10 Common reasons why some waterproofing membrane fails

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Waterproofing failure is one of the biggest claims for construction related issue according to the insurance agency. For concrete waterproofing, membranes are applied to external or internal surfaces to form a barrier that prevents water from penetrating. The application of waterproofing membranes is labor-intensive that requires skilled applicators. However, most failed waterproofing installation is due to poor workmanship – which accounts for 90% of waterproofing membrane’s failure. 

1. Wrong Product Selection and Incompatible Waterproofing Membrane

Choosing the wrong membrane for the intended application of substrate can lead to the failure of the waterproofing application in compatibility of the selected membrane with other products such as wrong usage of primers can lead to de-bonding of the membrane and failure of the waterproofing system. It is advisable to read the product safety data sheet or product application sheet and use recommended products along with it. In some cases, warranty of waterproofing may be void if used with other products that are not specified.

2. Application to Uneven Surface

Always ensure the surface of substrate is even before applying waterproof membrane. Most common waterproofing membrane when applied on uneven surface would have gaps in between or does not have a tight seal with substrate, which leads to water migration between the membrane and the substrate. It is advisable to apply screed, or professional waterproofing system when dealing with uneven substrate. 

3. Application To A Damp Or Wet Surface

Damp or wet substrate would affect the bonding of the membrane to the surface where the water will create a gap between the membrane and substrate, which eventually will lead to debonding. 

4. Application To A Contaminated Surface

Ensure that the concrete surface is cleaned and free from all forms of contamination dust, curing agents, form oils, wax and mold that could affect the bonding of waterproofing membrane with the surface. Applicators and contractors at times did not do a proper cleaning to reduce time and manpower, resulting contamination in between the surface and waterproof membrane resulting debonding.

5. Lack Of Priming

Insufficient priming of the surface prior to installation of the waterproofing membrane can lead to de-bonding. This usually happens when the applicators tried to save costs on the primers or failed to apply it evenly.

6. Insufficient Coverage Or Uneven Application Of A Liquid Membrane

When waterproofing membrane applied unevenly, it prevents establishing a uniform thickness of the waterproofing layer. Certain waterproofing membrane product need to be applied in multiple layers as well. This can result in the failure of the application as thinner parts of the membrane get damaged quicker. 

7. Faulty Overlaps

Not fully bonding overlaps pose potential breach of the waterproofing layer membranes that come apart at the seams allow water to migrate through and penetrate the concrete.

8. Blistering

Caused by insufficient primer on the surface, as a result entrapped air builds up under the membrane causing debonding and formation of blisters on the surface. These blisters are prone to puncture and then result in a breach of the waterproofing layer allowing water to pass through and penetrate the concrete.

9. Puncturing / Tearing

Waterproofing membranes are exposed to a high risk of damage and often this damage occurs in the subsequent stages of the construction schedule. Puncturing often occurs, for example through concrete drilling, backfilling and pipe installation works. Tearing of the membrane usually is the result of building settlement, building movement or expansion joints. Both puncturing and tearing represent a breach of the waterproofing layer resulting to failure.

10. Weathering / Detoration

Many waterproofing membranes deteriorate over time due to exposure to UV rays, harsh environments, aggressive groundwater or permanent ponding, leading to the disintegration of the waterproofing layer and thus the failure of a membrane.

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