notes that impermeable dimple mats should be part of a complete drainage system, including a footing drain and perimeter drainage.

Insulation

Dimple membranes are a popular alternative to air gap membranes because they can be installed in any weather, and contractors don’t need expensive spray equipment or face health risks from solvents. They’re also more durable than fluid applied membranes, and will stand up to the rigors of backfilling and construction.

These membranes are molded from high-density plastic to create a breathable membrane that prevents moisture intrusion. The “dimples” on the membrane allow walls to breathe and condensate moisture so that it falls down into a basement’s drainage system, instead of migrating back toward the wall itself.

The breathable nature of these membranes also allows them to perform a key function: They can be used to direct water away from a building’s foundation footings, keeping groundwater at a safe distance. This can eliminate the common issue of water seepage that occurs at the critical basement/footing cold joint, gabion wire mesh suppliers a condition known as “water blowing” that leads to mold and structural damage.

Many manufacturers offer a variety of different sizes and thicknesses of these membranes, making it possible to find the right product for your needs. For example, JDR Enterprises makes a membrane called J-Drain, and it’s commonly used for residential basements, as well as commercial foundation projects up to 50 feet below grade. Other manufacturers of dimple drain sheets include Cetco’s AquaDrain, American Wick Drain’s TremDrain and MiraDrain by Carlisle.

Heat Preservation

This is a plastic drainage board that has been heat treated to achieve an effective thermal barrier. It helps reduce moisture in the wall, protects building materials and prevents cold air from entering the basement. It also improves the efficiency of the heating and cooling systems in a home. It can be used in both exterior and interior applications to prevent back fill from touching a foundation wall.

Unlike spray-applied products, dimple membranes do not require expensive breathing filters or safety equipment. Builders can install them quickly, allowing them to extend their work season. They are easy to clean and can be installed in any weather conditions. They are durable for the lifetime of a structure, which can reduce callbacks and expensive repairs caused by damage to spray-applied waterproofing membranes.

While dimple drainage boards can prevent water from seeping through a basement foundation wall, they are not the only thing that needs to be done to keep walls dry. It is important to use a below-grade drainage and systems solution that includes a footing drain system with perforated 4-inch piping surrounded by crushed stone and a filter fabric “burrito.” This will help convey groundwater to the drain and away from the critical wall/footing contact point. It is also helpful to build a sloping lot, which will allow groundwater to flow down toward the drains and to daylight or a basement sump pump.