Sikalastic®-641
Sikalastic®-641 is a 1-part polyurethane, reinforced, low odour, cold-applied liquid membrane. It provides a UV-stable, seamless, elastic, low maintenance, durable, smooth waterproof finish using Sika's unique i-Cure technology. The product is suitable for hot and cold climates.
- 1-part, no mixing, easy and ready to use
- Thickness: ~1.50–2.2 mm
- Resistant to UV exposure
- Highly reflective (~RAL 9016, available on indent)
- Resistant to yellowing
- Cold applied – requires no heat or flame
- Low odour - suitable for odour sensitive projects
- High solids content
- Seamless
- Easy to detail with Sika® Reemat Premium
- Easily recoated - no removal required
- Vapour permeable
- Applied by brush / roller
- Elastic and crack bridging
- Retains flexibility at low temperatures
- Good adhesion to most construction substrates
- Fast curing
- Resistant to common atmospheric conditions
Usage
- Top coat for SikaRoof® i-Cure-15/18/22 systems in both new construction and refurbishment projects
- Top coat for the ETA approved, low odour SikaRoof iCure-15/18/22 systems.
- Waterproofing structures with numerous details such as penetrations, drains, roof lights and complex geometry
- Cost efficient service life extension of failing roofs
- As a reflective top coat (traffic white ~RAL 9016, available on indent) providing cool roof characteristics and solar efficient roofs
- For odour sensitive areas
- Only for exterior use
Advantages
- 1-part, no mixing, easy and ready to use
- Thickness: ~1.50–2.2 mm
- Resistant to UV exposure
- Highly reflective (~RAL 9016, available on indent)
- Resistant to yellowing
- Cold applied – requires no heat or flame
- Low odour - suitable for odour sensitive projects
- High solids content
- Seamless
- Easy to detail with Sika® Reemat Premium
- Easily recoated - no removal required
- Vapour permeable
- Applied by brush / roller
- Elastic and crack bridging
- Retains flexibility at low temperatures
- Good adhesion to most construction substrates
- Fast curing
- Resistant to common atmospheric conditions
Packaging
15 litre containers.
Colour
Slate grey (~RAL 7015)
Product Details
ENVIRONMENTAL INFORMATION
- Conformity with LEED v4 MRc 4 (Option 2): Building Product Disclosure and Optimization - Material Ingredients
- BRE Environmental Product Declaration (EPD)
APPROVALS / STANDARDS
- CE Marking and Declaration of Performance to ETA 14/0177
- European Technical Assessment ETA 14/0177 based on ETAG 005 Part 1 and 6 - Liquid-applied roof waterproofing using kits based on polyurethane
- External Fire Exposure to Roofs - 10 Year System BS 476 Part 3: 2004, Sikalastic®-641, Exova, Test report No. 336139
- External Fire Exposure to Roofs - 10 Year System DD CEN/TS 1187:2012 Test 1, Sikalastic®-641, Exova, Test report No. 336143
- External Fire Exposure to Roofs - 25 Year System BS 476 Part 3, Sikalastic®-641, Exova, Test report No. 336140
- External Fire Exposure to Roofs - 25 Year System DD CEN/TS 1187:2012 Test 1, Sikalastic®-641, Exova, Test report No. 336141
- Fire Testing with Burning Brands, Wind and Radiant Heat- 10 Year System DD CEN/TS 1187:2012 Test 4, Sikalastic®-641, Exova, Test report No. 336142
- Fire Testing with Burning Brands, Wind and Radiant Heat- 25 Year System DD CEN/TS 1187:2012 Test 4, Sikalastic®-641, Exova, Test report No. 336141
- Odour comparison Sikalastic®-641, Odournet, Report No. 456-2014-17
- Odour comparison Sikalastic®-641, Odournet, Report No. 456-2014-19
- Reaction to Fire - 25 Year System EN 13501-5: 2007 + A1: 2009, Sikalastic®-641, Exova, Classification report No. WF 336207
- Roof Coverings Exposed to External Fire - 10 Year System EN 13501-1: 2005 + A1: 2009 Test 4, Sikalastic®-641, Exova, Classification report No. WF 336203
- Roof Coverings Exposed to External Fire - 10 Year System EN 13501-1: 2005 + A1: 2009, Sikalastic®-641, Exova, Classification report No. WF 336206
- Roof Coverings Exposed to External Fire - 10 Year System EN 13501-5: 2005 + A1: 2009, Sikalastic®-641, Exova, Classification report No. WF 336204
- Roof Coverings Exposed to External Fire - 25 Year System EN 13501-1: 2005 + A1: 2009 Test 4, Sikalastic®-641, Exova, Classification report No. WF 336202
- Roof Coverings Exposed to External Fire - 25 Year System EN 13501-5: 2005 + A1: 2009, Sikalastic®-641, Exova, Classification report No. WF 336205
Chemical Base
Aliphatic polyurethane
Shelf Life
9 months from date of production
Storage Conditions
The product must be stored in original, unopened and undamaged sealed packaging in dry conditions at temperatures between +0 °C and +25 °C. Always refer to packaging.
Density
| ~1.42 kg/l | (EN ISO 2811-1) |
Value +23°C
Solid content by weight
~88.0 % (+23 °C / 50 % r.h.)
Solid content by volume
~84.0 % (+23 °C / 50 % r.h.)
System Structure
Refer to System Data Sheet:
- SikaRoof® i-Cure-15
- SikaRoof® i-Cure-18
- SikaRoof® i-Cure-22
Tensile Strength
| Unreinforced | 6.0 N/mm2 |
External Fire Performance
| BRoof (t1) + (t4) over Build up roofing system | (ENV 1187) |
Reaction to Fire
| Euroclass E |
Solar Reflectance Index
| ≥ 108* | (ASTM 1980) |
* All values refer to the initial (properly cured, non-weathered) status of Sikalastic®-641 white (RAL 9016, available on indent).
Service Temperature
-30 °C to +90 °C
Dry film thickness
| Roofing system | Thickness |
| SikaRoof® i-Cure-15 | 1.5 mm |
| SikaRoof® i-Cure-18 | 1.8 mm |
| SikaRoof® i-Cure-22 | 2.2 mm |
Application
Product Temperature
It is recommended the product is stored under warm conditions (+20 °C) prior to application at temperatures below +10 °C.
Ambient Air Temperature
+5 °C min / +40 °C max
Relative Air Humidity
20 % r.h. min / 85 % r.h. max
Substrate Temperature
+5 °C min. / +60 °C max.
Dew Point
Beware of condensation.
The substrate and uncured applied product must be at least +3 °C above dew point to reduce the risk of condensation or blooming on the surface of the applied product.
Substrate Moisture Content
≤4 % parts by weight.
Test method: Sika®-Tramex meter
No rising moisture according to ASTM (Polyethylene-sheet).
Substrate Pre-Treatment
Refer to System Data Sheets: SikaRoof® systems.
Pot Life
~1 hour (+20 °C / 50 % r.h.)
Times are approximate and will be affected by changing ambient conditions particularly temperature and relative humidity.
Material in opened containers must be applied immediately. In opened containers, the material will form a film after ~1 hour.
Waiting Time / Overcoating
| Ambient conditions | Minimum waiting time1 |
| +5 °C / 50 % r.h. | ~18 hours |
| +10 °C / 50 % r.h. | ~8–10 hours |
| +20 °C / 50 % r.h. | ~4–6 hours |
| +30 °C / 50 % r.h. | ~4 hours |
1 After four days, the surface must be cleaned and primed with Sika® Reactivation Primer before continuing.
Times are approximate and will be affected by changing ambient conditions particularly temperature and relative humidity.
Applied Product Ready for Use
| Ambient conditions | Rain resistant1 | Touch dry | Full cure2 |
| +5 °C / 50 % r.h. | 1 hour | 10–12 hours | 24 hours |
| +10 °C / 50 % r.h. | 1 hour | 6–8 hours | 18–24 hours |
| +20 °C / 50 % r.h. | 1 hour | 4–6 hours | 12–18 hours |
| +30 °C / 50 % r.h | 1 hour | 3–5 hours | 8–12 hours |
1 Be aware that the impact of heavy rain or rain showers can physically mark or damage the still liquid membrane.
2 Application at higher than recommended film thicknesses may result in a prolonged “soft” feel to the coating. This will eventually cure.
Note: Times are approximate and will be affected by changing ambient conditions, particularly temperature and relative humidity.
SUBSTRATE PREPARATION
General
Refer to System Data Sheet or System Method Statement for information on preparing substrates to receive the base coat application of Sikalastic-631.
Apply Sikalastic®-641 to the fully cured Sikalastic-631 within four days after the base coat application. If more than four days has passed, the base coat surface must be prepared with Sika Reactivation Primer prior to top coat application. Refer to the PDS for Sika Reactivation Primer for further information.
Existing Sikalastic®-641 system
Clean the membrane surface using a power wash at ~14 N/mm2 (2000 psi) including detergent then rinse thoroughly and allow to dry. Existing Sikalastic®-641 systems older than four days must be prepared with Sika Reactivation Primer as outlined above.
MIXING
Sikalastic®-641 is supplied ready for use. Before application, stir for a minimum of 1 minute using mixing paddle and drill or other suitable equipment to mix the liquid and all the coloured pigment until a uniform colour has been achieved. Over-stirring must be avoided to minimise air entrainment.
APPLICATION
Reference must be made to further documentation where applicable, such as relevant method statement, application manual and installation or working instructions.
General
Always begin application with detailing before installation of the main horizontal surfaces.
Primer
Pour the appropriate mixed primer onto the prepared substrate and apply by brush or appropriate roller. Ensure a continuous, pore free coat covers the substrate. Confirm primer waiting / overcoating time has been achieved before applying successive products. Refer to individual primer Product Data Sheet.
Base coat
Refer to the System Data Sheet or the System Method Statement.
Reinforcement
Refer to the System Data Sheet or the System Method Statement.
Top coat
Pour stirred Sikalastic®-641 onto the fully cured, reinforced base coat layer, and apply evenly by brush or short piled roller at the required consumption rate in 2 directions at right angles to each other. Confirm overcoating times before application. Refer to the System Data Sheet or the System Method Statement.
Ensure each application / coat is clean and dry before applying next coat.
Note: Material will dry on the surface in around 30 minutes depending on temperature and humidity conditions. Always maintain a wet edge and finish surface as work proceeds. Returning to re-work areas that are partially dried may damage the surface.
CLEANING OF TOOLS
Clean all tools and application equipment with Thinner C immediately after use. Hardened material can only be removed mechanically.