Liquid Applied Waterproofing Membrane - Sikalastic®-641 Lo-VOC

Single component low-VOC, low odor saturating resin for Sikalastic® RoofPro roofing and waterproofing systems

Sikalastic®-641 Lo-VOC is a cold applied, highly elastic, aliphatic, single component, low-odor, low-VOC moisture-triggered polyurethane resin designed for easy application as part of Sikalastic® RoofPro roofing systems.

• Proven technology with over 30 year track record
• Single component - no mixing and ready to use
• Fully reinforced with highly conformable Sika Reemat or Sika® Fleece
• Moisture triggered chemistry that is rapidly weatherproof after application
• Low VOC formula - low Odor
• Highly elastic and crack bridging
• Seamless and fully adhered
• Vapor permeable
• UV resistant and non-yellowing
• Abrasion and chemical resistant
• Adheres to most common construction materials when suitable primer is used

Usage

• Embedment and top resin for Sikalastic® RoofPro systems reinforced with Sika Reemat
• Saturating resin for Sikalastic® RoofPro systems reinforced with Sika Fleece
• Typically applied in Sikalastic® RoofPro Direct, Plaza, and Vegetated systems for both new construction and refurbishment

Advantages

• Proven technology with over 30 year track record
• Single component - no mixing and ready to use
• Fully reinforced with highly conformable Sika Reemat or Sika® Fleece
• Moisture triggered chemistry that is rapidly weatherproof after application
• Low VOC formula - low Odor
• Highly elastic and crack bridging
• Seamless and fully adhered
• Vapor permeable
• UV resistant and non-yellowing
• Abrasion and chemical resistant
• Adheres to most common construction materials when suitable primer is used

Packaging

5 gal. (19 L) pail

Color

White, Pearl Gray, Steel Gray, Mushroom, Copper Green; Custom colors available with minimum order quantity

Product Details

Sustainability / Certifications / Approvals

Environmental Product Declaration (EPD) - Cradle-to-Grave

• FM Approval Standard 4470 for Class 1 Roof Covers
• Meets ASTM D7311-07: Standard Specification for Liquid-Applied, Single-Pack, Moisture-Triggered, Aliphatic Polyurethane Roofing Membrane

Product Information

Moisture triggered Polyurethane

15 months in original, unopened container.

Store dry between 35 °F and 77 °F (2-25 °C). Condition material to 50-77 °F (10-25 °C) before using for ease of application

11.9 lb./gal. (1.4 kg/cm³)

Technical Information

-22-176 °F (-30-80 °C) intermittent

Most common roofing contaminants, oils, grease, dilute acids and bases

Application

Application Information

41 °F (5 °C) min. / 95 °F (35 °C) max.

80 % R.H. max.

Beware of condensation.
The substrate and uncured coating must be ≥ 5 °F (3 °C) above dew point.

41 °F (5 °C) min. / 140°F (60°C) max.

4 % moisture content Test method: Sika®-Tramex meter
No rising moisture according to ASTM (Polyethylene-sheet)

Sikalastic®-641 Lo-VOC is designed for fast curing. High temperatures combined with high air humidity will increase the curing process. Thus, material inopened containers should be applied immediately. In opened containers, the material will form a film after 1-2 hours approx. ( at 75 °F (24 °C) and 50 % R.H.)

Application Steps

All substrate surfaces shall be clean, dry and sound. Acceptable substrates include: sound concrete and cementitious screed, metals, wood, modified bitumen, mineralized felt, EPDM, hypalon, TPO, sprayed polyurethane foam, brick and stone, slate and tile, and existing liquid applied membranes. Reference separate System Data Sheet for specific surface preparation requirements.

Primer
Apply primer of a type suitable for the substrate. Allow primer to cure completely before applying Sikalastic®-641 Lo-VOC resin. Reference separate System Data Sheet for specific primer recommendations.

No mixing necessary

Sika Reemat - Base Resin
Apply Sikalastic®-641 Lo-VOC resin to the primed substrate surface by means of 1/2” (12.7 mm) nap phenolic resin core roller or brush at the specified application rate to achieve a uniform and consistent wet mil thickness (reference separate System Data Sheet). Material can also be squeegee or spray applied, in which case it should also be backrolled. Apply Sika Reemat into the wet embedment resin and roll the scrim to achieve full saturation and embedment. Reemat shall be cut to conform to substrate transitions and flashing conditions, with a typical 2” (50.8 mm) reinforcement overlap. Resin shall saturate the Reemat from below. Apply additional Sikalastic®-641 Lo-VOC resin as required to ensure full scrim embedment. Allow to cure completely before applying subsequent resin layers.

Sika Reemat - Intermediate and Top Resin
Apply Sikalastic®-641 Lo-VOC resin to the cured Sikalastic®/Reemat base layer by means of 1/2” (12.7 mm) nap phenolic resin core roller or brush at the specified application rate to achieve a uniform and consistent wet mil thickness (reference separate System Data Sheet). Material can also be squeegee or spray applied, in which case it should also be backrolled. Allow to cure completely before applying any subsequent resin layer, if specified.

Sika Fleece
Apply Sikalastic®-641 Lo-VOC resin to the primed substrate surface by means of 1/2” (12.7 mm) nap phenolic resin core roller or brush to achieve a uniform and consistent thickness, applying approximately 2/3 of the resin required to achieve the specified application rate (reference separate System Data Sheet). Apply Sika Fleece into the wet embedment resin and roll the fleece to achieve partial saturation and full embedment. Fleece shall be cut to conform to substrate transitions and flashing conditions, with typical 3” (76.2 mm) side and 6” (152.4 mm) end reinforcement overlaps. Resin shall saturate the Fleece from below. Apply remaining 1/3 of the specified resin quantity to to ensure full fleece saturation and an even resin application.

Clean all tools and application equipment with appropriate solvent immediately after use. Hardened and/or cured material can only be removed mechanically.

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