Sikalastic®-644 Lo-VOC
Sikalastic®-644 Lo-VOC is a cold applied , highly elastic, aliphatic, single component, alkali resistant, moisture-triggered polyurethane resin designed for easy application as part of Sikalastic®-644 Lo-VOC RoofPro waterproofing systems.
- Proven technology with over 30 year track record
- Single component - no mixing and ready to use
- Alkaline resistant - suitable for under tile applications
- 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®-644 Lo-VOC RoofPro Waterproofing systems reinforced with Sika® Reemat.
- Saturating resin for Sikalastic®-644 Lo-VOC RoofPro systems reinforced with Sika® Fleece.
- Typically applied in Sikalastic® RoofPro Direct, Plaza, Foundation wall, and Vegetated systems for both new construction and refurbishment.
- Ideal for applications involving cementitious overlays and tile mortar.
Advantages
- Proven technology with over 30 year track record
- Single component - no mixing and ready to use
- Alkaline resistant - suitable for under tile applications
- 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) pails
Color
White, Pearl Gray; custom colors available with minimum order quantitiy
Product Details
Chemical Base
Single component, moisture-triggered, aliphatic polyurethane
Shelf Life
15 months in original, unopened and undamaged sealed containers
Storage Conditions
Store dry between 35 and 77 °F (2–25 °C). Sondition material to 50 - 77 °F (10 - 25°C) before using for ease of application.
Density
11.76 lb./gal. (1409.1 kg/m3)
Solid content by volume
| 80.25 % | (ASTM D-2697) |
Volatile organic compound (VOC) content
| 14.74 g/l | (ASTM D-2369-81) |
Tensile Strength
| Please refer to Sikalastic®-644 Lo-VOC System Data Sheet | (ASTM D-751) |
Tear Strength
| Please refer to Sikalastic®-644 Lo-VOC System Data Sheet | (ASTM D-751) |
Resistance to Static Puncture
| Please refer to Sikalastic®-644 Lo-VOC System Data Sheet | (ASTM D-5602) |
Chemical Resistance
Most common roofing contaminants, oils, grease, dilute acids and base
Service Temperature
-22–176 °F (-30–80 °C) intermittent
Application
Ambient Air Temperature
41 °F (5 °C) min. / 95 °F (35 °C) max.
Relative Air Humidity
80 % R.H. max.
Substrate Temperature
41 °F (5 °C) min. / 140°F (60°C) max.
Dew Point
Beware of condensation.
The substrate and uncured coating must be ≥ 5 °F (3 °C) above dew point.
Pot Life
Sikalastic®-644 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.)
Waiting / Recoat Times
| Ambient conditions | Minimum waiting time overcoating |
| +40 °F / 50 % r.h. | 18 hours |
| +50 °F / 50 % r.h. | 8 hours |
| +70 °F / 50 % r.h. | 6 hours |
*After 7 days the surface must be cleaned and primed with Sika® Reactivation Primer before continuing.
Note: Times are approximate and will be affected by changing ambient conditions particularly temperature and relative humidity.
Applied Product Ready for Use
| Ambient conditions | Rain resistant | Touch dry | Full cure |
| +40 °F / 50 % r.h. | 1 hour | 12 hours | 24 hours |
| +50 °F / 50 % r.h. | 1 hour | 6 hours | 18–24 hours |
| +70 °F / 50 % r.h. | 1 hour | 4 hours | 12–18 hours |
Note: Times are approximate and will be affected by changing ambient conditions particularly temperature and relative humidity.
Coverage
| Sika Reemat | Sika Fleece |
| 53 sf/gal - 30 mils wet film thickness | 23 sf/gal - 70 mils wet film thickness |
| 44 sf/gal - 40 mils wet film thickness | 21 sf/gal - 75 mils wet film thickness |
| 35 sf/gal - 45 mils wet film thickness | 17 sf/gal - 95 mils wet film thickness |
NOTE: Coverage rates are optimal - coverage rates will vary depending on temperature, surface roughness and porosity, and application technique.
SUBSTRATE PREPARATION
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®-644 Lo-VOC resin. Reference separate System Data Sheet for specific primer recommendations.
MIXING
No mixing necessary
APPLICATION
Sika® Reemat - Base Resin - Apply Sikalastic®-644 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®-644 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®-644 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 subsequent resin layer, if specified.
Sika® Fleece - Apply Sikalastic®-644 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.
CLEANING OF TOOLS
Clean all tools and application equipment with appropriate solvent immediately after use. Hardened and/or cured material can only be removed mechanically