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how does waterproofing work



As part of our commitment to transparency and communication with our customers, we often like to explain a bit more of what happens behind the scenes, and waterproofing is a classic example of something that’s not generally seen by our customers. But you know it’s there, and so you’re wondering – how does waterproofing work in my new home?


So here’s how it works in the wet areas of our homes (which have a chipboard flooring substrate).



Step 1 involves making sure the surfaces are clean and that the waterproofing membrane is able to stick to the surface properly. This is done by carefully sweeping and / or vacuuming the surfaces and then painting a special primer on it to help the waterproofing really grip. This stuff dries within minutes, so the guys then jump straight onto the next step.


Joins & Gaps

Sealing up the gaps comes next. This is where they use a silicone gun and a very tough but flexible type of polyurethane sealant, sometimes called Sikalfex, and put a bead around all the joints and angles. This includes where the walls join, and the floor joins the walls, and any change of angles at a showerbase for example. Anywhere there’s a gap they’ll fill it with the polyurethane. This part of the process basically creates a continuous surface for the waterproofing.


Apply Waterproofing

Ok, step 3. Apply the weatherproofing. What is the stuff? you’re probably thinking. Its a gooey substance about the consistency of runny honey, with a touch of ‘rubberyness’ to it. Comes in a few different colours, but grey and green are 2 common colours. And it dries into a surface that is tough but flexible – impervious to water. It gets rolled or brushed on, pushed into all the corners and used generously to make sure the film is substantial.


Apply Polyester Reinforcing Tape

When the waterproofing us being put on, and it’s still fresh and wet, a special polyester reinforcing bandage tape gets laid over all the joints and corners – same spots as where the polyurethane was done earlier. The tape is sort of rolled out and pushed into the wet waterproofing to make it flat and stick there. This tape is specially designed to help the waterproofing form a continuous strong membrane over the potentially weak corner joints.


Apply Second Layer of Waterproofing

And the 5th and final step is another complete layer of the waterproofing over everything, especially the tape. Once again, the layer is nice and thick to ensure a good level of imperviousness.


Now might be a good time to pause for a minute and look at why waterproofing is done – what’s the purpose of it all. The simple answer is that it’s protecting the structure of the home – the substrate flooring or the concrete slab and the wall framing.


One thing to realise is what it’s not doing – it’s Not trying to stop water from getting under the tiles. When the tiles are laid, grout is put in and silicone is applied to try and prevent water from seeping under the tiles. But no grout is perfect, and continuous motion of water can carve away grand canyons so of course even the best laid silicone will eventually break down and water can seep under the tiles.


And it’s at this point that the waterproofing comes into its own. It will stop the moisture affecting the structure of the home. But the tiles will come away from the floor, you might say. Yes, exactly what will happen – better that than the structure of the home being damaged! And 100 times easy to fix.


So when the waterproofing membrane has been completed and left to dry for a couple of days, then it’s ready for the tiles to be laid over it. If the work’s been done properly then the tile glue will stick to the waterproofing like a leech and you’ve got that peace of mind that whatever happens the structure behind it all is protected for the long haul even though tiles may come and go.


Waterproofing is not a 5 minute task, but it’s an important one, and even though it’s only seen for a couple of days and then covered forever, it’s a step that any reputable builder simply can’t skip, but sadly we’ve heard and seen first hand of it happening – time and again – and the consequences are disastrous.


Always make sure your builder includes a certifiable waterproofing application under the tiles in your wet areas, or you’ll end up feeling like the astronaut John Glenn with his famous quote when asked how he felt in his rocket “I felt about as good as anyone would, sitting in a capsule on top of a rocket that were both built by the lowest bidder”.
Disclaimer. This blog is our opinion only. The information provided in our blogs is accurate and true to the best of our knowledge, but there may be omissions, errors or mistakes. The information presented in our blogs is for informational purposes only and we are not professionals, so the content we provide shouldn’t be taken as legal advice. We strongly recommend consulting with a professional before taking any sort of action. We reserve the right to change how we manage our blog and we may change the focus or content at any time.

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