Can I do waterproofing on top of the existing tiles instead of having to redo the flooring completely? (Bathroom | Waterproofing & Tiling)

For many Sydney homeowners, bathroom renovations can feel overwhelming, especially when it comes to waterproofing. A common question we hear is: “Do I need to strip out all the old tiles to install waterproofing, or can I apply it directly over the existing flooring?”

The good news is that in many cases, you can waterproof over existing tiles, but success depends on the condition of the tiles, the waterproofing system, and careful installation. Whether you’re updating a compact apartment in Darlinghurst or Newtown, a family bathroom in Ryde, Lane Cove, or the North Shore, or a high-end ensuite in Mosman or Paddington, understanding the process ensures a durable, long-lasting bathroom without the cost and disruption of full demolition.

Why Waterproofing Matters Even When Tiles Are Already Installed

Bathrooms are high-moisture areas, and even well-installed tiles are not enough to protect your home from water damage. Waterproofing provides a critical barrier that prevents:

• Water penetration into subfloors and walls

• Structural damage that can be costly to repair

• Mould, mildew, and unpleasant odours

In Sydney, this is particularly important in areas like Bondi, Coogee, and Manly, where coastal humidity is high, or in older Inner West apartments in Marrickville, Darlinghurst, and Newtown, where tiles may be original and the substrate aged. Even luxury bathrooms in Mosman, North Shore, and Paddington benefit from a reinforced waterproofing layer, protecting designer tiles and cabinetry.

Can Waterproofing Be Applied Over Existing Tiles?

Yes—but it’s conditional. Here’s what you need to know:

1. Assess the Condition of the Existing Tiles

• Tiles must be firmly adhered with no cracks or movement

• Grout lines should be stable and intact

• Loose or heavily damaged tiles must be removed and replaced

If the existing tiles are unstable, direct waterproofing will not adhere properly, risking leaks and future failure.

2. Select the Right Waterproofing System

• Liquid membranes: Flexible, seamless, and generally suitable for application over fully prepared tiles

• Sheet membranes: Some are compatible with tiling over existing tiles, though additional priming or leveling may be needed

• Peel-and-stick membranes: Can be used in small bathrooms or secondary wet areas, but seams must be carefully reinforced

At MB9, we often use professional-grade liquid membranes for retrofits in Darlinghurst, Surry Hills, and Mosman, as they combine flexibility, adhesion, and durability, even over pre-existing tiles.

Step-by-Step Guide to Waterproofing Over Tiles

Step 1: Clean and Prepare the Surface

• Remove soap scum, grease, and grime

• Repair minor tile defects or loose grout

• Lightly sand or etch glossy tiles to improve adhesion

Step 2: Apply a Compatible Primer

• A primer designed for your membrane is critical for bonding

• Ensures the liquid membrane adheres securely to the tiles

Step 3: Install the Waterproofing Membrane

• Apply the membrane according to the manufacturer’s instructions

• Cover corners, pipe penetrations, and drains with reinforced layers or corner tape

• Apply multiple coats if recommended

Step 4: Allow Proper Curing

• Wait for the membrane to fully cure before tiling or using the bathroom

• This ensures a watertight, long-lasting barrier

Step 5: Re-Tile if Desired

• Use flexible thin-set mortar compatible with the waterproofing membrane

• Include expansion joints at walls, corners, and drains

Advantages of Waterproofing Over Existing Tiles

1. Cost Savings – Avoid the expense of removing old tiles

2. Reduced Disruption – Faster installation with less mess

3. Structural Protection – Preserves the underlying flooring

4. Eco-Friendly – Minimizes construction waste

Sydney-Specific Context

• Inner West (Darlinghurst, Newtown, Marrickville): Retrofitting over tiles is common in apartments to minimize disruption and save costs.

• North Shore (Mosman, Lane Cove, Ryde): Family bathrooms often have larger layouts; liquid membranes provide reliable waterproofing without floor demolition.

• Eastern Suburbs (Paddington, Bondi, Vaucluse): High-end bathrooms with designer tiles benefit from professional membrane application to preserve aesthetics and functionality.

Maintenance Tips After Waterproofing Over Tiles

• Inspect grout lines and corners periodically for cracks or movement

• Maintain exhaust fans to reduce moisture and humidity

• Avoid harsh cleaning chemicals that could affect membrane adhesion

• Keep floor drains clear to prevent water pooling

Proper maintenance ensures your retrofitted waterproofing continues to protect your bathroom for years, even in Sydney’s humid coastal environment.

Final Thoughts

Applying waterproofing over existing tiles is a practical, cost-effective solution for many Sydney bathrooms, but it requires careful assessment, professional installation, and quality materials. When done correctly, this approach allows homeowners to retain existing tiles, minimize disruption, and maintain a fully watertight bathroom.

At MB9 Australia Pty Ltd, we specialize in bathroom renovations, tiling, and waterproofing for homes across Sydney—from Inner West apartments in Darlinghurst and Newtown to luxury North Shore and Eastern Suburbs ensuites. Our team ensures every project is safe, compliant with AS 3740, and built to last.

For professional advice, expert installation, and complete bathroom renovation services, visit www.mb9.com.au to find out more information about kitchen renovation and bathroom renovation services from MB9 Australia Pty Ltd.