What are waterproofing membranes?

Bathrooms are the wettest rooms in a house and therefore require special attention to prevent water damage. Waterproofing membranes are an essential element of any bathroom, particularly in areas where water is frequently present, such as in showers and tub surrounds. These thin layers of material are designed to protect the structural elements of a bathroom, such as walls, floors, and subfloors, from mold, mildew, and water damage, thereby ensuring the longevity of the bathroom.


The importance of waterproofing membranes

Water can be extremely damaging to building materials over time. It can cause rot, mold growth, and other problems that can compromise the integrity of the structure. In a bathroom, water is a constant presence, and it can seep into walls and floors through grout lines, cracks, and other gaps. This is where waterproofing membranes come in. By creating a barrier between the water and the underlying structure, they can prevent water damage and ensure that the bathroom remains safe and functional for years to come.

Mold and mildew protection

Mold and mildew thrive in moist environments, and bathrooms are an ideal breeding ground for these fungi. Left unchecked, mold and mildew can quickly spread, be difficult to eradicate and cause health problems for occupants. Waterproofing membranes help reduce the risk of mold and mildew growth by preventing water from seeping into the structure, making sure that the bathroom is a safe and healthy space.

Tile and grout are not waterproof

While tile and grout are often used in showers and other bathroom areas, they are not inherently waterproof. Water can seep through the grout lines and into the underlying structure, causing damage over time. To prevent this, a waterproofing membrane should be installed behind the tile and grout to create a barrier against water intrusion. This will ensure that the bathroom remains protected against water damage, mold growth, and other issues that can arise from moisture accumulation.

Structural protection

In addition to protecting against mold and mildew growth, waterproofing membranes can also help protect the structural elements behind the shower. This includes the framing, sheathing, and other materials that make up the walls and floor. These materials can become weakened and compromised over time if they are exposed to water. By installing a waterproofing membrane, you can ensure that these structural elements remain intact and strong.

Waterproofing membranes from Schluter

Schluter membranes for walls and floors are designed to provide superior protection against water damage. They are made of high-quality materials that are resistant to water and moisture, ensuring that the structural elements of the bathroom are adequately protected. Additionally, Schluter membranes are easy to install and provide a seamless barrier against water penetration, preventing water damage and ensuring the longevity of the bathroom.

One popular waterproofing membrane that is often used in bathrooms is Schluter-KERDI. This product is made of a polyethylene membrane that is covered on both sides with a fleece webbing to anchor the membrane in thin-set mortar. It is lightweight, easy to install, and provides excellent protection against water intrusion. Some of the other benefits of Schluter-KERDI include:

Mold and mildew resistance: The material is resistant to mold and mildew growth, which helps keep the bathroom safe and healthy.

Vapor permeability: The membrane is vapor-permeable, which allows any moisture that does get behind it to evaporate rather than become trapped.

Increased lifespan: By protecting against water intrusion and mold growth, Schluter-KERDI can help extend the lifespan of the bathroom and reduce maintenance costs over time.

KERDI is part of the Schluter®-Shower System, an integrated family of products that that together form a fully bonded, watertight assembly for tiled showers. In addition to this sheet-applied membrane, Schluter offers a suite of KERDI accessories that facilitate the waterproofing of tiled floors and walls, including pipe seals, preformed corners, and waterproofing strips. A convenient KERDI-SHOWER-KIT containing all waterproofing components for your shower is also available. See how you can waterproof your shower using the complete kit here:

KERDI-BAND is a waterproofing strip used to seal butt joints and floor/wall connections.

KERDI-KM and KERDI-SEAL-PS/-MV are prefabricated seals for pipe protrusions.

KERDI-KERECK-F and KERDI-KERS are preformed waterproofing corners.

Schluter also offers KERDI-DS, a bonded waterproofing and vapor retardant membrane that is used in continuous-use steam showers.


Schluter®-Systems offers solutions to common tile installation challenges, including effective waterproofing membranes. Ceramic and natural stone are esthetically pleasing, practical, and durable, but they are not inherently waterproof. Schluter®-KERDI waterproofing and vapor barrier sheets can be installed underneath tile in showers, tub surrounds, and other wet areas, to help maintain the integrity of the tile installation.