DIY BLOG
DIY Guide: How to Waterproof Your Shower Like a Pro
How to Waterproof a Shower
Skipping waterproofing risks leaks, mould, and expensive repairs. Follow this practical, step‑by‑step guide to keep water where it belongs — inside the shower.
Why Waterproofing Matters
Bathrooms are the most moisture‑prone spaces in a home. Tiny leaks behind tile can seep into walls and floors, causing structural damage. A proper membrane system creates a continuous barrier so moisture can’t escape.
What You’ll Need
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Roller, trowel, sheet membrane, tape, silicone.
- Waterproofing membrane (liquid or sheet)
- Waterproofing tape & preformed corner seals
- Cement tile backer board & corrosion‑resistant screws
- Silicone sealant
- Thin‑set mortar (for sheet membranes)
- Notched trowel or roller/brush; utility knife & scissors
- Bucket, sponge, clean cloths
Step‑by‑Step
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Prepare the Surface
Strip old tiles or finishes. Install cement backer board on walls (never standard drywall). Ensure surfaces are clean, flat, dust‑free, and dry.
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Seal Joints and Corners
Embed waterproofing tape over all seams where walls meet and where walls meet the floor. Add preformed corner seals. Silicone any screw heads and tiny gaps.
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Apply the Waterproofing Membrane
Liquid membrane: Roll/brush on thin, even coats (2–3 total). Respect the manufacturer’s dry times between coats. Extend beyond the shower opening a few centimetres.
Sheet membrane: Trowel on thin‑set, press sheets in, and roll smooth. Overlap seams by at least 50 mm (2″) and band with waterproofing tape.
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Waterproof the Shower Pan
Confirm the pan is pre‑sloped toward the drain. Run the membrane across the floor and up the walls 150–200 mm (6–8″). Reinforce around the drain and any penetrations.
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Final Checks & Flood Test
Allow the system to fully cure per the product datasheet. Plug the drain and fill the base with water. After 24 hours, the water level should be unchanged. If it dropped, locate and fix the leak, then retest.
Pro Tips
- Always overlap seams; water will find the smallest gap.
- Use mesh tape on backer‑board joints before banding with membrane tape.
- Plan your tile layout so you don’t puncture fresh membrane unnecessarily.
- Ventilation matters — run an extractor fan during and after showers.
- Keep receipts and product datasheets for future maintenance or resale disclosures.
FAQ
Liquid vs. sheet membrane — which is better?
Sheet membranes offer consistent thickness and reliable seams; liquids are flexible and easier for complex shapes. Both work when installed per the instructions.
Can I waterproof over painted drywall?
No. Replace with cement backer board or an approved substrate for wet areas.
Do I still need a vapour barrier?
Don’t double up. If using a surface membrane, skip a separate plastic sheet behind the board unless the manufacturer specifies otherwise.