Often when we go out to inspect a reported Leaking Balcony – we find it is actually the Planter Box that is leaking. Built-In planter boxes, if not waterproofed correctly can deteriorate over time and begin to leak.

When waterproofing a planter box it must be in accordance with AS4654.2-2012 Waterproofing membrane systems for exterior use – Above ground level – Design and installation, Clause 2.7 Planter Boxes.

How to waterproof a planter box

– First you must remove all plants and bag up all soil from the planter box.
– Wash out the planter box (being careful not to flood) and allow to dry.
– Inspect your planter box for any defects and repair any visible cracks, making good the surface of the base and sides.
– Ensure the base of the planter box is graded with falls to the drainage outlet, a screed may be required to correct levels.
– Apply waterproof polyurethane seals to the main junction joints of the planter box to seal up all the joints for continuous membrane application.
– If required, install a Drainage outlet/Puddle Flange into the drain, ensuring it is recessed into substrate.
– Apply waterproof bandage over any polyurethane seals.
– Apply the 2X coats of waterproof Membrane to planter boxes
– Between coats of membrane apply waterproof bandage the main junction joints 80-100mm up the risers. Membrane must be sealed to and terminate into Drainage outlet/Puddle Flange and extend a minimum of 100mm above the expected soil fill level where the Planter Box abuts a wall.
– If the external exposed walls of planter boxes have not been rendered, these can be waterproofed as a secondary measure to prevent failure of the internal planter box membrane. This should then be rendered.
– Once fully cured, reinstall all the existing bagged soil in to the planter box.

SCR does not recommend waterproofing Planter Boxes as a DIY project, as if done incorrectly it can cause costly water damage to your property.

At the first sign of a leak – you should contact SCR Melbourne for a free Expert diagnosis and no-obligation quote for repairs! Click here.