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Common Tile & Waterproofing Problems

Recognise the warning signs of tile and waterproofing failure, understand what causes them, and know when it is time to call a professional.

Quick Answer

What are the most common tile and waterproofing problems?

The most common tile and waterproofing problems are leaking showers, cracked grout, loose or drummy tiles, mould around showers, water stains near bathrooms, balcony leaks, pool tile failure, efflorescence and failed silicone joints. Most trace back to waterproofing or preparation issues, so early professional assessment is recommended.

Leaking Shower

What it means
Water escaping the shower area into surrounding walls, floors or rooms below.
Common causes
Failed or missing waterproofing membrane, poor falls to the drain, cracked grout or failed silicone joints.
Why it matters
Hidden leaks can cause structural damage, rot and costly repairs long before they are visible.
When to call a professional
As soon as you notice damp, staining or musty smells — early action limits damage.
Waterproofing

Cracked Grout

What it means
Grout lines that are splitting, crumbling or falling out between tiles.
Common causes
Movement in the substrate, missing movement joints, incorrect grout selection or normal wear over time.
Why it matters
Cracked grout lets water reach the substrate, undermining waterproofing and loosening tiles.
When to call a professional
If cracking is widespread, recurring, or in a wet area where water can penetrate.
Epoxy grout

Loose Tiles

What it means
Tiles that lift, rock or detach from the surface beneath them.
Common causes
Poor adhesion, inadequate adhesive coverage, substrate movement or moisture behind the tile.
Why it matters
Loose tiles are a trip and injury risk and often signal a deeper preparation or moisture problem.
When to call a professional
When multiple tiles are loose or the area is in a shower, floor or high-traffic space.
Bathroom renovations

Drummy or Hollow-Sounding Tiles

What it means
Tiles that sound hollow when tapped, indicating they are not fully bonded to the substrate.
Common causes
Insufficient adhesive coverage, contamination, or movement that has broken the bond.
Why it matters
Drummy tiles are prone to cracking and lifting and can indicate a wider installation issue.
When to call a professional
If several tiles are drummy, especially on floors or in wet areas.
Tile glossary

Mould Around the Shower

What it means
Persistent black or discoloured mould on grout, silicone or surrounding surfaces.
Common causes
Trapped moisture, poor ventilation, failed silicone joints or water sitting in the wrong places.
Why it matters
Recurring mould can be a sign of a waterproofing or drainage problem, not just a cleaning issue.
When to call a professional
When mould keeps returning despite cleaning, or appears alongside damp or staining.
Waterproofing

Water Stains Near a Bathroom

What it means
Discolouration on ceilings, walls or floors adjacent to or below a bathroom.
Common causes
A failing shower or floor waterproofing system, leaking fittings or cracked grout and joints.
Why it matters
Stains often appear only after water has been escaping for some time, so damage may be advanced.
When to call a professional
Immediately — to identify the source before further structural damage occurs.
Waterproofing

Balcony Leaks

What it means
Water penetrating through a tiled balcony or deck into the structure or rooms below.
Common causes
Failed external waterproofing, poor falls, blocked drainage or cracked grout and movement joints.
Why it matters
External leaks can damage framing, ceilings and cladding and are often subject to compliance requirements.
When to call a professional
At the first sign of damp or staining below a tiled balcony or deck.
Membrane systems

Pool Tile Failure

What it means
Pool or waterline tiles cracking, lifting, discolouring or detaching.
Common causes
Incorrect adhesives or grout for submerged conditions, movement, or inadequate waterproofing.
Why it matters
Pool environments are demanding; the wrong materials fail quickly and can affect water tightness.
When to call a professional
When tiles loosen, grout fails, or you notice water loss around tiled areas.
Pool tiling

Efflorescence

What it means
A white, powdery deposit appearing on tiles or grout.
Common causes
Moisture moving through the tiling system and carrying mineral salts to the surface.
Why it matters
It is often a visible sign that water is travelling through the system where it should not be.
When to call a professional
If efflorescence is persistent or accompanied by damp, as it may indicate a moisture issue.
Tile glossary

Failed Silicone Joints

What it means
Silicone in corners and around fittings cracking, peeling, discolouring or pulling away.
Common causes
Age, movement, poor surface preparation or the wrong product for a wet environment.
Why it matters
Silicone joints handle movement that grout cannot; when they fail, water gets behind the tiles.
When to call a professional
When silicone is lifting or mouldy in a shower or wet area, to prevent water ingress.
Bathroom renovations

Related Guides

WaterproofingPrevent leaks with the Watertight System.Bathroom RenovationsFix problems with a full renovation.GlossaryUnderstand the terminology.Contact Nova TilingBook a professional assessment.

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