Best waterproof membrane

I often get asked the question, "What are the different types of waterproofing membranes, what is the best waterproof coatings to fix water leaks for roof, my balcony, basement, retaining walls.

There are three basic membranes on the market. There's a lot more but those three that sort of come out more commonly.

Sheet waterproof membranes

Torch On Membranes – these are Sheet Membrane which is commonly welded with heat torches.

Bituminous Sheet Membranes commonly bonded with an adhesive.

Liquid Applied Membranes – spray apply or brush & trowel application.

Liquid waterproof membrane

Liquid Rubber is an Elastomeric, Seamless & Flexible One Coat Spray On Waterproof System for Roof, Balcony, Retaining Walls & Basements.

Some of the advantages of using liquid membranes are numerous but to try and short circuit it, they're flexible. This is a major part of it.

            They move and rake with the building. They are able to be applied in to areas which other sheet type membranes can't be. They can be terminated and bonded to the surface that you're putting them on to. Sheet membranes don't always allow that to happen.

            It's not really a competition between sheet and liquid, but I'm trying to give some of the advantages of using liquid, which is why we do use liquid membranes.

Liquid membranes also are quite quick when need be. If the weather conditions allow, we can do about a 1000m2 in a day, which is pretty substantial coverage.

We're in, we're out. We get the job done, and it's curing out pretty quickly with our instant set material.

​

            The bonding side of it is critical as far as waterproof membranes. Often other types of membranes will de-bond over a period. Then once they de-bond and start to leak, you can end up with a waterbed type effect. The water leak might be some many meters away from where it actually comes in to the building, which is a crucial part of it.

            Everybody might look for a leak at point A but it's actually coming out at point B. Whereas liquid membranes, are fully bonded to the surface. If there's a leak, if someone does puncture there membrane somehow, the leak will be where the puncture is. 

You can easily rectify it and repair it in a flash. That's a very, very good way to go about using liquid membranes.

The footings of the basement and retaining walls are critical. It's usually the "live" joint as we term it. That's the joint between the slab or the footing and then the wall is in place on top of that.

            This is usually where a leak will occur if it's going to leak. Particular attention is paid by all our applicators. FEW methodology is to get down on that by hands and knees basically and get right in to that joint with brush on material. This is then applied thoroughly in to that joint to make sure that that joint will not leak. Even if you don't put another membrane on it that joint will not leak. This is important.

            What we do is we get right down, get it coated, get two or three coats on there, and prepare it up. If it's a nice clean junction, we'll actually use a polyethylene fabric on that as a reinforcement barrier as well that's embedded in to the liquid rubber. Then once that's done, the overall membrane is applied over the top.

Effectively on that joint, you patch over about five or six coats of membranes. You can understand it's a very substantial part of the job and a very substantial coating that goes on it in retrospectively.

            After that's done, the coatings are on and they're all cured, we then use a protection sheet to protect that beautiful work that's all just being done. The protection sheet that we use is a sticky back material, which means it's a peel and stick. You rip the backing of it, stick it on the membrane so that it doesn't shift and move about when the excavators are coming back in to backfill those areas.

            This is critical because otherwise, vines, stones, and things can get down the back of conventional type protection sheets that will cause an amazing amount of damage to the membrane. This will puncture the membrane and start to leak.

            Quite often, I'm being faced with builders who think they know what they're doing. They'll put the protection sheet in, backfill with scoria or crushed rock, and so on. Then after it sets out, it's leaking. Why?

            Once it's dug out, we understand why because you pull the protection sheet out. It's full of stones and everything behind, lots of little holes in that membrane that's all going on there. It's not just our membrane, this is other membranes as well. It's critical to protect the membrane, very often overlooked.

The practices for doing retaining walls and basements are critical. In these areas, they're going to be usually backfilled so that you get one shot at doing this and that's it.

The preparation is paramount. The surfaces must be absolutely clean, preferably as dry as possible. Our material will take some minor amounts of moisture but generally they need to be bone dry.

            This is always a challenge because they're underground usually. Of course, with inclement weather, you have water coming in all the time.  It needs to be carefully planned. Anybody in construction needs to prepare it properly and think about how they're going to do this. It's always disregarded and disrespected actually in the industry.

            The best way, simplest way is keep it clean. Keep it dry. Keep the surfaces smooth and as harmonious as possible so the membrane will bond to it and you don't have little holes and divets to fill up all the time. This is a paramount part of preparation, which is our meticulous way. All our applicators go about and are trained in this fashion.

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.

Membranes will last in varying degrees. The average life span of most membranes is around 25 years to 30 years. The industry sort of dictates a 10-year warranty on everything. It seems to have locked in on everything. Yes, we offer a 10-year warranty. If we need to, we can offer 10 years, 15 years, 20 years or 25 years if we need to. That's sort of the going situation as far as our terminology for warranties if you like.

            But the reality of it is if you’re going to put a membrane down, you really want it to last. We use high quality materials, not the cheapest on the market I can tell you that, but they certainly are a high quality material. The reason we do that is we want them to last.

As the consumer is using this product, again, at the end of the story, they don't really want to be calling us back in 10 years, 15 years to say, "The membrane's broken down. It doesn't work."

            Given that, the timing on it will vary depending on its use, of course. It's like putting that carpet in your home. If you just traipse over it and you bring the army through it every day, it's going to last a very short time. Isn’t it? If your old couple that use it every day now and then potter about your carpet, it's going to last forever pretty much.

            This is the same analogy it goes with membranes. It's a wearable surface like any other no matter what membrane goes down. It's subject to wearability. It's subject to how it's treated afterwards. They do get mashed about by other sub trades behind.

 For example, I'm not putting it down but the air-conditioning guys and people working on the roof, they tend to be a little bit rough, put the tool boxes down and gouge in to the membrane, throw down spanners, throw down hot materials, drills holes at a metal and the hot metal goes down, burns through the membranes. This is all membranes. It's not just ours.

            We see atrocities all day every day. I'm not going to tell you. It does wind us up. People should be more careful with membranes but if they are, they last for a very, very long time.