Shower Waterproofing: Getting It Right
Waterproofing a shower correctly is essential to preventing leaks, mould growth, and structural damage. In Adelaide, where building inspectors report that shower leaks account for over 40% of residential water damage claims, the importance of proper waterproofing cannot be overstated. This guide walks through the professional shower waterproofing process used by licensed Adelaide waterproofers.
While this guide explains the process, shower waterproofing is regulated building work in South Australia that must be carried out by a licensed contractor. Use our Find a Waterproofer tool to find licensed shower waterproofing specialists in your area.
Step 1: Substrate Preparation
Proper substrate preparation is the foundation of a successful shower waterproofing system. The shower floor must have a minimum fall of 1:60 toward the drain to prevent water pooling. The screed surface must be clean, dry, and free from dust, oil, curing compounds, and loose material. Any cracks wider than 0.5mm must be filled with a flexible filler, and the substrate must be allowed to cure for a minimum of 7 days if it is new.
In renovation projects, all existing tiles, adhesive, and membrane material must be removed to expose a clean substrate. This is often the most labour-intensive part of the job, especially in older Adelaide homes where multiple layers of materials may have been applied over the decades.
Step 2: Priming
A primer coat is applied to the prepared substrate to improve adhesion between the substrate and the waterproofing membrane. The primer type must be compatible with both the substrate and the membrane system — using incompatible products can cause delamination. Most Adelaide waterproofers use the primer recommended by the membrane manufacturer to ensure system compatibility.
The primer is applied by brush or roller and must be allowed to dry before membrane application. Drying time varies from 1 to 4 hours depending on the product and Adelaide's ambient conditions.
Step 3: Membrane Application
Reinforcing tape is applied to all internal corners, wall-floor junctions, and around penetrations (drain, taps, shower arm) while the first coat of membrane is still wet. This tape bridges movement joints and reinforces the membrane at its most vulnerable points. The first coat of liquid membrane is then applied to the entire shower area — floor, walls to 1800mm minimum, and the hob.
After the first coat has dried (typically 4-12 hours), a second coat is applied at right angles to the first to ensure complete coverage. The total dry film thickness must meet the manufacturer's specification, typically 1.0mm to 1.5mm. For more detail on membrane products, see our shower membrane guide and our shower waterproofing service page.
Step 4: Flood Testing and Certification
Once the membrane has fully cured (24-48 hours), a flood test is mandatory under AS 3740. The shower floor is dammed and filled with water to a minimum depth of 25mm. The water level is marked and left for a minimum of 24 hours. If the water level has not dropped and no moisture is visible on the underside (checked from below if accessible), the waterproofing has passed.
The waterproofer then issues a compliance certificate documenting the membrane system used, application details, and flood test results. This certificate should be retained for building compliance and insurance purposes. Learn about the full standards in our bathroom waterproofing standards article.