How Waterproof Is Your Shower, Really?

Your shower might be getting you squeaky clean every morning, but a leaky shower could leave you with a huge mess. Mold and other water damage can grow over time and may not be obvious until the damage is done, which is why shower waterproofing is an important part of maintaining a home.

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How Are Showers Waterproofed?

Most people don't think a lot about waterproofing a shower since showers are made from materials like tile, glass and plastic. However, water can seep through even small gaps where materials meet or where drains are installed. There are several options for ensuring that this water doesn’t reach the subfloor or other materials vulnerable to water damage.

Waterproof Membranes

A common modern method for waterproofing a shower involves the installation of a membrane between the shower and home. There are a few common types:

• Liquid waterproofing membranes. An installer paints these on the wall and subfloor before a shower is installed. Liquid membranes work well for complex shower shapes but must be carefully applied.

• Sheet membranes. Sheets of waterproof plastic or other material are applied to the tile backer board to stop water. These are very effective at preventing mold. However, there are still seams between sheets, so careful installation is critical to ensure that water doesn’t escape.

• Foam wallboards and bases. Waterproof foam backer board can be installed directly under shower tiles. Foam bases can also be installed under a shower floor. These provide excellent waterproofing but may limit options for the size and shape of the shower.

Be aware that cement board is not the same as a waterproof membrane. Cement board is a commonly used backer board in bathrooms, but it must be combined with other waterproofing to prevent damage.

Pan Liner Systems

Shower pan liners were standard in many homes in the past, although newer homes tend to have membrane systems. Pan liners are usually made from copper or rubber and are installed under the shower to collect any water that leaks through the tiles or seams. Liners slope towards a weep hole drain that allows water to escape.

Pan liners don’t stop water from leaking through the shower. Instead, they collect the water and direct it out of the home. If the liner isn’t installed correctly, or if it shifts over time, water can accumulate, leading to mold growth.

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How Can I Tell Whether My Shower Is Waterproofed Enough? (What Are the Signs That It Isn’t?)

Figuring out whether your shower is properly waterproofed can be difficult because water damage isn’t always obvious. Here are some red flags to watch out for:

• The shower dries very slowly. You can look for water pooling around the drain or grout that stays dark and damp for a long time after the shower is used.

• Signs of mold and mildew. Mold can hide in the walls, but watch out for musty smells coming from around the shower. Mold or mildew that comes back quickly after a shower is cleaned can also be a sign of trouble.

• Problems with grout and caulk. Grout or caulk that constantly crumbles and splits can mean that water damage is making your tiles and shower joints shift.

You should also be on the lookout for signs of serious water damage like peeling paint, bulging walls, or a shower floor that feels spongy.

How Can I Boost or Reinforce the Waterproofing on My Shower?

Some small shower leaks can be easily fixed. If water is leaking out of your shower (rather than leaking through the tile or floor), this can be addressed by repairing the seal around the shower door or addressing problems with a shower curtain. An absorbent bath mat and good ventilation can also help address moisture problems in the bathroom.

Repairing any damaged caulk or grout in the shower can also boost the waterproofing. While constantly crumbling grout can be a sign of a bigger problem, maintaining these seals is important for keeping excessive amounts of water from leaking through the shower tiles.

Sometimes a shower insert system can help redirect water to the drain, but these don’t fully address the underlying problem. Unfortunately, if there are significant problems with waterproofing, you may need to consider installing a new one to avoid problems with mold or rot.