What’s going on with this Pinhole-Pocked Membrane?

Have you ever seen a membrane look like this? What you’re looking at are tiny bubbles formed due to concrete outgassing. Outgassing happens when air and moisture trapped within concrete escape to the surface, often during the curing process. This leads to pinholes and blisters, which can compromise the membrane’s integrity.

The main causes? Outgassing typically occurs when temperatures rise, increasing the pressure inside the concrete. The warmer it gets, the more air and moisture force their way out. It can also happen when coatings or membranes are applied too early, before the concrete has had a chance to fully dry.

How to prevent it?

• Proper surface preparation: Make sure the concrete has been allowed to fully cure before applying a membrane.
• Control temperatures: Try to apply coatings when temperatures are stable, ideally in the cooler parts of the day.
• Use primers: Primers can help seal the surface, reducing the chances of outgassing. Applying 2 coats of a moisture vapour barrier like WPA 560 will greatly increase your success rate in preventing outgassing from occurring.

While outgassing can be tricky, the right precautions can help prevent these defects and ensure a smooth, long-lasting membrane.

What’s going on with this Natural Stone Surface?

The handy thermal camera reveals there is moisture trapped under this natural stone surface. This causes a 'picture frame effect' as the moisture tries to find its way out of the weakest points, which in this case are the grout joints. In this example, there is a high chance of efflorescence forming. Efflorescence is a crystalline deposit of salts that can form when water is present within certain building surfaces. The probable cause is a rain event prior to grouting the natural stone.

What’s going on with this Failing Membrane?

We’ve encountered a failed liquid-applied bitumen membrane on a retaining wall, leading to water ingress into a habitable area. There are likely a few reasons this has happened. First, poor substrate preparation could have left the surface unsuitable for the membrane to bond effectively. Second, the absence of a primer to aid in the membrane’s adhesion properties. Third, the absence of a root barrier protection may have allowed plant roots to penetrate, undermining the membrane’s integrity. Fourth and the most likely cause of the issue, is inadequate membrane thickness, which has caused the membrane to deteriorate prematurely.

While liquid-applied bitumen membranes have their place, they aren't always the best choice for retaining walls. A more suitable membrane system, combined with proper prep, could have prevented this headache! Proper preparation is key to long-lasting waterproofing.

How to prevent it?

• Surface prep: Properly clean and prime the substrate before applying a membrane.
• Root protection: Install root barriers to stop plant roots from damaging the membrane.
• Choose the right system: Select a membrane better suited for long-term moisture protection.

By using the right products and preparation techniques, you can avoid the pitfalls of failed waterproofing systems, ensuring the longevity of your project.

Find out more by reading our Technical Snapshot!