Waterproofing tips – Should contractors apply angle fillet in waterproof works?

Applying the angle fillet

What is angle fillet waterproofing and why contractors need to apply it?

Most common failed waterproofing issues are due to angle fillet Angle fillet are usually applied in bathroom and toilet waterproofing, and at time in balcony. Angle fillet, which is also being called as internal triangle corner section which is applied to suit into the corner where two different surfaces at an angle less than 180 degrees.

The corners of the areas are the weakest point of the waterproofing as it is susceptible to stress from movements between 2 surfaces. If the stress is greater than the waterproofing membrane applied – it will sure to fail. Therefore, the application of angle fillet is to minimize the stress between the surface and to strengthen the waterproofing membrane in the joints.

Some waterproofing contractors usually skip this step to reduce the time and materials use, and resulting in a less effective waterproofing application. 

Angle fillet visual diagram on how to apply

How to apply angle fillet with the right waterproofing membrane products?

Prepare Chemgrout 215 – Cementitious Non Shrink Grout by mixing it with water according to the ratio described for 5 minutes.

Apply Chembond  – Water Resistant Adhesive Bonding Agent and Mortar Additive to the sharp corners of the application area, to increase the adhesion and bonding of surface with Chemgrout 215.

Eliminate the sharp corners with applying 25mm x 25mm angle fillets using Chemgrout 215 to reduce the stress concentrations before applying first layer of Chemflex R-100 waterproofing membrane.

Shaping the angle fillet

Call us to understand more on toilet waterproofing

If you would like any further information about toilet waterproofing, please contact us or send us an email to info@chemind.com.my . Our friendly team of waterproofing specialists pride themselves on providing great service and will be delighted to help.


The preparation of angle fillet often overlooks by a lot of contractors and applicators due to time restrictions and also cost, and it’s hard to detect visually after the application of the waterproofing membrane. Common property owners would not notice it until further later once their waterproofing membrane application starts failing and show sign of leakages. Therefore, it is important to get reputable waterproofing applicators despite the small price differences for a long term peace of mind.

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