Waterproof Drywall for Showers Done Right

Installing waterproof drywall in a shower area is critical to prevent leaks, water damage, and mold growth. With the right products and proper installation, you can create a water-resistant barrier that will keep your shower walls protected for years to come.

Benefits of Waterproof Drywall in Showers

Using waterproof drywall or cement board on shower walls provides several important advantages:

• Creates a water barrier to stop leaks from reaching the wall studs and subfloor.
• Prevents moisture damage, delamination, and mold growth on vulnerable shower walls.
• Allows you to use any waterproof tile, marble, or other surface materials.
• More durable than regular drywall in damp environments.
• Can be installed over existing shower surfaces like tile or fiberglass.

Unlike regular drywall, waterproof shower boards are designed to withstand direct water contact and humidity day after day. The coated glass mat or treated gypsum core resists moisture absorption.

Choosing the Right Waterproof Drywall

There are a few types of drywall suitable for showers:

Cement Board

Cement board, also called fiber cement board, is considered the most water-resistant choice. Brands like HardieBacker are made from Portland cement sandwiched between fibrous layers. It's durable, mold-proof, and recommended for shower walls and floors.

Cement board is unaffected by moisture and will not warp, swell, or deteriorate when exposed to water. It provides unmatched strength and tear resistance compared to other backer boards. The surface holds up well during tile installation and resists cracks or dents under heavy tile and stone.

On the downside, cement board is dense and more difficult to cut and install than drywall. It requires specialized cutting tools and screws. Thicker boards may be heavy and cumbersome to hang overhead one-handed. It's also one of the more expensive shower wall options.

Moisture-Resistant Drywall

Moisture-resistant or "greenboard" drywall has a gypsum core treated to repel water. Common brands include DensShield, Fiberock Aqua-Tough, Sheetrock Mold Tough, and Duraboard.

While not as indestructible as cement board, it resists humidity and splashes well. It's usually cheaper and easier to cut and install than cement board. Water-resistant drywall can be cut and screwed in place with standard drywall tools. Joints are finished using regular drywall joint compound and tape.

On the negative side, moisture-resistant drywall is not designed for direct water contact. The facers and core still contain paper, so prolonged moisture exposure can cause swelling, disintegration, and mold growth. It's sufficient for walls that receive occasional splashes or condensation.

When selecting a product, consider the thickness (1/2" or 5/8"), waterproof coatings used, mold resistance rating, and manufacturer warranties.

Prep Work Before Installation

Proper planning and prep work are key to successful waterproof drywall installation in showers:

• Remove existing shower walls down to the studs if needed.
• Address any leaks, water damage, or mold on walls or around fixtures.
• Install backing boards to provide support for shower heads, shelves, soap dishes, etc.
• Plan the board layout to minimize seams and complex cuts.

Make sure the framing is moisture-resistant and meets local building codes. Repair rotted or damaged wood. A clean, stable structure is vital.

One of the most important prep steps is sealing the entire shower area. Apply a waterproofing membrane or liquid sealant to the walls and floor framing before installing any backer board. RedGard, Laticrete Hydro Ban, and Mapei AquaDefense are popular options. Waterproofing behind boards is crucial to direct water downward and prevent wicking up into the walls.

Also check that the drainage slope of the mud base is correct, with a minimum 1/4" per foot pitch towards the drain. Adjust as needed to prevent standing water.

Step-by-Step Installation Guide

Follow these key steps to properly hang and finish waterproof drywall in showers:

1. Cut Boards to Size

Measure and mark the shower area. Cut boards to fit using a utility knife and straightedge for drywall, or a carbide-tipped scoring tool and snapper for cement boards. Make plumbing cutouts as needed.

Avoid unnecessary seams by using the largest boards possible. Butt boards tightly, though creating slight gaps is okay since joints will be taped. Stagger seams between rows.

2. Fasten Boards to Studs

Attach boards using corrosion-resistant screws like hot-dipped galvanized or ceramic-coated. Space screws 8-10 inches apart in the field and closer on edges and ends. Sink screws just below the surface.

Make sure boards are fastened firmly at studs. Add backer boards behind joints for double support. Apply silicone or construction adhesive between boards and framing for extra bonding.

3. Tape and Mud Seams

Fill gaps between boards with waterproof joint compound. Then embed alkali-resistant fiberglass tape and apply 2-3 coats of compound to feather and smooth seams.

Allow proper drying time between coats. Be sure to coat screw heads and corners thoroughly. Avoid excess buildup that could telegraph through tile.

4. Seal Corners and Edges

Waterproof all joints with flexible 100% silicone caulk. Apply a smooth bead and tool into corners and along board edges. Extend caulking 2-3 inches past shower boundaries to seal perimeter edges.

Let the caulk fully cure for 24-48 hours before applying any membranes or tiles. Curing prevents the sealant from being compromised.

5. Apply Waterproofing Finish

Roll or trowel on a waterproofing paint or membrane per product instructions. RedGard and Laticrete Hydro Ban are two popular liquid-applied membranes. Allow proper cure time.

The entire surface should be coated evenly, including over joints. Multiple coats may be needed for effective waterproofing on seams or repairs.

6. Install Tile Backer Board

If tiling, attach cement board or a second layer of drywall over the waterproofed surface to create a durable underlayment for tiles.

Use a latex-modified mortar for bonding. Make sure backer boards are firmly embedded. Follow manufacturer guidelines for any floor-wall transition boards.

Avoiding mistakes with water barriers is vital. Take time to prepare surfaces, use compatible materials, and test for leaks. With careful installation, waterproof drywall will protect your shower for the long haul.

While waterproof drywall installation may seem straightforward, there are some key mistakes to avoid:

• Not adequately sealing behind boards - Gaps in the water barrier allow moisture intrusion.
• Improper fastening - Loose boards or incorrect screws lead to movement and cracks.
• Poor corner treatment - Inside corners are prone to leaks without ample caulk and membrane.
• Incomplete joint sealing - Any untreated seams or damage can compromise waterproofing.
• Not allowing proper cure times - Rushing the job leads to weak bonds and flaws.
• No leak testing - Sprinkle testing before tiling ensures waterproofing integrity.

Careful installation and sealing are required to prevent thousands in shower damage. Take a methodical approach and don't cut corners on any steps.