Bond Breakers: The Hidden Hero of Waterproofing

In Episode 9 of ARDEX Answers, Chris Brady returns to unpack a frequently overlooked—but absolutely essential—element of waterproofing: the bond breaker. Hosted by Monique Fenech, this episode dives into why bond breakers matter and how they prevent waterproofing system failures at movement joints and wall-to-floor junctions.

What is a Bond Breaker?

A bond breaker is a material that allows for movement in joints by preventing the waterproofing membrane from bonding to both sides of a junction. This is crucial in corners and transitions where building movement is expected. Without a bond breaker, the membrane may crack or shear—leading to costly water ingress.

Types of Bond Breakers

Chris outlines the three common types:

Tapes – Flexible, easy to apply, and suitable for liquid membranes.
Sealant-based systems – Used under membranes to form a flexible joint.
Backer rods and sealants – Often used together for larger movement joints.

Why They’re Non-Negotiable

Bond breakers aren’t optional. They’re a requirement under AS3740 and AS4654.1 standards. They ensure that the membrane maintains its integrity during expansion, contraction, or substrate movement. Neglecting them is a leading cause of waterproofing failure.

Common Mistakes

One common error is overcoating the bond breaker with too little membrane, which results in poor elongation. ARDEX recommends a minimum wet film thickness of 1.5mm over the bond breaker zone.

Final Word

If you’re waterproofing, you’re using a bond breaker—or you should be. Always consult the relevant ARDEX Technical Bulletin and product datasheets for your membrane system. And when in doubt, call the hotline.

ARDEX Technical Hotline: 1800 224 070