06. Wet Areas (Bathrooms / Balconies / Kitchens / Refuge Slabs)

06. Wet Areas (Bathrooms / Balconies / Kitchens / Refuge Slabs)

System Manual
01. BOQ with Specs, Checklists_Bathrooms.xlsx

1. Introduction

Wet areas (bathrooms, balconies, kitchens, refuge slabs) are high-risk leak zones with continuous or frequent water exposure, chemical cleaning loads and many penetrations (drains, pipes, channels). Correct substrate prep, detail work (upstands, fillets, pipe treatment) and a proven membrane system are essential. Wet areas are the most critical small-area waterproofing applications — they need watertight, durable, tile-compatible systems that survive constant wetting, cleaning chemicals and local movements.

2. Typical exposures

  • Continuous/periodic water contact (showers, cleaning).
  • Thermal cycling and local movement (tiles, grout).
  • Detergents/chemicals (household cleaners).
  • Frequent penetrations (drains, sanitary pipes).
  • Localized foot traffic/fixtures.

3. System goals / functional requirements

  • Seamless, continuous barrier at floor & walls.
  • Compatibility with tile adhesives & grout.
  • Ability to bridge minor movement/cracks.
  • Robust detailing at drains, pipe penetrations and upstands.
  • Ease of inspection & pond-testing prior to tiling.

4. Technologies we recommend

  • 2K elastomeric cementitious membranes (recommended choice).
  • 1K cementitious membrane
  • SBR-latex modified mortar / SBR primer (as primer or admixture).
  • 2K PU (liquid applied) for specialized details / penetrations (pipe penetrations often use 2K PU + geotextile).

5. Quick tech comparison (which to choose)

Tech
When to use
Pros
Cons
2K Elastomeric Cementitious
Default for bathrooms, balconies, kitchens, refuge slabs
Potable-water safe, good elasticity (≥40%), tile-friendly, economical
Less elongation vs PU, needs screed protection
1K Cementitious
Low-cost small jobs (non-critical)
Simple, low capex
Lower flexibility — avoid where movement expected
SBR latex (primer/admixture)
As primer, additive to mortar or thin-bed tile adhesive
Improves adhesion, slightly increases flexibility
Not a standalone membrane for heavy wet areas
2K PU liquid
Pipe penetrations, special cases needing high chemical or movement resistance
Seamless, superior crack-bridging, good for verticals & penetrations
Costlier; applicator skill & cure-time important

6. Substrate & system pre-requisites

  • Concrete slab: Strength ≥ M20 recommended; surface sound and stable.
  • Moisture: Check residual moisture; many cementitious systems accept damp but follow product limits
  • Typical safe working guideline: substrate moisture controlled and within manufacturer limits (measure & record).
  • Sleeves & sleeves removal: Leave sleeves during casting (typical Ø110 mm), remove during deshuttering, pack annulus with polymer-modified non-shrink grout.
  • Upstands: Provide 150 mm concrete upstand above FFL where specified; micro-concrete upstands 35–50 mm for door thresholds.

7. Standard protocol / method

  1. Surface prep: Mechanical grinding to remove laitance; vacuum cleaning. Repair honeycombs, blow dust free.
  2. Pipe & sleeve prep: Coat drain pipes with epoxy primer/sand; install hydrophilic waterstop around pipe before casting if required. After cure, pack annulus with polymer-modified grout.
  3. Fillet (watta): Provide 20×20 mm fillet at floor–wall junctions or use 50×50 mm treatment at critical junctions.
  4. Crack treatment: Open cracks >0.5 mm to 10×10 mm V groove; grout with pre-packed polymer-modified non-shrink grout; reinforce with geotextile hatched in first coat.
  5. Membrane application: Apply first coat of elastomeric cementitious membrane (brush/roller). Lay geotextile at cracks/penetrations in wet coat. After initial set, apply second coat crosswise. Typical DFT: 1.0 mm over normal areas; 2.5 mm over cracks and penetrations
  6. Upstand & verticals: Apply a third coat on verticals/upstands 72 hrs prior to tiling if required.
  7. Pond testing: Pre-pond test for 24 hrs (pre-membrane) and final pond test for 72 hours after membrane application & curing. Only after successful pond test proceed with screed & tile works.
  8. Protection & screed: Lay protective screed (min 50 mm typically) with slope 1:100 toward drain; moist cure screed for 7 days.

8. Common mistakes to avoid (practical notes)

5. Video Masterclass

SpecX Masterclass: Wet Areas Waterproofing — Coming Soon

Disclaimer

SpecX is an industry initiative & a neutral resource, compiled from industry references and best practices. It is not brand-specific. Always cross-check with project requirements and local codes before finalizing specifications.

  • Applying membrane on dirty or uncured concrete (leads to adhesion failures).
  • Skipping geotextile at cracks/penetrations.
  • Not doing pond test or doing too early.
  • Tiling before screed & membrane adequately cured.
  • Using cementitious membranes on heavy-movement podiums or car-deck-like loads.