Sikalastic®-641 Lo-VOC

Environmental Product Declaration (EPD) - Cradle-to-Grave

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

Single component, moisture triggered aliphatic Polyurethane

15 months - 5 gal pail
  6 months - 50 gal drum

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

11.9 lb./gal. (1.4 kg/cm³)

Sikalastic® -641 Lo-VOC System Guide for Metal Roof
 

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

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Sikalastic® -641 Lo-VOC System Guide with Sika® Reemat Premium
 

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Sikalastic® -641 Lo-VOC System Guide with Sika® Fleece
 

* Substrates: Concrete or cementious, metals, woods, single-ply or bituminous, stone. Primer required (see Substrate Priming Guide). Detailing: Sika® Flexitape Heavy or Sika® Joint Tape SA centered over seams, transistions and properly treated cracks and joints
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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. For example, using Sikalastic®-641 Lo-VOC Roofing System with Sika® Fleece 140 in a Sikalastic 20 build up, a potential full system coverage rate for a mod-bit surface could be 14 - 16 sf/gal.. Sikalastic®-641 Lo-VOC Roofing System with Sika Reemat Premium in a Sikalastic 15, 20 & 25 build up, a potential base coat coverage rate could be 25 - 28 sf/gal.

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, gasoline, 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 Service for specific recommendations.

-22–176 °F (-30–80 °C) intermittent

Sikalastic® -641 Lo-VOC System Guide for Metal Roof

Sikalastic® -641 Lo-VOC System Guide with Sika® Reemat

Sikalastic® -641 Lo-VOC System Guide with Sika® Fleece

41 °F (5 °C) min. / 95 °F (35 °C) max.

85 % 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®-641 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.)

 *After 7 days the surface must be cleaned and primed with Sika® Concrete Primer Lo-VOC or 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.

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. (Refer to Sikalastic® 641 Lo-VOC System Data Sheet)

NOTE: Please refer to Sikalastic Applicator Manual for detailed instructions on all Sikalastic systems. For professional use only; trained applicators.

All substrate surfaces
Substrates 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®-641 Lo-VOC resin. Reference separate System Data Sheet for specific primer recommendations.

Concrete and Cementitious Substrates
New concrete shall be allowed to cure a minimum of 28 days. Concrete shall have a minimum compressive strength of 20.7 MPa (3000 psi) and exhibit a minimum tensile bond strength of 1.4 MPa (200 psi). Moist or sheet curing methods should be used, as opposed to the use of curing compounds, which may interfere with the bond of the membrane. Inspect the concrete, including upstands. All areas should be hammer or chain drag tested. Concrete must be suitably finished, preferably by wood float or steel pan. A power float finish is acceptable where the surface is prepared to avoid laitance (a tamped finish is not acceptable). The surface finish must be uniform and free from defects such as laitance, voids or honeycombing. Cementitious or mineral based substrates must be prepared mechanically using abrasive blast cleaning or scarifying equipment to remove cement laitance and to achieve an open textured surface (CSP 2-4 per ICRI guidelines). Loose friable material and weak concrete must be completely removed and surface defects such as blowholes and voids must be fully exposed. The amount of embedment coat required may increase over rough or highly porous surfaces. Repairs to the substrate, filling of joints, blowholes/voids and surface levelling must be carried out. Consult Sika for product recommendations based on project requirements. High spots must be removed by grinding or similar method. Outgassing is a naturally occurring phenomenon of concrete that can produce pinholes in liquid applied materials. The concrete must be carefully assessed for moisture content, air entrapment, and surface finish prior to any roofing/waterproofing work. Particular requirements for priming must also be considered. Installing the primer and membrane either when the concrete temperature is falling or stable can reduce outgassing. It is generally beneficial to apply the primer and embedment coat in the late afternoon or evening.
Gypsum and Cement Based Sheathing
Sheathing boards shall be clean, dry,dust free, and shall be properly secured to the structure. Secure loose boards if in sound condition. Damaged or contaminated boards shall be removed and replaced.
Brick and Stone
Mortar joints must be sound and preferably flush pointed. Power wash and use biodegradeable non?sudsing detergent with clean water rinse as required.
Asphalt
Asphalt contains volatiles which can cause bleeding and slight non-detrimental staining. The asphalt must be carefully assessed for moisture and/or air entrapment, grade and surface finish. Power wash and use biodegradeable non-sudsing detergent with clean water rinse as required. All major cracks should be sealed to allow continuity of the Sikalastic® system.
Bituminous Felt
Ensure that bituminous felt is firmly adhered or mechanically fixed to the substrate. Bituminous felt shall not contain badly degraded areas. Power wash and use biodegradeable non-sudsing detergent with clean water rinse as required. Treat blisters by star cutting and removing any underlying water. Allow to dry and re?adhere using suitable adhesive.
Bituminous Coatings
Bituminous coatings should not be sticky or mobile. Volatile mastic coatings, or old coal tar coatings are not acceptible. Remove any loose or degraded coatings.
Metals
Metals must be in sound condition. Ferrous metals should be thoroughly cleaned by grinding or blast cleaning prior to priming (SSPC-SP3 to SP11 near-white metal). Non-ferrous metals are prepared by removing any deposits of dust and oxidation and abrading to bright metal. Wire brushing can be used for soft metal such as lead. The surface must be clean and free from grease which, if present, must be removed with a solvent wipe or wash with detergent, rinse and dry. Stainless Steel must be mechanically abraded or ground to create an appropriate anchor profile.
Wooden Substrates
Plywood and timber based roof decks must be in good condition, firmly adhered or mechanically fixed. All plywood should be identified as conforming to PS 1 for construction and industrial plywood by grade, APA (American Plywood Association) trademark, or equivalent. For maximum smoothness, EXT Type APA, Grade A-C should be used, and the “A” side should be positioned to receive the Sikalastic® resin. Plywood decks to receive resin directly shall be at least 1/2'' thick and attached and supported according to APA guidelines, using only non-rusting screw, spiral or coated nail type fasteners. A good practice would be to recess or counter sink fasteners 1/8 to 1/4'' and fill with Sikaflex® sealant. Suitable edge support to prevent differential deflection between panels shall be provided. Panel edges shall be tongue and groove or supported on solid blocking. Space panels 1/8 to 3/16'' at panel ends. Timber and timber based roof decks require additional reinforcement such as the installation of plywood, approved insulation or cover board. Small timber protrusions and suitable decks may be treated directly, provided that the timber is of exterior quality, i.e. plywood. Fill joints flush with Sikaflex® sealant.
Paints and Coatings
Ensure the existing material is sound and firmly adhered. Remove any loose or degraded coatings. Ensure the surface is clean and free from oxidation, dust, dirt, and debris. Power wash and use biodegradeable non-sudsing detergent with clean water rinse as required.
Existing Sikalastic® System
The existing Sikalastic® System shall be soundly adhered to the substrate. Clean the membrane using a pressure washer at approximately 140bar (2000 psi) and biodegradeable non-sudsing detergent with clean water rinse. Allow to dry.
Sikaplan®/Sarnafil® Membranes
Clean the membrane using a pressure washer at approximately 140bar (2000 psi) and biodegradeable non-sudsing detergent with clean water rinse. Allow to dry.

No mixing necessary
 

Detailing
 

Non-structural Cracks Up To 1/16''
Detail application not necessary. Apply embedment/base resin layer per below. 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 seal with 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 Heavyor 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 instruction.
Transitions Between Dissimilar Materials
Apply 40–45 mil resin layer embedded with Sika® Flexitape Heavy or use Sika® Joint Tape SA centered over transitions or dissimilar materials. Apply embedment resin layer per instruction.
Embedment/Base Resin Layer With Sika® Reemat Reinforcement
Mixing not required. Apply Sikalastic®- 641 Lo-VOC at the coverage rate listed in the Sikalastic System Guide using 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. Place Sika® Reemat 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 Reinforcement
Mixing not required. Apply Sikalastic®- 641 Lo-VOC at the coverage rate listed in the Sikalastic System Guide 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 RoofPro 25 allow the first top resin layer to cure 12 hours at 70 °F and 50 % R.H. or until tack free before applying second top resin layer. On top of the complete RoofPro 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®- 641 Lo-VOC specified in the Sikalastic System Guide 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®- 641 Lo-VOC resin specified in the Sikalastic System Guide. Ensure there is an even and complete fleece saturation from the 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 roofing/waterproofing resin.
Seed and Back Roll Option
The Seed and Backroll option is primarily intended for use for maintenance traffic-type applications where enhanced slip resistance is required. Apply Sikalastic®- 641 Lo-VOC 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
The Full Broadcast and Seal option is intended for use for applications where both enhanced slip resistance and physical protection of the roofing membrane is required. Apply Sikalastic®- 641 Lo-VOC 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.