10 Tips for Waterproofing Your Bathroom

Waterproofing Bathtub with Caulk

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Developing an efficient, workable system of moisture protection the cornerstone of any successful bathroom remodel project. How your bathroom manages the considerable amount of moisture it produces is the very pivot point between a bathroom remodel that stays clean and in great condition for years and a bathroom that slowly decays and falls victim to mold and mildew.

Use Waterproof Building Materials

Organic building materials that are sometimes used in a bathroom remodel include wood, plant fibers such as cotton or jute, paper, or bamboo. Inorganic materials are those such as natural stone, metal, plastic, ceramic and porcelain, and manufactured stone.

Inorganic materials will not rot or decay, and they tend to resist mold and mildew better than organic materials. For example, you may want to use PVC baseboards instead of MDF or solid wood baseboards. Porcelain and tile work well for walls and floors. Solid surface and quartz countertops are waterproof but solid wood is not. Even the MDF base of laminate countertops is not waterproof.

Create a Watertight Baseboard System

Baseboards are installed at the junction between the bathroom floor and the walls. Tight baseboards caulked at top and bottom prevent water from seeping into the wall. A flexible thermoplastic vinyl wall base helps form a tight seal without the need for caulking.

Caulk All Cracks and Holes

Silicone-based bathroom-grade caulk is indispensable with any bathroom remodel. Use this caulk for bathrooms, showers, sinks, and backsplashes. Apply liberally into all cracks and holes but avoid seepage to the side by using painter's tape on all areas that will not be caulked. To apply, wear a latex glove and dip your finger into water, then draw your finger through the caulk to press it into the crack and form a smooth shape.

Install a Waterproof Floor

Your choice of bathroom flooring falls under the recommendation to favor inorganic over organic building materials. Hardwood or engineered wood flooring are poor choices for bathrooms since they tend to easily soak up water, swelling up and refusing to contract back to their previous state. Use ceramic tile, porcelain tile, luxury vinyl tile, sheet vinyl, vinyl tile, or natural or manufactured stone for the floor.

Install a Tile Wainscot or Wall

To create walls that are perfectly waterproof, tile over them. Ceramic and porcelain tile have long been used for shower and bathtub surround walls. In the same sense, this type of tiled wall system can be extended into the rest of the room. Sometimes the tile runs from floor to ceiling, while in other applications the tile stops at about 42 inches above the floor, as a kind of waterproof wainscot.

Build or Install a Watertight Shower or Tub

A shower, bathtub, or shower/bathtub combination is almost like a room within a room. The bathroom itself is kept far drier if you keep this smaller enclosure watertight. Tilers building a custom shower from scratch will use a waterproof polymer mat under the tile. If installing a pre-fabricated shower or bathtub, surround walls will lock into the shower pan or bathtub. Joints are either caulked or, in some cases, are left open. Caulk-free joints are meant for the water to drain back into the bathtub or shower pan.

Provide Access to the Plumbing

While not mandatory, it is always helpful, if possible, to provide access to the bathtub or shower plumbing from the rear via a service panel. If the room on the other side permits, an opening can be created in the wall to allow the water supply lines to be observed and repaired from the back. It is far easier to work on plumbing this way than ripping out the tile from the front.

Install an Exhaust Fan and Heat Source

Install a high-capacity bathroom exhaust fan as one method of expelling moisture-laden air from the room. By building code, bathroom fans must expel a minimum of 50 cubic feet per minute (cfm) intermittent and 20 cfm continuous. Standalone infrared heat bulb units can aid in burning off moisture in bathrooms that have condensation problems.

Use Higher Sheen Paint

Flat or matte sheen interior paint on the bathroom walls tends to streak and stain. Use glossier paints to ward off the inevitable splashes from the bathing facilities and from condensation. Satin, eggshell, and semi-gloss paints are bathroom favorites for their ease of application and durability.

Maintain Your Waterproofed Bathroom

After the remodel, keep your bathroom in good condition by managing moisture by:

  • Using bath mats
  • Keeping cracks caulked
  • Sealing tile seams
  • Using tightly fitting shower curtains
  • Mopping up spilled water
  • Painting walls on a regular basis
  • Fixing gapped floorboards