Sikalastic®-621 TC
Sikalastic®-621 TC is a cold applied, highly elastic, aliphatic, single component, moisturetriggered polyurethane resin designed for easy application as part of Sikalastic®-601/621 RoofPro roofing systems.
- Proven technology - over 30 year track record
- One component – no mixing, easy and ready to use
- UV resistant - Highly reflective (RAL9016) and resistant to yellowing
- Cold applied - requires no heat or flame
- Seamless roof waterproofing membrane
- Compatible with Sika® Reemat Premium - easy to detail
- Fast curing - free from resin damage almost immediately on application
- High elastic and crack-bridging - retains flexibility even at low temperatures
- High root resistance
- Easily re-coated when needed - no stripping required
- Good adhesion to most substrates- see primer chart
- Vapour permeable - allows substrate to breathe
- Strong resistance to common atmospheric chemicals
Usage
- Top coat resin for Sikalastic® RoofPro 10, 15 & 20 year systems reinforced with Sika Reemat.
- Embedment resin for Sikalastic® RoofPro 25 year systems reinforced with Sika Reemat.
- Saturating resin for Sikalastic® RoofPro 15, 20 and 25 year systems reinforced with Sika Fleece.
- Typically applied in Sikalastic® RoofPro Direct, Recover, Built-Up, Inverted, and Vegetate systems for both new construction and refurbishment
Advantages
- Proven technology - over 30 year track record
- One component – no mixing, easy and ready to use
- UV resistant - Highly reflective (RAL9016) and resistant to yellowing
- Cold applied - requires no heat or flame
- Seamless roof waterproofing membrane
- Compatible with Sika® Reemat Premium - easy to detail
- Fast curing - free from resin damage almost immediately on application
- High elastic and crack-bridging - retains flexibility even at low temperatures
- High root resistance
- Easily re-coated when needed - no stripping required
- Good adhesion to most substrates- see primer chart
- Vapour permeable - allows substrate to breathe
- Strong resistance to common atmospheric chemicals
Packaging
5 gal. (19 L) metal pail
Color
White (RAL 9016), Pearl Gray, Steel Gray, Mushroom, Copper Green; custom colors available with minimum order.
Product Details
APPROVALS / STANDARDS
As part of Sikalastic®-601/621 RoofPRO Roofing System:
- FM Approval Standard 4470 for Class 1 Roof Covers
- ASTM E-108-00 Spread of Flame meets Class A at a slope of 1 in 12
- Simulated wind uplift pull testing meets up to Class 1-990
- Simulated hail damage testing meets rating of SH - Severe Hail
- Miami-Dade County NOA for Roof Systems over Concrete and Steel Decks
- USGBC LEED rating: Conforms to LEED SS Credit 7.2 for Heat Island Effect - Roof with SRI >/=78
- Meets ASTM D7311-07: Standard Specification for Liquid-Applied, Single-Pack, Moisture-Triggered, Aliphatic Polyurethane Roofing Membrane.
Chemical Base
One-component, moisture-triggered aliphatic polyurethane
Shelf Life
9 months from date of production
Storage Conditions
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
Density
| ~12 lb./gal. (~1.44 kg/l) (73 °F, 23 °C) |
Solid content by volume
| 81 % | (ASTM D-2697) |
Volatile organic compound (VOC) content
| 183 g/l | (ASTM D-2369-81) |
System Structure
Please refer to Sikalastic®-601/621 System Data Sheet
Tensile Strength
| Please refer to Sikalastic®-601/621 System Data Sheet | (ASTM D-751) |
Tear Strength
| Please refer to Sikalastic®-601/621 System Data Sheet | (ASTM D-751) |
Resistance to Static Puncture
| Please refer to Sikalastic®-601/621 System Data Sheet | (ASTM D-5602) |
External Fire Performance
| Class A | (ASTM E 108) |
Chemical Resistance
Strong resistance to a wide range of reagents including paraffin, petrol, fuel oil, white spirit, acid rain, detergents and moderate solutions of acids and alkalis. Some low molecular weight alcohols can soften the material. Contact Sika technical service for specific information.
Solar Reflectance
| 0.87* | (ASTM C-1549) |
*All values refer to the initial (properly cured, non-weathered) status of Sikalastic®-621 TC white (RAL 9016).
Solar Reflectance Index
| ≥ 108* | (ASTM 1980) |
*All values refer to the initial (properly cured, non-weathered) status of Sikalastic®-621 TC white (RAL 9016).
Service Temperature
-22 °F (30 °C) min. / 176 °F (80 °C) max.
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.
Substrate Moisture Content
≤4 % pbw moisture content.
Test method: Sika®-Tramex meter
No rising moisture according to ASTM (Polyethylene-sheet).
Pot Life
Sikalastic®-621 TC is designed for fast curing. High temperatures combined with high air humidity will increase the curing process. Thus, material in opened containers should be applied immediately. In opened containers, the material will form a film after 1 hour approx. (68 °F, 20 °C / 50 % R.H.).
Waiting / Recoat Times
| Ambient conditions | Minimum waiting time overcoating |
| +40 °F / 50 % r.h. | 14 hours |
| +50 °F / 50 % r.h. | 6 hours |
| +70 °F / 50 % r.h. | 5 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. | 10 min. | 12 hours | 24 hours |
| +50 °F / 50 % r.h. | 10 min. | 6 hours | 18–24 hours |
| +70 °F / 50 % r.h. | 10 min. | 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 |
| 80 sf/gal.–20 mils wet film thickness | 25 sf/gal.–65 mils wet film thickness |
| 53 sf/gal.–30 mils wet film thickness | 20 sf/gal.–80 mils wet film thickness |
| 45 sf/gal.–35 mils wet film thickness | 16 sf/gal.–100 mils wet film thickness |
| 35 sf/gal.–45 mils wet film thickness |
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®-621 TC resin. Reference separate System Data Sheet for specific primer recommendations.
MIXING
No mixing necessary
APPLICATION
Sika Reemat - Base Resin
Apply Sikalastic®-621 TC 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®-621 TC 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®-621 TC 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®-621 TC 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