Technical Blog

How to install TerraDrainⓇ for wall drainage applications

March 30, 2022

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This sheet drain from Polyfabrics is simple to install.

What is TerraDrainⓇ? 

TerraDrainⓇ is a type of sheet drain constructed from a dimpled plastic sheet with a cuspated surface, combined with a non-woven geotextile layer. 

It provides waterproof membrane protection on foundation walls and other underground structures, as well as providing effective drainage. TerraDrainⓇ is quick and easy to install in a wide range of applications.

In this article, we detail how to install sheet drain for a wall drainage application.

How to install TerraDrainⓇ for wall drainage

  1. TerraDrainⓇ can be installed either vertically or horizontally. To begin, lay the product over the surface with the geotextile layer facing the backfill. 
  2. Hold the sheets in place by either taping, nailing, gluing or simply overhanging the wall while backfilling is taking place. 
  3. For most installations, multiple sheets will need to be used. These can be joined by simply butting up the edges and overlapping the geotextile overhang. Then, secure the joins with reinforced canvas tape.
  4. An alternative method is to overlap the cuspated core by 50mm and secure the geotextile, again using tape, nails or glue. 
  5. Once the layers are in place, the area can be backfilled. 

As you can imagine, this is general advice – always ensure you consult Polyfabrics or a certified engineer for site-specific installation methods. It is the responsibility of the specifier and purchaser to ensure that TerraDrainⓇ is fit for purpose. 

How is TerraDrainⓇ constructed? 

This sheet drain consists of a non-woven geotextile layer and a dimpled polymer layer on either one or both sides. The non-woven geotextile fabric retains soil or sand particles allowing filtered water to pass into the drainage core. This layer covers the dimples and helps to prevent soil particles from blocking the sheet drain, as well as creating an air gap for ventilation.

This simple but effective dimple structure is formed using heat and pressure, resulting in a product that can capture and transport high volumes of water volumes whilst at the same time resisting high loads from earth and formwork.

TerraDrainⓇ provides an excellent way to manage sub-surface water around building foundations. Soil backfill is retained by a filter fabric while allowing water to pass into the drainage core, providing hydrostatic relief. The collected water is then conveyed to a proper collection system, outlet or tank. 

The product also protects waterproofing systems and is often used in basement foundations, behind retaining walls, in planter boxes and for bridge abutments. 

Find out more about TerraDrain

The TerraDrain® geonet system has been used worldwide as an effective drainage layer in landfills, roads, railways and more, eliminating the use of coarse >20mm gravel. With an approximate thickness of 8mm to 12mm, it has a crush strength in excess of 1000kPa. 

For more information on this product and how it can benefit your next drainage project, get in touch with the engineering team at Polyfabrics. 


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