Sikalastic-621 Vegetated Protected Membrane Roofing

Sikalastic-621 Vegetated Protected Membrane Roofing is the vegetated-roof build of the Sikalastic RoofPro family that uses Sikalastic-621 TC as its resin. The Sikalastic-621 roofing system pairs a cold applied, elastomeric, aliphatic, single component, moisture-triggered polyurethane resin with fiberglass mat or polyester fleece reinforcement to form a membrane and flashing system. It is CSI Section 07 55 63, Vegetated Protected Membrane Roofing.

RoofPro is a fully bonded, elastomeric membrane for concrete, plywood sheathing, cover board, metal substrates and modified bitumen roofing membranes. It goes down as a 1 ply, fully reinforced, self-flashing membrane that is waterproof immediately after application. The section calls for a vegetated cold-fluid-applied polyurethane roofing and waterproofing system, including substrate preparation and the sealing of air and water pathways at wall-to-roof connections and at pipe, conduit and duct penetrations.

The membrane receives an overburden of drainage layer, optional insulation, growing media and vegetation, and optional hardscape. Sikalastic-621 TC also serves as the embedment and top coat resin for Sikalastic Built Up, Direct, Plaza Deck/PMA, Vegetated and Recover systems, in 10, 15, 20 and 25 year builds, for new construction and refurbishment.

Sikalastic-621 TC is the saturating resin for Sikalastic systems reinforced with Sika Reemat or Sika Fleece. It is a cold applied resin that needs no heat or flame. The resin is root resistant and recoatable, so a renewed system does not need stripping.

• Chemical base: single component, moisture-triggered, aliphatic polyurethane.
• Packaging: 5 gal. (19 L) pail.
• Colors: White, Pearl Gray and Steel Gray, with custom colors available above a minimum order quantity.
• Shelf life: 9 months.
• Storage: dry, 35 °F to 77 °F (2–25 °C), with conditioning to 50–77 °F (10–25 °C) before use.
• Density: about 12 lb./gal. (about 1.44 kg/l) at 73 °F (23 °C).
• VOC content: 183 g/l (ASTM D-2369-81).
• Solids by volume: 81 % (ASTM D-2697).

The listed standards are ASTM E 108, ASTM D 6083 and ASTM C 836. White Sikalastic-621 is highly reflective and is written up for cool roofs and solar roof assemblies. With supplemental aggregated surfacing it also serves balconies, terraces, walkways and plazas exposed to foot traffic.

The cured film is held to ASTM D7311-07, the standard for liquid applied, single component, moisture-triggered aliphatic polyurethanes used in roofing. Viscosity falls between 5 and 20 Pa.s (ASTM D2196). Volume solids are 76 % minimum and weight solids 83 % minimum. The wet film shows no sag at 700 micrometers (0.028 in.).

• Tensile strength: 270 lb/in2 (1.86 MPa) minimum (ASTM D412).
• Elongation: 200 % minimum (ASTM D412).
• Accelerated weathering, 5000 hours: no cracking or checking (ASTM G 154).
• Water vapor transmission: 8.5 g/m2/day maximum, 0.033 perm-inches (ASTM E96).
• Tear resistance: 33 lbf/in (5.8 kN/m) minimum.
• Indentation hardness: 82 durometer units, plus or minus 5 (ASTM D2240).
• Static puncture resistance: 45.5 lbs (20.7 kg) minimum (ASTM D5602).
• Mandrel bend: passes with no cracking or flaking (ASTM D522).

The membrane resists gasoline, paraffin, fuel oil, mineral spirits, acid rain, detergents and moderate solutions of acids and alkalis. Some low molecular weight alcohols soften it. It is not intended for constant exposure below -22 °F (-30 °C) or above 176 °F (80 °C).

FM Global compliance for the vegetated system is written as FM Approval Standard 4470 for Class I roof covers on non-combustible substrates, 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. The membrane is non-flammable and complies with the VOC regulations of the state of installation.

Each Sikalastic RoofPro build pairs a base embedment layer with a reinforcement and one or two top layers of Sikalastic 621 TC. Thicknesses are wet film; coverage is approximate.

• RoofPro 10 with Sika Reemat Standard: base 35 mils at 45 sf/gal, top 30 mils at 53 sf/gal.
• RoofPro 15 with Sika Reemat: base 45 mils at 35 sf/gal, top 30 mils at 43 sf/gal.
• RoofPro 15 with Sika Fleece 120: base 45 mils at 35 sf/gal, top 30 mils at 53 sf/gal.
• RoofPro 20 with Sika Reemat: base 45 mils at 35 sf/gal, top 30 mils at 53 sf/gal.
• RoofPro 20 with Sika Fleece 140: base 50 mils at 32 sf/gal, top 35 mils at 45 sf/gal.
• RoofPro 25 with Sika Reemat: base 45 mils at 35 sf/gal, then two top layers of 30 mils at 53 sf/gal.
• RoofPro 25 with Sika Fleece 170: base 60 mils at 26 sf/gal, top 40 mils at 40 sf/gal.

The 10, 15, 20 and 25 labels correspond to the system warranty lengths listed in the section, and the materials warranty runs a minimum of one year from the date of Substantial Completion. Installers hold written authorization from the manufacturer to install the system.

Sikalastic-621 TC is rolled with a 1/2 in. nap phenolic resin core roller. It can also be applied by squeegee or spray, in which case it is backrolled. In the 25 year build the first top layer cures for 12 hours at 70 °F and 50 % R.H., or until tack free, before the second top layer goes on. Further resin layers carrying aggregate are applied within 7 days; past that window the surface is cleaned with non-sudsing detergent and rinsed, then primed with Sika Reactivation Primer.

With Sika Fleece, two-thirds of the resin goes onto the primed substrate first. The fleece is laid into the wet resin with seams overlapping a minimum of 3 in. along the edge and 6 in. end-to-end, a wet roller saturates it from the top, and the remaining one-third of the resin follows immediately.

Aggregated surfacing is required where direct foot traffic occurs and is applied in a supplemental resin layer, not into the top layer of the membrane. In the seed and back roll option, 15 mils wet of Sikalastic-621 TC is seeded with kiln-dried, iron-free aggregate and back rolled. In the full broadcast and seal option the same 15 mils is broadcast to rejection, the excess is removed after cure and a further resin coat seals it. The aggregate is clean, oven-dried quartz sand of at least 6.5 Mohs hardness, rounded or semi-angular, in 16–30 or 20–40 mesh.

Sikalastic-621 TC carries the limits below.

• The resin is not thinned with solvents.
• Concrete is at least 28 days old and the substrate is dry, with no frost, standing water or dampness.
• Moisture vapor transmission during application and cure is checked by ASTM D 4263 (polyethylene sheet method).
• On substrates that outgas, application is made while ambient and substrate temperatures are falling; applied during rising temperature, pinholing or blistering may occur.
• Indoor use needs sufficient air flow and ventilation to keep odors and vapors from leaving the work area.
• On-grade concrete decks are not covered with RoofPro systems.
• Continuous immersion and application over ceramic tile are outside its use.

Application can proceed when precipitation is imminent, and the membrane cures in immersion directly after application. Ambient and substrate temperatures are above 41 °F (5 °C), and surfaces are free of visible water, dew, frost, snow and ice.

Sika Reemat is a conformable random strand fiberglass mat, and Sika Fleece is a non-woven needle-punched polyester fleece. Local reinforcement uses Sika Flexitape Heavy, a nylon mesh, or Sika Joint Tape SA, a self-adhering polymeric rubberized tape. Sikaflex 11FC fills fillet beads and penetrations; Sikaflex Hyflex 150 LM or Sikasil WS-295 finishes exposed terminations. SikaFast 3341 is the MMA adhesive for PVDF (Kynar) finished edge metal.

Primers named for this system include Sika Concrete Primer Lo-VOC, Sikalastic EP Primer/Sealer and EP Primer Rapid, Sika Bonding Primer (water-based), Sikalastic GDC primer for green and damp concrete and plywood, Sikalastic EPDM and EPDM/TPO Lo-VOC for flexible roofing membranes, and Sikalastic Conductive Primer for dry leak detection. Sika Reactivation Primer is the over-coating primer for existing systems. SikaQuick 1000 and SikaQuick VOH repair concrete, and Sikadur-22 Lo-Mod or Sikalastic-720 fill birdbaths.

Sika Drainage Mat GRS is the perforated polystyrene drainage layer for vegetated assemblies, installed dimpled side down. It is bonded to a root resistant polypropylene filter fabric. Sika Drainage Mat 720 and 1000 are named for freshly placed concrete or grout overburden, at light traffic up to 21,000 psf and heavy traffic up to 40,000 psf. The concrete pavers in the section have compressive strength above 7,000 psi, flexural strength above 600 psi and water absorption of 5 % or less, with freeze/thaw loss under 1 % by dry weight over 50 cycles (ASTM C67). Applicators place this system as a reinforced liquid-applied membrane under the planted overburden.