Common Causes of Shower Leaks on Why Shower Screens Leaks

Shower screens primarily leak due to issues with their installation and the integrity of the sealing. Here's a detailed breakdown:

 * Improper Sealing: This is the most common reason.
 * Inadequate sealant application: Not enough sealant, or sealant that doesn't completely fill the gap between the screen and the tiles/tray.
 * Incorrect sealant type: Using a non-waterproof sealant (e.g., general-purpose silicone instead of sanitary grade silicone with mold inhibitors).
 * Poor surface preparation: Applying sealant to dirty, dusty, greasy, or wet surfaces prevents proper adhesion.
 * Old or degraded sealant: Over time, silicone can crack, shrink, peel, or become brittle due to age, exposure to cleaning chemicals, and constant wetting/drying cycles.
 * Missing seals/gaskets: Some shower screens use rubber or plastic gaskets/seals along their edges (especially frameless screens). If these are missing, damaged, or not correctly installed, water will escape.
 * Structural Movement:
 * Building settlement: Minor movements in the building can cause walls or floors to shift slightly, putting stress on the shower screen and breaking the sealant bond.
 * Incorrect installation: If the shower screen frame isn't rigid or securely fixed, it can flex, leading to cracks in the sealant.
 * Design Flaws:
 * Insufficient overlap: For framed or semi-frameless screens, if the glass panels don't sufficiently overlap where they meet, water can splash through the gap.
 * Inadequate water retention: Some shower screen designs are simply not good at containing water, especially if the showerhead is powerful or positioned poorly.
 * No or insufficient "hob" or "rebate": Many showers are designed with a raised curb (hob) or a recessed area (rebate) at the entrance to contain water. If this is absent or too low, water can easily escape.
 * Poor door design: Doors that don't close tightly, have worn hinges, or lack effective drip strips can allow water to escape.
 * Drainage Issues:
 * Incorrect fall to the waste: If the shower floor doesn't properly slope towards the drain, water can pool at the edges, increasing the hydrostatic pressure against the seals and eventually finding a way out.
 * Blocked or slow drains: This can lead to water building up on the shower floor, putting more pressure on the seals.
 * Damage to Components:
 * Cracked or broken glass: Obvious, but a significant cause of leaks.
 * Damaged frame: A bent or damaged frame can prevent proper sealing or cause gaps.
Correct Sealing Principles for Shower Screens
The correct way to seal a shower screen is to create a continuous waterproof barrier on the outside perimeter of the screen where it meets the tiles or shower tray.
Here's why and how:
 * Why outside? Water that splashes or runs down the inside of the shower screen should be directed back into the shower area. If you seal the inside only, any water that gets behind the seal (e.g., through tiny imperfections, capillary action, or degradation over time) will be trapped and will eventually find a way to the outside, often behind tiles or into wall cavities. Sealing the outside ensures that any water trying to escape is met with a complete barrier, forcing it back into the shower.
 * Where to seal:
 * Along the bottom edge: Where the screen meets the shower tray or the tiled floor. This is crucial as gravity pulls water downwards.
 * Up the vertical edges: Where the screen meets the wall tiles.
 * Around the frame (if applicable): Any gaps between the frame and the wall/floor.
 * What about the "inside"?
 * For most framed or semi-frameless screens, the design typically directs water inwards. You might apply a very small, neat bead of sealant on the inside bottom edge where the glass meets the frame/tray to help direct water, but the primary waterproof barrier should be on the outside.
 * For frameless screens, a clear polycarbonate or vinyl "drip strip" is often used along the bottom edge of the glass door to direct water inwards.
 * The key is to avoid trapping water between an inner and outer seal. This is why the instruction to "unseal on the outer perimeter" is incorrect and would lead to leaks.
If Waterproofing Isn't Done Correctly (The Underlying Issue)
The shower screen sealing is the final line of defense against water egress. However, it's critically dependent on the primary waterproofing system behind the tiles.
What is correct waterproofing?
Before any tiles are laid, the entire shower area (floor and up the walls to a specified height) should be treated with a flexible, waterproof membrane. This membrane is applied to the substrate (e.g., cement sheeting, plasterboard) and forms an impermeable barrier that prevents water from penetrating into the wall cavities, floor joists, or adjacent rooms. This includes:
 * Preparation: Ensuring the substrate is clean, dry, and structurally sound.
 * Priming: Applying a primer for proper membrane adhesion.
 * Bond Breakers/Reinforcing Fabric: Applying flexible bond breakers to internal corners, floor-to-wall junctions, and around penetrations (e.g., taps, spouts) to accommodate movement and prevent cracking of the membrane.
 * Membrane Application: Applying multiple coats of a liquid-applied waterproof membrane or sheet membrane.
 * Flood Testing: (Recommended but not always done) Filling the shower tray with water for 24-48 hours to check for leaks before tiling.
Consequences of incorrect waterproofing (or lack thereof):
If the underlying waterproofing is not done correctly, even a perfectly sealed shower screen can't prevent major issues:
 * Timber Rot and Structural Damage: Water penetrating into wall cavities or under the floor can cause timber framing to rot, leading to structural instability and costly repairs.
 * Mold and Mildew Growth: Trapped moisture provides an ideal breeding ground for mold and mildew, which can spread behind tiles, into plasterboard, and potentially into living areas. This can cause health problems and unpleasant odors.
 * Efflorescence and Tile Delamination: Water seeping through the substrate can carry mineral salts to the surface of tiles or grout, causing a white, powdery residue (efflorescence). This moisture can also compromise the tile adhesive, leading to tiles becoming drummy or detaching from the wall/floor.
 * Damage to Adjacent Rooms: Leaking water can damage ceilings, walls, and flooring in rooms adjacent to or below the bathroom.
 * Electrical Hazards: Water coming into contact with electrical wiring or outlets behind walls can create dangerous short circuits or electrocution risks.
 * Pest Infestations: Damp, dark areas behind walls can attract pests like termites, silverfish, and cockroaches.
 * Devaluation of Property: Significant water damage and mold issues can severely devalue a property and make it difficult to sell.
 * In summary:
Shower screens leak primarily due to failed or incorrect sealing, often exacerbated by underlying structural movement or drainage issues. The correct sealing method involves creating a complete, external waterproof barrier. If the primary waterproofing behind the tiles is inadequate, the consequences can be severe, leading to significant structural damage, mold, and health hazards, regardless of how well the shower screen itself is sealed.