Sikalastic 641 Lo-VOC Vegetated Protected Membrane Roofing

Sikalastic 641 Lo-VOC Vegetated Protected Membrane Roofing is a Sika polyurethane roofing and waterproofing system for vegetated roofs. Its resin is Sikalastic-641 Lo-VOC, a single component, cold applied, moisture-triggered aliphatic polyurethane that is reinforced with either Sika Reemat fiberglass mat or Sika Fleece polyester fleece. The system is written up as CSI Section 07 55 63, Vegetated Protected Membrane Roofing.

The system covers a vegetated cold-fluid-applied polyurethane roofing and waterproofing build on structural concrete, plywood sheathing, cover board, metal or other substrates. Its scope includes substrate preparation and the bridging and sealing of air leakage and water intrusion pathways, including wall-to-roof air barrier connections and penetrations by piping, conduit and ducts. Related work sits in other sections: cast-in-place concrete (03 30 00), sheathing (06 16 00), flashing and sheet metal (07 60 00), elastomeric joint sealants (07 92 13) and roof drains (21 14 25). Soil and vegetation fall under Division 32, Exterior Improvements.

The membrane is intended to act as a continuous barrier against liquid water and to flash or discharge incidental water to the exterior. It is expected to carry an overburden made up of a drainage layer, optional insulation, growing media and vegetation, with optional hardscape, and it accommodates building movement at changes in substrate, perimeters and penetrations through accessory sealants. Sikalastic-641 Lo-VOC is also written into the Sikalastic Direct, Plaza and Recover systems and the Sikalastic 10, 15, 20 and 25 year builds for new construction and refurbishment.

Sikalastic-641 Lo-VOC is a low-odor, low-VOC saturating resin. It needs no mixing and is supplied ready to use. The chemical base is a single component, moisture-triggered aliphatic polyurethane.

• Packaging: 5 gal. (19 L) pail; a 50 gal drum is made to order in white and Standard Gray only.
• Colors: White, Standard Gray, Pearl Gray, Steel Gray, Mushroom and Copper Green, with custom colors available.
• Shelf life: 15 months in the 5 gal pail and 6 months in the 50 gal drum.
• Storage: dry, between 35 °F and 77 °F (2–25 °C); the material is conditioned to 50–77 °F (10–25 °C) before use.
• Density: 11.9 lb./gal. (1.4 kg/cm 3 as printed).
• VOC content: 38 g/l (ASTM D-2369-81).
• Solids by volume: 89 % (ASTM D-2697).

The resin is UV resistant and non-yellowing, resistant to ponding water, vapor permeable, abrasion resistant and chemical resistant. Chemical resistance covers paraffin, gasoline, fuel oil, white spirit, acid rain, detergents and moderate solutions of acids and alkalis. Some low molecular weight alcohols can soften it. A cradle-to-grave Environmental Product Declaration (EPD) is available for the product.

The published values below are for Sikalastic 20 builds, with Sika Reemat or Sika Fleece 140 as the reinforcement.

• Static puncture resistance: more than 55 lbf for both builds (ASTM D-751).
• Tensile strength: 1030 psi with Reemat and 900 psi with Fleece 140 (ASTM D-751).
• Elongation at break: 21 % with Reemat and 82 % with Fleece 140 (ASTM D-751).
• Tear strength: 300 lbf/in with Reemat and 200 lbf/in with Fleece 140 (ASTM D-624).
• External fire performance: Class A (ASTM E 108).
• Artificial aging: 5,000 hours under UV light with no cracking or crazing (ASTM C-1442).
• Service temperature: -22 to 176 °F (-30 to 80 °C), intermittent.

Solar reflectance values, listed by CRRC under ASTM C-1549, are 84 for White, 57 for Pearl Gray, 37 for Standard Gray, 12 for Steel Gray and 56 for Mushroom. Thermal emittance is 0.91 for each of those five colors (ASTM C-1371). The Solar Reflectance Index is 108 for White (ASTM E-1980). White Sikalastic-641 Lo-VOC is the version written up for cool roofs and solar roof assemblies.

The cured membrane is held to film requirements. It conforms to ASTM D7311-07, the standard for liquid applied, single component, moisture-triggered aliphatic polyurethanes used in roofing. The requirements include volume solids of 76 % minimum, weight solids of 83 % minimum, no sag at 700 micrometers (0.028 in.), tensile strength of 270 lb/in2 (1.86 MPa) minimum, elongation of 200 % minimum, and no cracking or checking after 5000 hours of accelerated weathering (ASTM G 154). Water vapor transmission is at most 8.5 g/m2/day (0.033 perm-inches) and indentation hardness is 82 durometer units plus or minus 5.

Sikalastic-641 Lo-VOC carries these approvals and standards: FM Approval Standard 4470 for Class 1 Roof Covers, UL 790 Class A, Miami-Dade, ASTM D 6083, ASTM E 108, ASTM C 836, CRRC, the Florida Building Code and ICC-ES ESR-4509.

For the vegetated system, FM Global compliance is written as FM Approval Standard 4470 for Class I roof covers on non-combustible substrates, with a Class 1-990 wind uplift rating, a hail rating of SH, and ASTM E-108-00 Class A at a slope of 1 in 12. A Cradle-To-Grave Life Cycle Analysis and an Environmental Product Declaration under ISO 14025:2006 are called for.

The system is built from a base layer of Sikalastic 641 Lo-VOC, a reinforcement and one or two top layers. Wet film thickness and approximate coverage for each Sikalastic RoofPro build in the vegetated system are listed below. The 10, 15, 20 and 25 year labels match the system warranty lengths written into the section.

• RoofPro 10 with Sika Reemat Standard: base 30 mils wet at 53 sf/gal, top 30 mils wet at 53 sf/gal.
• RoofPro 15 with Sika Reemat: base 50 mils wet at 32 sf/gal, top 20 mils wet at 80 sf/gal.
• RoofPro 15 with Sika Fleece 120: base 45 mils wet at 35 sf/gal, top 25 mils wet at 64 sf/gal.
• RoofPro 20 with Sika Reemat: base 50 mils wet at 32 sf/gal, top 30 mils wet at 53 sf/gal.
• RoofPro 20 with Sika Fleece 140: base 50 mils wet at 32 sf/gal, top 30 mils wet at 53 sf/gal.
• RoofPro 25 with Sika Reemat: base 50 mils wet at 32 sf/gal, then two top layers of 23 mils wet at 69 sf/gal each.
• RoofPro 25 with Sika Fleece 170: base 66 mils wet at 24 sf/gal, top 34 mils wet at 47 sf/gal.

A Metal Roof system guide uses a primer, a base layer of 20 mils wet at 80 sf/gal and a top layer of 20 mils wet at 80 sf/gal, with Sika Flexitape Heavy or Sika Joint Tape SA centered over seams, transitions and treated cracks and joints. Minimum dry film thickness is 36 mils for the metal roof build, 62 mils for Sikalastic 10 and 15 with Reemat, 71 mils for 20 and 85 mils for 25. With Fleece, the minimum dry film is 62 mils for 15, 71 mils for 20 and 89 mils for 25.

Sika Reemat is a conformable, random strand fiberglass mat. Sika Fleece is a non-woven, needle-punched polyester fleece. Sika Flexitape Heavy is a nylon mesh for local reinforcement at structural cracks, expansion joints and transitions between dissimilar materials, and Sika Joint Tape SA is a self-adhering rubberized tape with a woven polyester facer.

Sikaflex 11FC, a one-part polyurethane sealant, is used for fillet beads and penetrations. Sikaflex Hyflex 150 LM or Sikasil WS-295 finishes UV-exposed terminations. SikaFast 3341, a two-component methyl methacrylate adhesive, bonds the membrane to PVDF (Kynar) finished edge metal. SikaQuick 1000 and SikaQuick VOH are the cementitious repair mortars, and Sikadur-22 Lo-Mod or Sikalastic-720 fills uneven areas and birdbaths.

The priming guide assigns primers by substrate.

• Concrete and lightweight structural concrete: Sikalastic Concrete Primer Lo-VOC, DTE Primer, GDC Primer, EP Primer/Sealer or EP Primer Rapid.
• Cement and gypsum based roof boards, brick and stone: Concrete Primer Lo-VOC, EP Primer/Sealer or EP Primer Rapid.
• Bituminous substrates, PVC membranes, unglazed roof tiles, fiberglass, polyurethane foam, metals, painted and pre-coated surfaces, and wood: EP Primer/Sealer or EP Primer Rapid.
• TPO and EPDM: Sikalastic EPDM/TPO Primer Lo-VOC. Hypalon: Sika Bonding Primer.
• Green and damp concrete: Sikalastic GDC primer. Existing Sikalastic 600 Series membrane older than 7 days: Sika Reactivation Primer or Sika Concrete Primer Lo-VOC.

A drainage layer is the first component over the cured membrane. Sika Drainage Mat GRS is the layer written for vegetated roof assemblies. It has an impermeable, perforated, dimpled polystyrene core bonded to a root resistant non-woven polypropylene filter fabric on top and a non-woven polypropylene protection fabric underneath. The core is installed dimpled side down so that water is held in the cups, and excess water is collected and conveyed to a collection system.

Other mats in the section are Sika Drainage Mat 420 for soil, sand or stone ballast, Sika Drainage Mat 720 for light traffic up to 21,000 psf on freshly placed concrete or grout overburden, and Sika Drainage Mat 1000, a high density polyethylene geonet, for heavy traffic up to 40,000 psf.

Application takes place with ambient air between 41 °F (5 °C) and 95 °F (35 °C), relative humidity of 85 % or less and substrate temperature between 41 °F and 140 °F (60 °C). The substrate and uncured coating sit at least 5 °F (3 °C) above the dew point. Substrate moisture content is 4 % or less by Sika-Tramex meter. Opened containers form a film after about 1–2 hours at 75 °F and 50 % R.H. Materials are stored above 55 °F (12.6 °C) for at least 24 hours before application.

• Rain resistant after 1 hour at 40, 50 and 70 °F (50 % R.H.).
• Touch dry in 12 hours at 40 °F, 6 hours at 50 °F and 4 hours at 70 °F.
• Full cure in 24 hours at 40 °F, 18–24 hours at 50 °F and 12–18 hours at 70 °F.
• Minimum wait before overcoating: 18 hours at 40 °F, 8 hours at 50 °F and 6 hours at 70 °F. After 7 days the surface is cleaned and primed with Sika Concrete Primer Lo-VOC or Sika Reactivation Primer.

The membrane can proceed when rain is imminent and cures in immersion immediately after application. At a wet film thickness of 15–20 mils it serves as a temporary roofing and waterproofing barrier on a prepared deck. It is not intended for continuous contact with temperatures below -22 °F (-30 °C) or above 176 °F (80 °C), and continuous immersion is excluded such as fountains, ponds, pools and tank interiors. On-grade concrete decks, unvented metal pans, split or sandwich slabs with encapsulated membrane or insulation, cinder fill decks and lightweight insulating concrete overlays are not covered with Sikalastic systems without additional deck evaluation. Cementitious products such as tile mortar are not applied directly onto this resin; the Sikalastic-624 WP and Sikalastic-644 Lo-VOC resins are the ones named for that use.

Applicators install the vegetated build as a reinforced liquid-applied roofing membrane, working the resin with a 1/2 in. nap roller, brush, squeegee or spray.