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How do you seal the bottom of a shower tray?

Published in Shower Tray Sealing 4 mins read

To seal the bottom of a shower tray effectively, you primarily focus on applying a waterproof seal around its perimeter where it meets the walls and, if applicable, the floor, as well as sealing the drain area. This prevents water from escaping and causing damage beneath the tray or to the surrounding structure.

Preparing for Sealing

Before applying any sealant, proper preparation is crucial for a lasting, watertight bond.

  • Clean and Dry Surfaces: Ensure the shower tray and the adjacent wall or floor surfaces are completely clean, dry, and free from any dust, dirt, grease, soap scum, or old sealant residue. Use a suitable cleaner and allow ample time for the area to dry thoroughly. Any moisture can prevent the sealant from adhering properly.
  • Remove Old Sealant: If resealing an existing tray, meticulously remove all traces of old silicone or caulk using a sealant remover tool or a sharp knife, taking care not to scratch the tray or tiles.
  • Masking (Optional but Recommended): For clean lines, apply masking tape along the edges of the tray and the wall/floor, leaving a gap equivalent to the desired width of your sealant bead.

Choosing the Right Sealant

Selecting an appropriate sealant is vital for durability and mold resistance in a wet environment.

  • Silicone Sealant: Opt for a high-quality, waterproof silicone sealant.
  • Mold Resistant: Choose a sealant specifically labeled as mold-resistant or anti-fungal to prevent unsightly black mold growth common in bathrooms.
  • Color: Select a color that matches your shower tray or tiles for a seamless look.

Applying the Sealant to the Perimeter

This is the primary method for sealing the visible bottom edges of the shower tray.

Using a caulking gun makes the application process significantly easier and more precise.

  1. Prepare the Caulking Gun: Insert the sealant tube into the caulking gun. Cut the nozzle of the sealant tube at a 45-degree angle, making the opening slightly smaller than the desired bead width.
  2. Steady Application: With a steady grip, position the nozzle at the beginning of the joint where the shower tray meets the wall or floor.
  3. Release Evenly: Begin to release the sealant by gently squeezing the trigger of the caulking gun, moving it along the joint in one continuous, smooth motion. The goal is to create an even bead of sealant along the entire length of the joint.
  4. Control Pressure: It is important not to apply too much pressure as this may cause an excessive amount of sealant to be expelled from the tube, leading to a sealant mess and wastage. Aim for a consistent, moderate flow.
  5. Smooth the Bead: Immediately after applying a section of sealant, smooth it out. This can be done using a specialized sealant profiling tool, a wet finger (wearing gloves), or a moistened plastic spoon. This step pushes the sealant into the joint, ensures good adhesion, and creates a neat finish. Remove any excess sealant as you go.

Best Practices for Sealing

  • Work in Sections: For larger trays, work on one side at a time to ensure you can smooth the sealant before it begins to cure.
  • Corners: Pay extra attention to corners, ensuring they are fully filled and sealed.
  • Remove Masking Tape: If used, carefully remove the masking tape immediately after smoothing the sealant, before it starts to skin over. Pull the tape away at a 45-degree angle for a sharp edge.

Sealing the Drain Area

While the perimeter is critical, sealing the drain assembly (waste trap) at the bottom of the tray is also essential to prevent leaks. This typically occurs during the installation of the tray, but it's part of the "bottom" seal.

  • Waste Trap Assembly: Apply a bead of plumber's putty or a silicone sealant directly under the flange of the drain on the tray's surface before tightening the waste trap assembly from underneath. This creates a watertight seal between the drain opening and the waste fitting.
  • Gaskets: Ensure any rubber or foam gaskets provided with the drain assembly are correctly positioned and compressed when fitting the waste.

Curing Time

Allow the sealant to cure completely before using the shower. The drying time can vary depending on the product and humidity levels, but typically ranges from 12 to 24 hours. Check the manufacturer's instructions on the sealant tube for precise curing times.