Sikalastic-590 Roof Waterproofing Coating 4kg / 20kg

Sikalastic-590 Roof Waterproofing Coating 4kg / 20kg

A one-component, water-based polyurethane-modified acrylic coating for seamless roof waterproofing. It combines elasticity, crack bridging, UV resistance and improved resistance to limited water ponding, with standard coating and reinforced membrane systems for new construction and refurbishment.

Product Features

• Good behaviour under limited water ponding; not a blanket claim for permanent immersion.
• Resistant to UV, yellowing and weathering.
• Highly elastic and crack-bridging.
• Ready-to-use, one-component water-based coating.
• Good adhesion on suitably prepared porous and non-porous substrates.
• Seamless and water-vapour-permeable membrane.
• White coating provides solar-reflective properties; published white-coating values do not apply to grey.

Specifications

• Brand: Sika
• Model: Sikalastic-590
• Composition: Polyurethane-modified acrylic dispersion
• Pack options: 4kg and 20kg plastic pails
• Listed colour options: Gray and Cool White
• Density: Approximately 1.32 kg/L at +30°C, EN ISO 2811-1
• Solid content: Approximately 63% by weight
• Shelf life: 12 months from production in properly stored original unopened, undamaged sealed packaging
• Storage: Dry conditions at +5°C to +30°C

Application

• Roof waterproofing in new construction and refurbishment.
• Roofs with complex geometry, many details or limited access.
• Life-cycle extension of failing roofs after appropriate assessment and preparation.
• White reflective roof coatings to help reduce solar heat gain.

Use reinforcement at movement-prone areas, irregular substrates, cracks, joints, seams and details. Sika's substrate instructions require reinforced systems on cementitious substrates and fully reinforced systems on suitable bituminous felt and coatings. Do not substitute a simple unreinforced coating where reinforcement is required.

How to Use

1. Assess the substrate and existing roof system. New concrete must cure for at least 28 days and have pull-off strength of at least 1.5 N/mm². Mechanically remove laitance and weak material, expose and repair defects, level surfaces and remove contaminants.
2. Ensure brick and stone joints are sound; secure tiles and slates and replace damaged sections. Abrade glazed tiles. Bituminous felt must be sound and bonded or fixed. Do not coat sticky or mobile bituminous surfaces, volatile mastics or old coal-tar coatings. Prepare metal to bright, sound surfaces and secure timber roof decks. Existing paint must be firmly adhered with oxidised layers removed.
3. Confirm substrate moisture below 6%, no rising moisture, and no surface water, moisture or condensation. Apply at air and substrate temperatures of +15°C to +35°C, relative humidity no more than 80%, and surface temperature at least 3°C above the dew point.
4. Stir for 1 minute with a drill and paddle until homogeneous. Avoid overmixing and air entrainment. On concrete, application during stable or falling temperatures helps reduce outgassing.
5. Prime with Sikalastic-590 diluted with 10% water at approximately 0.3 kg/m². Allow the primer to dry tack-free.
6. Where the unreinforced system is appropriate, apply two coats at approximately 0.5 kg/m² each, observing the drying periods.
7. For the reinforced system, apply an initial coat at approximately 0.3 kg/m², then an embedment coat at approximately 0.5 kg/m². The initial coat may be omitted only where the substrate is good and primer coverage and consumption are sufficient, as permitted by Sika.
8. Roll Sika-120 Reemat into the wet embedment coat, fully saturating it and removing air. Overlap reinforcement by at least 5cm and wet overlaps sufficiently to bond. Apply approximately 0.5 kg/m² wet-on-wet over the reinforcement.
9. After drying sufficiently for walking and observing the reinforced-system waiting period, sand off any projecting reinforcement fibres and apply the final coat at approximately 0.3–0.5 kg/m².
10. Use a short-pile roller and suitable brush for details. Airless spray is listed only for roof coating systems, with at least two spray-applied layers. Minimum equipment parameters: 220 bar pressure, 5.1 L/min output and 0.83mm nozzle.
11. Protect the fresh coating while curing. Clean tools with water immediately after use; hardened material requires mechanical removal.

What's in the Box

One pail of Sikalastic-590 in the selected 4kg or 20kg size and colour. Sika-120 Reemat reinforcement, repair products and application equipment are not listed as included.

Technical Information

• Tensile strength: Approximately 1.7 N/mm² for free film older than 7 days.
• Artificial weathering: Pass after 1000 hours UVA-340 exposure, with no cracking, blistering, delamination or chalking, ASTM G154.
• White coating only: Approximately 80% solar reflectance, 0.91 thermal emittance and solar reflectance index 100.9 at 12 W/m²K.
• Unreinforced system consumption: Diluted primer approximately 0.3 kg/m² plus two coats at approximately 0.5 kg/m² each.
• Reinforced system consumption: Diluted primer approximately 0.3 kg/m², optional initial coat approximately 0.3 kg/m² under Sika's stated conditions, embedment coat approximately 0.5 kg/m² with Sika-120 Reemat, wet-on-wet coat approximately 0.5 kg/m² and final coat 0.3–0.5 kg/m².
• Primer minimum drying time at 50% relative humidity: Approximately 2 hours at +20°C or 1 hour at +30°C.
• Unreinforced intercoat minimum waiting time at 50% relative humidity: Approximately 6 hours at +20°C or 4 hours at +30°C.
• Reinforced-system minimum waiting time before subsequent coating at 50% relative humidity: Approximately 24 hours at +20°C or 12 hours at +30°C. Follow the specified wet-on-wet reinforcement sequence separately.
• After thorough cleaning, Sika states the coating can be recoated with itself at any time.
• At +20°C and 50% relative humidity: Touch dry approximately 2 hours, rain resistant approximately 10 hours and fully cured approximately 4 days.
• At +30°C and 50% relative humidity: Touch dry approximately 1 hour, rain resistant approximately 6 hours and fully cured approximately 2 days.
• Drying and curing periods are approximate. Lower temperatures and higher humidity slow curing; warmer, drier conditions accelerate it.