When someone says your bathroom is “waterproofed,” do you know what that really means?
If you’ve ever had a tradie or plumber tell you they “sealed it up,” or that the job’s “been waterproofed,” you’re not alone. We hear this daily from clients dealing with leaks that shouldn’t be happening.
The truth is, there’s a big difference between sealing and waterproofing, and misunderstanding that difference could cost you thousands in water damage. Our shower repair specialist Marco has weighed in with his expertise on this to help homeowners with shower leak problems.
Sealing Isn’t Waterproofing. The Most Common Misconception.
One of the biggest misconceptions we come across is the idea that sealing equals waterproofing. We’ve had clients tell us their shower has already been waterproofed when all that was done was a bead of silicone run along the corners. Others mention epoxy grout or some kind of “waterproof paint” and assume that’s enough. Even our own FlexiShield™ epoxy, which is a premium, resin-based sealant we use to lock down wet areas, isn’t technically waterproofing. It’s highly water-resistant, yes, but real waterproofing happens beneath the tiles, before any grout or silicone is applied.
Marco’s seen this misunderstanding time and time again.
“We’ve had plumbers tell homeowners they waterproofed the shower,” he says, “and they meant they ran silicone in the corner. That’s not even close.”
So What Actually Is Proper Waterproofing?
Waterproofing in Queensland falls under a licensed trade, and for good reason. It’s a critical step in protecting your home from water damage, and done wrong, it can lead to rotting timbers, mould, and expensive rebuilds. Wet area waterproofing in Australian homes is also governed by the National Construction Code and AS 3740 waterproofing standard, so there’s a proper benchmark for what “waterproofed” is meant to mean, not just a tradie’s word for it.
Here’s what real waterproofing involves:
- Substrate prep: Surfaces must be smooth and primed (priming is a bonding agent that helps avoid pinholes and adhesion failures)
- Waterproof membrane: A rubber-like liquid membrane is applied in two coats, so they bind together to form a thick, seamless barrier. At Allspex, we use Bostik Dampfix Platinum, one of the most advanced membranes on the market
- Up the walls: Membrane must extend vertically to protect the shower perimeter, especially where the floor meets the wall
- Certification: Make sure you go with someone who has the ability to issue a waterproofing certificate on completion. It’s not mandatory, but knowing you’re with a licensed professional will give you peace of mind
- Bond breaker bandages: These are embedded in joints and corners to absorb movement and prevent cracking
These aren’t standard, but Marco insists on them because they drastically reduce the risk of failure in pressure zones. That insight only comes from doing hundreds of repairs where others do the bare minimum, or worse, cut corners to finish early.
One Coat vs Two Coats: Don’t Fall for the Hype
Some newer waterproofing products claim that a single coat is enough. Marco’s take?
“It might be a great product, but I don’t trust a one-coat system in a wet area that sees daily use.”
Two coats always give better coverage, stronger overlap, and peace of mind. Until it’s proven in real-world conditions over time, he’s sticking with what works.
What About the Screed? Is That Waterproof Too?
Nope. And here’s another big misconception.
Screeding is the sloped concrete bedding underneath your tiles. Its job is to create the correct fall towards the drain. It’s not naturally waterproof, and many tilers don’t even do screeding anymore because of how labour-intensive it is. You can read more about why this step gets skipped in our guide to screeding, the hidden skill.
Screeding isn’t waterproof, unless it’s an Allspex screed blend.
This is where Marco’s 20 years of experience kicks in. He spent years testing different additives to create a screed that is actually water-resistant. Through trial, error, and a lot of buckets, he perfected a method that makes the screed itself repel water.
So even if water gets through your tiles and grout, there’s another barrier in place before it ever hits the membrane.
This added protection, on top of premium prep, membrane, bond breakers, and FlexiShield™ sealant, is why we can offer a 15-year warranty on our work. Most shower repair companies wouldn’t dare.
📌 It’s also worth noting that while many contractors apply their waterproofing membrane on top of the screed, Marco does it the other way around. There’s a good reason for that, but we’ll save it for another post.
The completed waterproofing and screeding stages of a floor first row shower retile repair.
The completed waterproofing and screeding stages of a floor first row shower retile repair.
Are All Tilers Waterproofers? No.
Technically, waterproofing is included in a tiler’s licence. But just like some plumbers don’t touch gas systems, not all tilers are experienced in or like to work in waterproofing.
It’s often subcontracted to someone else, and that’s where shortcuts happen. At Allspex, Marco is both a licensed tiler and a specialist in wet area repairs, and he personally oversees every membrane install.
Why Do Showers Still Leak After Being “Waterproofed”?
Here are just a few common reasons:
- Silicone-only sealing, no membrane underneath
- Poor prep: substrate wasn’t primed or smoothed
- Membrane too thin or not applied in two coats
- No bond breaker bandages in corners
- Screed not sloped properly or not waterproof
- Tiles and grout assumed to be waterproof (they’re not)
- No certification, no accountability
If this sounds familiar, check out our shower repair cost guide or get in touch for an honest assessment. If you’re not even sure where the water’s getting in, our leak detection service is a good place to start.
Final Word from a Shower Repair Specialist: Don’t Trust a Tube of Silicone
“If someone says they’ve waterproofed your shower, ask them what membrane they used. Ask how many coats. Ask if they used a bond breaker in the joints. Ask if they can provide a certificate. If they can’t answer those questions, or if they just point to some silicone in the corner, it’s time to call someone who actually repairs showers for a living.”
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