Sikalastic®-621 TC

• Miami Dade
• ASTM E 108
• Florida Building Code
• ASTM D 6083
• UL 790 Class A
• ASTM C 836
• FM Approval Standard 4470 for Class 1 Roof Covers

Single component, moisture-triggered, aliphatic polyurethane

9 months

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

Sikalastic® 621 TC System Guide for Metal Roofs

Metal Roof

* Detailing: Sika® Flexitape Heavy or Sika® Joint Tape SA centered over seams, transitions and properly treated cracks and joints

Sikalastic® 621 TC System Guide with Sika® Reemat Premium

Sikalastic® 621 TC System Guide with Sika® Reemat Premium
 

Sikalastic® 621 TC System Guide with Sika® Fleece

** Substrates: Concrete or cementious, metals, wood, single-ply or bituminous, stone.rimer required (see Substrate Priming Guide).
Detailing: Sika® Flexitape Heavy or Sika® Joint Tape SA centered over seams, transistions and properly treated cracks and joints.
Note: Coverage rates provided are optimal and are not guaranteed - coverage rates will vary depending on temperature, surface roughness and porosity, aggregate selection and embedment, and application technique.

Note: Data for other Sikalastic assemblies available upon request

Note: Data for other Sikalastic assemblies available upon request

Note: Data for other Sikalastic assemblies available upon request

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.

-22 °F (30 °C) min. / 176 °F (80 °C) max.

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®-621 TC is designed for fast curing. High temperatures combined with high air humidity will increase the curing process. Material in opened containers should be applied immediately. In opened containers, the material will form a film after 1 hour approx. (75 °F, 24 °C / 50 % R.H.).

 *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.

Note: Times are approximate and will be affected by changing ambient conditions particularly temperature and relative humidity.

Refer to Priming Guide to select primer for properly evaluated and prepared substrate. Refer to separate primer Product Data Sheet for application methods, coverage rates, cure times and recoat windows. Always allow primer to cure thoroughly before applying detail or base resin layer.
 

Sikalastic® 621 Roofing System Priming Guide
Substrates and Primer Options

Concrete *1
Sikalastic® Concrete Primer Lo-VOC
Sikalastic® DTE Primer
Sikalastic® GDC Primer
Sikalastic® EP Primer/Sealer
Sikalastic® EP Primer Rapid
Lightweight Structural Concrete *1
Sikalastic® Concrete Primer Lo-VOC 
Sikalastic® DTE Primer
Sikalastic® GDC Primer
Sikalastic® EP Primer/Sealer
Sikalastic® EP Primer Rapid
Cement, Gypsum Based Roof Boards
Sikalastic® Concrete Primer Lo-VOC
Sikalastic® EP Primer/Sealer
Sikalastic® EP Primer Rapid
Brick, Stone *3
Sikalastic® Concrete Primer Lo-VOC
Sikalastic® EP Primer/Sealer
Sikalastic® EP Primer Rapid
Bituminous Substrate Asphalt, Bituminous Felts, Bituminous Coatings, Granulated or Smooth SBS & Aged APP Cap Sheets *2,3
Sikalastic® EP Primer/Sealer
Sikalastic® EP Primer Rapid
Single Ply PVC Membranes *3 Sarnafil, Sikaplan *3
Sikalastic® EP Primer/Sealer
Hypalon *3
Sika® Bonding Primer
TPO, EPDM *3
Sikalastic® EPDM / TPO Primer Lo-VOC
Roof tiles (unglazed) *3,4
Sikalastic® EP Primer/Sealer
Sikalastic® EP Primer Rapid
Fiberglass *3
Sikalastic® EP Primer/Sealer
Sikalastic® EP Primer Rapid
Polyurethane Foam - Sprayed or Slab Stock
Sikalastic® EP Primer/Sealer
Sikalastic® EP Primer Rapid
Metal *3 Aluminium, Galvanized, Cast Iron, Copper, Lead, Brass, Stainless Steel, Steel, Zinc
Sikalastic® EP Primer/Sealer
Sikalastic® EP Primer Rapid
Pre-Coated Metal *3 Paints & Coatings *3 Aluminized Solar Reflective Coatings *3
Sikalastic® EP Primer/Sealer
Sikalastic® EP Primer Rapid
Wood - Timber & Plywood *5
Sikalastic® Concrete Primer Lo-VOC
Sikalastic® EP Primer/Sealer
Sikalastic® EP Primer Rapid
* Consult Sika
1 New cementitious substrates must be Portland base and be cured min. 28 days
2 The presence of volatile bitumen may cause discoloration of Sikalastic® if not properly primed
3 Surface evaluation and field adhesion testing
4 Glazed tile consult Sika
5 Pressure treated lumber consult Sika

No mixing necessary for resins

PRIMER MIXING
Refer to the individual primer Product Data Sheets for proper mixing instruction.

Detailing

Non-structural Cracks Up To 1/16''
Detail application not necessary. Apply embedment/base resin layer per instruction. Non?structural cracks between 1/16'' and 1/4'' Rout and seal with Sikaflex® sealant. Apply 40–45 mil resin layer embedded with 3'' Sika Flexitape Heavy or use Sika® Joint Tape SA centered over the crack. Apply embedment/base resin layer per instruction.

Cracks and Joints Between 1/4" and 1''
Rout and sealwith Sikaflex® sealant. Apply bond breaker tape sufficient to span width of crack or joint followed by 40-45 mil resin layer embedded with 6'' Sika® Flexitape Heavy or use Sika® Joint Tape SA centered over crack or joint. Apply embedment/base resin layer by terminating Sika® Reemat or Sika® Fleece at edges of crack or joint overlapping Sika® Flexitape Heavy or Sika® Joint Tape SA, a minimum of 2 inches on both sides of the crack or joint.

Joints Greater Than 1''
Treat as expansion joint. Consult Sika for recommendations.

Metal Seams and Plywood/Cover Board Joints
Apply 40–45 mil resin layer embedded with 3 or 6'' Sika® Flexitape Heavy centered over seam. Alternativly Sika® Joint Tape SA can be applied centered over seam. Apply embedment resin layer per below.

Transitions Between Dissimilar Materials
Apply 40-45 mil resin layer embedded with Sika® Flexitape Heavy or use Sika® Joint Tape SA centered over edge. Apply embedment/base resin layer per instruction.

Embedment/Base Resin Layer with Sika® Reemat Premium Reinforcement
Mixing not required. Apply Sikalastic®-621 TC with a 1/2'' nap phenolic resin core roller. Material can also be squeegee or spray applied, in which case it should be backrolled prior to embedding Sika® Reemat Premium. Place Sika® Reemat Premium in wet base resin layer overlapping seams a minimum of 2'' (place frayed edge over cut edge of roll) and apply wet roller to topside to saturate completely. After approximately 5 minutes the binder will begin to dissolve allowing the fiber strands to conform to irregular surfaces. Do not over work once the fibers have conformed to the substrate. Allow to cure 12 hours at 70 °F and 50 % R.H. or until tack free before top resin layer. Keep clean and dry and apply top resin layer within 7 days. If window is exceeded clean with non-sudsing detergent and clean water rinse, and allow to dry prior to application of Sika® Concrete Primer Lo-VOC or Sika® Reactivation Primer.

Top Resin Layer with Sika® Reemat Premium Reinforcement
Mixing not required. Apply Sikalastic®-644 Lo-VOC with a 1/2'' nap phenolic resin core roller. Material can also be squeegee or spray applied, in which case it should also be backrolled. In the case of Sikalastic 25-year system allow the first top resin layer to cure 12 hours at 70 degrees F and 50 % R.H. or until tack free before applying second top resin layer. On top of the complete Sikalastic system additional resin layers may be applied with aggregate for slip resistance. Keep clean and dry and apply additional resin layers within 7 days. If window is exceeded clean with non-sudsing detergent and clean water rinse, and allow to dry prior to application of Sika® Concrete Primer Lo-VOC or Sika® Reactivation Primer.

Wet on Wet Application with Sika® Fleece Reinforcement
Mixing not required. To primed substrate apply two?thirds of the Sikalastic®-621 TC with a 1/2'' nap phenolic resin core roller. Immediately place specified Sika Fleece into wet resin overlapping seams a minimum of 3” along the edge and 6” end-to-end. Apply wet roller to topside with light pressure to saturate fleece from bottom and ensure air pockets are completely removed. Immediately apply all of remaining one-third of Sikalastic®-644 Lo-VOC resin. Ensure even and complete fleece saturation from topside.

Aggregated Surfacing
Supplemental aggregate surfacing is required for all applications that will experience direct foot traffic such as balconies, terraces, walkways, and plazas. It is also recommended for areas that experience maintenance foot traffic. The aggregate surfacing is applied in a supplemental resin layer after the Sikalastic membrane has been installed. Aggregate is not applied into the top layer of the roofing/waterproofing membrane resin.

Seed and Back Roll Option
This option is primarily intended for use for maintenance traffic-type applications where enhanced slip resistance is required. Apply Sikalastic®- 621 TC resin at 15 mils wet film thickness to the installed, cured membrane system. While the supplemental resin application is still wet seed with kiln dried, iron free aggregate. Back roll the surface to encapsulate the aggregate in the Sikalastic resin.

Full Broadcast and Seal Option
This option is intended for use for applications where both enhanced slip resistance and physical protection of the roofing membrane is required. Apply Sikalastic®-621 TC resin at 15 mils wet film thickness to the installed, cured membrane system. While the supplemental resin application is still wet broadcast to rejection (full broadcast/beach) with kiln dried, iron free aggregate. Remove excess aggregate after cure. Seal with an additional coat of Sikalastic resin.

Aggregate Selection
Use clean, rounded or semiangular, oven dried quartz sand with a minimum hardness of 6.5 per the Moh’s scale. It should be supplied in prepackaged bags and free of metallic or other impurities. The following size gradations are recommended: ▪ 16–30 or 20–40 mesh for pedestrian traffic systems.

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