WATERPROOFING SYSTEMS: WHAT’S THE DIFFERENCE?

cementitious-vs-acrylic-vs-polyurethane-waterproofing-EN

Short answer: Cementitious (Cement-based waterproofing) is suitable for indoor areas that are constantly damp, Acrylic is ideal for general outdoor applications seeking cost-effectiveness, whereas Polyurethane Hybrid is best for applications requiring maximum flexibility and durability.

Choosing the wrong type of waterproofing material is one of the top causes of recurring water leakage problems, despite the investment made, because each type of waterproofing is designed for different operating conditions. This article will explain the working principles, strengths, limitations, and appropriate applications of these three main types of waterproofing to ensure the right selection for your project site.

1. Cementitious ( Cement-based waterproofing )

This type of waterproofing has cement as its main ingredient, mixed with sand, polymer additives to aid adhesion and increase flexibility. It may come in the form of a 1-part cement powder mixed with water (such as CEMFLEX 1K or KRYSTALSEAL) or a 2-part cement powder mixed with liquid polymer (such as CEMFLEX-HP). Once dry, it forms a waterproof layer that seamlessly integrates with the concrete surface.

Key Features

⬣ Excellent adhesion to concrete and plaster surfaces

⬣ Highly resistant to ponding water and withstands water pressure well, both positive side and negative side (such as ELASTOCEM or ELASTOCEM-300)

⬣ Can be applied on damp surfaces without waiting for them to be completely dry

⬣ Tiles can be laid directly over it without the need for an additional protective layer

⬣ Safe for use with drinking water tanks

Limitations

⬣ Flexibility ranges from low to moderate depending on the formula. All-powder formulas are relatively rigid and do not accommodate moving cracks, whereas liquid-polymer blended formulas offer better flexibility.

⬣ Due to the alkalinity of cement, it may chemically react with certain materials, and proper curing methods must be observed.

⬣ Not suitable for surfaces subject to movement or continuously expanding cracks.

Ideal for: Bathrooms, swimming pools, water tanks, basements, catch pits, and constantly damp areas where tiles will be laid over them.

Cemflex-HP

Semi Flexible Cementitious Waterproofing Slurry

Cemflex-1K

One Part Cementitious Waterproofing Slurry

Elastocem

Flexible Cementitious Waterproofing Membrane

Elastocem-300

Highly Flexible Cementitious Waterproofing Membrane

2. Acrylic

Liquid waterproofing primarily composed of acrylic polymer. When dry, it forms a continuous, seamless thin rubber film (elastomeric membrane) that covers the entire surface like a raincoat (such as ACRYLIC ROOFKOTE).

Key Features

⬣ Good flexibility, capable of bridging hairline cracks

⬣ Highly resistant to sun and rain, suitable for outdoor applications

⬣ Easy to apply using a roller or brush, requires no specialized skills

⬣ Cost-effective, making it a popular choice for general applications

Limitations

⬣ Must be applied on completely dry surfaces

⬣ Can withstand ponding water for a certain period, but because the polymer film is prone to blistering, leveling the surface beforehand is recommended for areas prone to water accumulation

⬣ Should be applied in multiple coats as specified by the manufacturer to achieve sufficient film thickness

Ideal for: General rooftop decks, concrete roofs, exterior walls, and outdoor areas without water pooling and minimal heavy traffic.

Acrylic Roofkote

Elastomeric Acrylic Waterproof Coating

3. Polyurethane Hybrid

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Waterproofing coating resulting from a blend of polyurethane and acrylic that undergoes a chemical reaction to form a cross-linking molecular structure, creating a tough, dense, and highly elastic rubber film. Generally water-based formulas (such as PU ROOFKOTE or PU ROOFKOTE-ES).

Key Features

⬣ Extremely high elongation, clearly superior to acrylic in accommodating cracks and structural movement

⬣ Resistant to sunlight and UV radiation (especially aliphatic formulations), abrasion, and heavy duty use

⬣ Tough, strong, and durable film

⬣ Excellent resistance to standing water with a long service life

Limitations

⬣ Higher price compared to standard acrylic and cementitious types

⬣ Requires meticulous surface preparation; the surface must be completely dry, as trapped moisture will cause blistering

⬣ Should be applied by experienced technicians to ensure consistent film thickness

Ideal for: Rooftops with foot traffic, balconies, and surfaces subject to frequent movement or constant exposure to intense sunlight

PU Roofkote

สีโพลียูรีเทนทากันซึมสูตรน้ำ

PU Roofkote-ES

สีโพลียูรีเทนยืดหยุ่นพิเศษ
ทากันซึม สะท้อนความร้อน

Visual Comparison: Choosing the Right Waterproofing Material for Your Project

Tap or click the topics below to compare key properties and limitations across all 3 waterproofing types.

📊 Topic: Flexibility

How to Choose the Right One for Your Project
Before making a decision, you should ask yourself four questions: Is the area indoor or outdoor? Is there standing water? Is there foot traffic or weight loading? And how much does the structure move?

Easy to Remember:

⬣ Indoor, damp, standing water → Cementitious

⬣ Outdoor, general application, cost-effective → Acrylic

⬣ Heavy sun exposure, high movement, needs long durability → Polyurethane Hybrid

Precautions Applicable to All Types

1. Proper surface preparation: The surface must be clean, sound, and free from dust, oil, and loose debris, because even the best waterproofing material will fail if it does not adhere well to the substrate.

2. Follow the manufacturer’s specified thickness: Applying it too thin to save costs is the primary cause of recurring leaks.

3. Pay attention to critical points: Such as wall corners, floor-to-wall joints, around pipes, and floor drains, which should be reinforced with fiberglass mesh or reinforcing tape.

4. Test before finishing: Especially for bathrooms and rooftops, a water ponding test should be conducted for at least 24–48 hours before laying tiles or covering the surface.

5. Check actual specifications from the manufacturer: Properties may vary by brand and formula; always read the Technical Data Sheet (TDS) before application.

1. Cementitious ( Cement-based waterproofing )

2. Acrylic

3. Polyurethane Hybrid

Visual Comparison: Choosing the Right Waterproofing Material for Your Project

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