1. Introduction
Cementitious membranes are polymer-modified cement-based coatings, supplied as 1K (powder only) or 2K (powder + polymer liquid) systems. They are brush/roller-applied, forming a dense, continuous barrier against water ingress.
They are commodity-type products, widely used due to their:
- Low cost
- Simple application
- Compatibility with tile adhesives/screeds
However, they have limited flexibility compared to polyurethane or HDPE membranes, making them more suitable for swimming pools, water tanks, bathrooms, balconies, and light-duty podiums, rather than highly stressed structural decks.
2. Advantages
- Cost-effective and widely available.
- Easy brush/roller application; no heavy machinery required.
- Good adhesion to damp concrete substrates.
- Potable water safe (suitable for tanks & pools).
- Compatible with tile adhesives and epoxy grouts.
3. Limitations
- Limited elongation: 40–150%, depending on grade.
- Not suitable for heavy dynamic movements (e.g., podiums, car decks).
- Requires protective screed; not trafficable in exposed condition.
- Risk of shrinkage cracks if applied too thick in one layer.
- Cannot bridge wide structural cracks (>0.5 mm).
4. Types of Cementitious Membranes
Type | Components | Elongation Range | Application Method | Use Case |
2K Cementitious Membrane (Std.) | Powder + liquid polymer | 40–70% | Brush / Roller | Bathrooms, Balconies, Swimming pools, Kitchens, overhead/UG tanks, balconies |
2K High-Performance Cementitious | Powder + polymer (elastomer-rich) | 120–150% | Brush / Roller | Demanding pools; light structural movement areas |
1K Cementitious Membrane | Single pack powder (add water) | ~30–50% | Brush / Roller | Small tanks, Swimming Pools |
6. Application Methodology
- Substrate Preparation → Clean, SSD (saturated surface dry), repair cracks >0.5 mm with repair mortar.
- Mixing → (1K: add water to powder) / (2K: mix liquid polymer into powder, mechanical mixing only).
- First Coat → Apply by brush in single direction.
- Second Coat → Cross-direction application after 4–6 hrs, ensuring total thickness ≥2 mm.
- Reinforcement → Geotextile mesh at corners/junctions.
- Curing → Moist cure for 72 hrs before pond test.
- Protection → Apply screed or tiles before final use.
5. Video Masterclass
SpecX Masterclass: Cementitious Membrane — 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.