Sika Sikalastic 680
Sika Sikalastic 680
Sikalastic 680 — Single Component Polyurethane Waterproofing Membrane
Sikalastic®-680 is a single-component, highly elastic polyurethane liquid-applied waterproofing membrane for concrete structures. It forms a continuous, seamless waterproof layer and must be covered by protective toppings (screed, tiles, or ballast). Commonly known in Hong Kong as "rooftop waterproofing black glue" (天台防水黑膠).
Key Features
- Single component — ready to use, no mixing required
- High elasticity — elongation at break > 500%
- Quick drying — tack free in approximately 4 hours (25°C / 75% RH)
- Excellent adhesion to concrete, render, and masonry (> 1 MPa)
- Good impact and abrasion resistance
- Low odour, non-toxic
- Low temperature flexibility
- Multiple application methods: brush, roller, trowel, squeegee, or airless spray
Applications
- Roofs, podiums, balconies (covered by protective toppings)
- Bathrooms, pools, tanks, green roofs, and planters
- External walls, basements, and foundations
- As water barrier under plasters, screeds, or tiles
Important: Sikalastic®-680 is designed for non-exposed use. A protective covering layer must be applied over the finished membrane.
Technical Specifications
| Property | Value |
|---|---|
| Chemical Base | Polyurethane |
| Components | Single component, ready to use |
| Colour | Black, grey |
| Density | ~1.5 kg/L (± 0.05) |
| Shore A Hardness | 60 (± 5) |
| Tensile Strength | ~2 MPa |
| Elongation at Break | > 500% |
| Tensile Adhesion Strength | > 1 MPa |
| Tear Strength | ~15 N/mm |
| Yield (Standard) | ~2.0 kg/m² (~1.3 mm wet film), one or more coats |
| Yield (Reinforced) | ~2.5 kg/m² (~1.6–1.7 mm wet film), with Sika® Glass Fabric |
| Tack Free Time | ~4 hours (25°C, 75% RH) |
| Ambient Temperature | +5°C to +40°C |
| VOC Content | ≤ 250 gm/L (HK Air Pollution Control — Roof coatings, non-exposed) |
| Packaging | 20 kg pail |
| Shelf Life | 9 months from date of production |
| Storage | Unopened, cool and dry, away from sunlight and frost |
Product Comparison
| Product | Type | Exposed Use | Elasticity | Best For |
|---|---|---|---|---|
| Sikalastic 680 | Polyurethane | Must be covered | High (> 500%) | Roofs / basements / pools — under tiles or screed |
| SikaFill C | Acrylic | Can be exposed | High | Village rooftops / walls — economical choice |
| Nitoproof 600PF | Polyurethane | Must be covered | High | Large projects — requires protective screed |
| Hyperdesmo Classic | Polyurethane | Can be exposed | Very high | Premium projects — 30-year brand |
FAQ
Can Sikalastic 680 be left exposed?
No. According to the product data sheet, Sikalastic®-680 is designed for non-exposed applications and must be covered by a protective layer such as screed, tiles, or ballast. For exposed waterproofing solutions, consider SikaFill C (acrylic) or Hyperdesmo Classic (exposed-grade polyurethane).
How long before a flood test can be carried out?
Allow at least 3 days of drying at 25°C and 75% relative humidity before flood testing. In cooler or more humid conditions, drying time will be longer and the waiting period should be extended accordingly.
