Retaining Walls and Planter Boxes

It’s important to waterproof your retaining walls to avoid the buildup of hydrostatic pressure which can cause serious damage to your walls overtime.  

tws retaining walls

How to waterproof your retaining walls and planter boxes

Check with Total Waterproofing Supplies for the correct membrane to use in your area if you are not sure.

This is a generic guide only, giving a basic overview of how to install a membrane.  This information is given in good faith and should NOT be used as a Technical Data Sheet (TDS) or Instruction Sheet.  

When purchasing membranes always download the full TDS sheet and MSDS sheet applicable. All membranes have their own manufacturer’s instruction guide/s,  these must be used when installing membranes.  

You may download this information  from our website or direct from the manufacturer.

planter box waterproofing
  • 1. Ensure the area to be waterproofed is clean and is free of any dirt and is completely dry.
  • 2. Make sure there is enough room to work between the wall and the earth embankment.
  • 3. Fill any construction joints with backing rod and a sealant that is compatible with the membrane (see membrane data sheet).
  • 4. Apply the first coat of membrane to the wall or planter box, (in most cases a primer is not required but check with the data sheet or TWS).
  • 5. Ensure that the membrane extends down on to the footing or slab by 150mm this will prevent the ingress of water through the wall and floor junction at a later date.
  • 6. Allow the membrane to dry, time will vary depending on the temperature and weather conditions. (Check membrane data sheet for a guide of drying times).
  • 7. Apply a second coat of membrane over the area, and allow the membrane to dry before back filling or installing protection board and/or drainage cell system. (Builders plastic is not a form of protection for the membrane as it will not absorb impact from the back filling process or impact from gardening tools, it will simply tear leaving the membrane exposed and vulnerable to damage. (99% of membranes used for these types of application are not UV stable, and will break down under a short time from application so they need to be covered after the application of the second coat or third coat so they are not affected by the UV light).