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Sikalastic®-621 TC

High performance, one-component, liquid applied polyurethane top coat for SikaRoof® MTC roof waterproofing systems

Sikalastic®-621 TC is a cold-applied, one-component, seamless, highly elastic and UV-stable moisture-triggered polyurethane Top Coat (TC) designed to provide easy application and a durable solution as part of the SikaRoof® MTC systems, as well as for detailing on single ply membranes. Suitable for use in hot and tropical climatic conditions.

  • Proven technology - over 25 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
Sikalastic®-621 TC
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Usage

  • Top Coat for SikaRoof® MTC 12, 15, 18, 22 in both new construction and refurbishment projects
  • For roofs displaying complex detail areas and geometry, even when accessibility is limited
  • For cost efficient life cycle extension of failing roofs
  • Highly reflective top coat Sikalastic®-621 TC - SR (traffic white RAL 9016) as part of the Sika SolaRoof™ MTC systems for excellent cool roof characteristics and bi-facial photovoltaic panels.
  • For detailing solutions on singly ply membranes
 

Advantages

  • Proven technology - over 25 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 L (~7.2 kg) metal pail

15 L (~21.6 kg) metal pail

Colour

Slate grey (RAL 7015), shale grey (RAL 8500), traffic white (RAL 9016), other colours available upon request

Product Details

Sustainability / Certifications / Approvals

APPROVALS / CERTIFICATES

As part of SikaRoof® MTC Systems

  • Liquid applied roof waterproofing kit according to ETAG 005, ETA - 09 / 0139 issued by technical assessment body British Board of Agrément (BBA) provided with the CE marking, Declaration of Performance
    SikaRoof® MTC 12: 44125185
    SikaRoof® MTC 15: 27265077
    SikaRoof® MTC 18: 15813688
    SikaRoof® MTC 22: 75346978
  • Root resistance approval according FLL (Institute of Horticulture)
  • Reaction to fire according to EN 13501-1: Euroclass E
  • External fire performance according to EN 13501-5:
  • BRoof (t1) - BRoof (t4) (SikaRoof® MTC 15, non-combustible substrates)
  • BRoof (t1) - BRoof (t4) (SikaRoof® MTC 18, build up roofs)
  • BRoof (t1) (SikaRoof® MTC 22, Build up roofs)
Product Information

Composition

One-component, moisture-triggered aliphatic polyurethane

Shelf life

9 months from date of production

Storage conditions

The product must be stored properly in original, unopened and undamaged sealed packaging in dry conditions at temperatures between 0 °C and +25 °C.
Higher storage temperatures may reduce shelf life of product.
Reference shall also be made to the storage recommendations within the safety data sheet.

Density

~1.44 kg/l (23 °C)

(EN ISO 2811-1)

Solid content

~81.3 % by weight

~87.4 % by volume
System information

System Structure

Please refer to System Data Sheets of SikaRoof® MTC Systems
Technical Information

Chemical Resistance

Salt spray

1000 h
continuous exposure

Prohesion testing1000 h
cyclic exposure

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 Technical Department for specific information.

Solar Reflectance Index

≥ 109*

(ASTM 1980)

*All values refer to the initial (properly cured, non-weathered) status of Sikalastic®-621 TC white (RAL 9016).

Service Temperature

-30 °C min. / +80 °C max.

Application

Application Information

Ambient Air Temperature

+5 °C min. / +35 °C max.

Relative Air Humidity

5 % r.h. min. / 85 % r.h. max.

Substrate Temperature

+5 °C min. / +60 °C max.
≥ 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).

Substrate Pre-Treatment

Please refer to System Data Sheets of SikaRoof® MTC Systems

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 – 2 hours approximately (+20 °C / 50 % r.h.).

Waiting Time / Overcoating

Ambient conditions

Minimum waiting time

+5 °C / 50 % r.h.

18 h

+10 °C / 50 % r.h.8 h
+20 °C / 50 % r.h.6 h

*After four 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 resistance

Touch dry

Full cure

+5 °C / 50 % r.h.

10 min

8 – 12 h

16 – 24 h

+10 °C / 50 % r.h.

10 min

4 h

8 – 12 h

+20 °C / 50 % r.h.

10 min

3 h

6 – 8 h

*Be aware that impact of heavy rain or rain showers can physically damage the still liquid membrane.
Note: Times are approximate and will be affected by changing ambient conditions particularly temperature and relative humidity.
Application steps

SUBSTRATE PREPARATION

The surface must be sound, of sufficient strength, clean, dry and free of dirt, oil, grease and other contamination. Depending on the material the substrate must be primed or mechanically cleaned. Grinding may be necessary to level the surface. Suitable substrates are such as: concrete, bituminous felts and coatings, metal, brickwork, asbestos cement, ceramic tiles, wooden substrates.

For detailed information regarding substrate preparation and primer chart please refer to Method Statement.

MIXING

Mixing is not required, however if the product is settled or separated on opening, stir Sikalastic®-621 TC gently but thoroughly in order to achieve a uniform colour. Stirring gently will minimise air entrainment.

APPLICATION

Prior the application of Sikalastic®-621 TC the priming coat if used must have cured tack-free. For the Waiting Time / Overcoating please refer to the Product Data Sheet of the appropriate primer. Damageable areas (handrails etc) have to be protected with tape or plastic wrapping.

Please note, always begin with details prior to the installation of the horizontal surface.

  1. Apply first coat of Sikalastic®-601 BC. Work only so far in advance that the material stays liquid.
  2. Roll in the Sikalastic® Reemat. Overlap the Reemat a minimum 5 cm and ensure overlaps are sufficiently wet to bond both layers.
  3. The roller may require only a little extra material to keep wetted but no further significant material needs to be added at this stage.
  4. After the coat is dry enough to walk on, seal the roof area with second coat of Sikalastic®-621 TC.
  5. For SikaRoof MTC 22 apply a third coat of Sikalastic®-621 TC.

CLEANING OF EQUIPMENT

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

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