Waterproofing balconies can be quite tricky. They are often tiled, some aren’t, but mostly they are. People will often ask us, “Paul, can we come in here and put a membrane over the top on those existing tiles?” Obviously, it’s cheaper to do that because you don’t have to remove the tiles and everything else that’s underneath it.

The danger here is that the substrate, being the tiles themselves, needs to be sound. It’s critical that it’s sound because if you are putting any sort of membrane over the top of loose and drummy tiles, drummy being they’re not bonded correctly. If you tap underneath, you make a drumming sound. That’s why it’s called drumming.

If you try to put a membrane over the top of that, there is a very, very good chance that it’s going to come off. The tile will come away with the membrane. In doing so, it will tear the membrane. Even a highly flexible membrane can still be damaged by this sort of occurrences.

We tend to recommend against putting membranes over the top of tiles. There are some minor, specific cases where we’ll do it but only a few. Generally, the balcony should be stripped right back to zero, go right back to bare bones.

That can be right up back to the actual structure, which if it’s a very bad, has been leaking very badly over some years, this is the way to go because you can check the structure, and as certified builders, we can check actually do that. We can check the structure and make sure that it’s not rutted out. There’s been a number of balcony collapses in recent times and unfortunately some deaths. This is something that needs to be checked thoroughly.

If there’s damage, we’ll replace that damage and as Registered Builders we can do that. Once that’s done, we can rebuild the whole balcony from the ground up. We usually use more modern materials that are available on the market today, which is called a scyon board, and that’s a really top notch base to work from.

Once that’s down, we then apply our membrane. We use reinforcing materials in our membrane to make sure that it’s super strong. Then a screed will be applied over the top of that membrane to get the level so the water will run to the draining system, below the tiles, not on top of the tiles. This is a crucial part of tiling.

The biggest misconception for tiled surfaces is that water runs off the top of the tiles and goes to drainage. It does that but that’s not the critical part of it. It also loses its way through the grout lines because even a freshly grouted balcony will shed water first a period of time.

Then the grout will shrink. It will get minor tiny cracks but water will seep in to those cracks, go down underneath the tile and hit the membrane, which is there.

This is a crucial part of this formula because we put a membrane on the bottom. We put the screed down. Then we put a membrane over the top of that screed. Then the tiles are fixed to that membrane. This allows the water then to flow through the tiles.

This is crucial and everybody needs to really pick up their ears. It does flow through the tiles. They might laugh and say, “Oh, now you need silicone. That will stop that.” All the rest of it, it doesn’t work. I guarantee you this.

 I’ve had over 35 years of experience, I’ve seen so many of these jobs with people and really well qualified builders stand there and talk word on the face, “Mate, it will not leak through the tiles,” and I can tell you it does, all right? I’ll get to the point wherever I need to. This is the way I’m going to do it.

 The whole issue is that membrane underneath the tiles needs to be substantial membrane, of course. The water hitting that membrane needs to flow through the draining system. That might be puddle drains, strip drains, whatever it might be. It depends on the design.

Once the water slowly, slowly works its way through to that drain, it will go away, of course.  Now, while it’s doing that, that membrane needs to be able to support water. When I say support, where I mean hold it up. I mean be able to coat with that water over a long period of time. Because as you can imagine, the time that water works its way through the grout lines, gets through the adhesive, and it does work its way through the adhesive.

The adhesive needs to be the right adhesive so it can support that water. Again, it’s got to be a submersible type adhesive. This will then allow the adhesive to remain intact and not re-emulsify, which I see many, many times, and that’s the white stuff coming out through the grout lines. The extra adhesive breaks down with water. The water then moves its way through the membrane.

It’s sitting on that membrane for a very long time. If you grab a bucket of membrane or you look a lot of membranes off the shelf, you’re going to label and say, “This is not for ponding water.” This is a crucial part of waterproofing. Ponding water often destroys membranes.

You might say, “It’s a waterproofing membrane. How can it destroy it?” Well, it does. It’s not designed to hold water. You must have a membrane that holds water. Liquid rubber holds water. It’s designed for ponds, swimming pools, reservoirs and the like. It’s designed to actually contain water. This is a major part of why we use this material.

The water then slowly, slowly, works its way down to the drainage points. The membrane stays intact because it’s suitable. The adhesive stays intact because it’s suitable. Of course, the tiles are made of fortified clay, so that’s not going to be destructed too readily. This is the waterproofing system, and it’s crucial to waterproofing.

Findlay-Evans Waterproofing

A Waterproofing Company That Thinks Construction

Registered Building Practitioner & Certified Waterproofers

P: (03) 8812 2918

E: info@waterproofingfew.com.au

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