Waterproof correctly now, avoid disaster later

Master Builders ACT continues to observe recurring, yet preventable, issues arise that related to waterproofing installations on residential and commercial projects. 

Why Waterproofing Matters
Waterproofing is more than just keeping water out, it’s about protecting your client’s home and long-term investment and forms part of the structure of the building. For builders and contractors, compliance with Australian Standard AS 3740:2021 is critical to delivering high-quality, durable structures. 

Proper installation of waterproofing systems and ensuring correct falls in wet areas help prevent damage that can lead to costly repairs, especially during the builder’s warranty period. 

Common Issues  

• Incorrect installation of water stops at bathroom and shower entries
  → Allows water to leave wet areas and damage surrounding structures. 

• Insufficient fall in the shower area
  → Causes pooling, grout and adhesive breakdown, and increases mould risk. 

• Membrane not applied to the required thickness
  → Leads to premature waterproofing failure. 

• Substrate not properly cleaned prior to membrane application
  → Reduces membrane adhesion and compromises the waterproofing system. 

Preventative Actions 

Members are encouraged to: 

• Review and understand AS 3740:2021 

• Ensure correct placement of water stops at all wet area entry points 

• Check for compliant falls to all floor and shower drains 

• Confirm membrane thickness aligns with product Specifications and Standards 

• Thoroughly clean all substrates before membrane application 

• Document work with clear, dated photographs for your records 

Adhering to waterproofing standards ensures your project is compliant, durable, and legally sound, while reducing your risk of future liabilities. It’s also a key part of maintaining a strong, professional reputation as well as client satisfaction. 

If you have any questions or need further guidance, please don’t hesitate to contact our Workplace Relations Team at: 

📞 (02) 6175 5900
📧 workplace@mba.org.au