Waterproofing Planter Boxes and Rooftop Gardens

Posted May 11, 2020

Few areas require such diligent waterproofing as the common planter box or rooftop garden.

In recent years it has become even more popular to take advantage of rooftops, balconies and common areas to grow ornamental gardens, trees or even communal vegetable gardens.

Creating environmentally friendly green roofs has become exceptionally popular for many reasons. These reasons include enhancing aesthetics, appealing to a more eco-conscious buyer or tenant, encouraging local bee populations, increasing green spaces, encouraging more outdoor time, appealing to families with young children and often for the practical purpose of growing an edible garden.

The body corporate within a multi-residential property or community is usually responsible for ensuring these areas are properly maintained. Ensuring the water from these planter boxes is properly drained is essential to preventing leaks into adjacent areas, particularly where there are ceilings below. 

Planter boxes are commonly made of concrete or masonry bricks (masonry blocks). Ensuring you choose a waterproofing membrane that is suitable for the environment is critical to ensuring the longevity of your planter box. 

Consider the following tips to ensure your planter box is properly waterproofed: 

1. Consider the best drainage options for your planter box. These may include installing a proper drain and outlet in the bottom of your planter box.

2. Fix any concrete cracks using the proper methods and materials using crack injection prior to proceeding with any waterproofing. 

3. Ensure the planter box is clean and free of debris. 

4. Choose the correct waterproofing membrane based on the area to be waterproofed, be particularly diligent to choose the correct product if the area is exposed to sunlight. 

5. Seek advice from the waterproofing product manufacturer or a professional waterproofing contractor about whether a primer is required. 

6. Apply the first and second coats evenly, paying particular attention to corners where the product may contract and split as they cure. Since a number of environmental factors may influence this shrinkage, consulting a professional is recommended. 

Keeping balconies leakproof

7. Ensure the membrane is protected from any nicks or abrasion by protecting it with a suitable material. The most common material used for protecting the planter box waterproofing membrane is corflute – otherwise known as polypropylene copolymer.  

8. If watering systems are installed, ensure these watering systems are either completely contained within the planter box as a drip-system or that the entire waterproofed area is large enough to catch the water from a sprinkler system. 

In areas where a warranty is required, such as a multi-residential property or multi-residential community, the body corporate should always consider professionally installed waterproofing. Avoiding potential issues with leakages or water ingress into adjacent areas or ceilings below. 

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