Sikalastic-644 Lo-VOC Fluid-Applied Protected Membrane Roofing

Sikalastic-644 Lo-VOC Fluid-Applied Protected Membrane Roofing is a protected-membrane roofing system in which Sikalastic-644 Lo-VOC resin is reinforced with Sika Reemat or Sika Fleece and covered by an overburden. It is CSI Section 07 55 56, Fluid-Applied Protected Membrane Roofing, and falls within the Sikalastic RoofPro WP family of builds.

The section covers a protected cold-fluid-applied polyurethane roofing and waterproofing system on structural concrete, plywood sheathing, cover board, metal or other substrates. Work includes substrate preparation and the sealing of air leakage and water intrusion pathways, including wall-to-roof air barrier connections and penetrations by piping, conduit and ducts. Concrete (03 30 00), sheathing (06 16 00), flashing and sheet metal (07 60 00), joint sealants (07 92 13) and roof drains (21 14 25) are specified in their own sections.

The system works as a continuous barrier against liquid water and discharges incidental water to the exterior. The membrane receives an overburden of insulation and ballast or concrete pavers, and accessory sealants take up movement at changes in substrate, perimeters and penetrations. The installed system withstands the design pressures calculated under the current revision of ASCE 7. As a reinforced liquid-applied roofing membrane, it is applied in place and fully adhered to the deck.

Sikalastic-644 Lo-VOC is a cold applied, highly elastic, aliphatic, single component, alkali resistant, moisture-triggered polyurethane elastomeric resin with low odor and low VOC content. It needs no mixing. It is the embedment and top resin for Reemat-reinforced systems and the saturating resin for Fleece-reinforced systems.

Its listed uses are decks, plazas, amenity decks and foundation walls applied direct to the substrate, new construction and refurbishment, cementitious overlays and tile mortar, split-slab waterproofing on zero slope decks, vegetated deck waterproofing, plaza decks with concrete pavers or with asphalt or concrete paving stones in a sand bed, waterproofing under tile in a mortar bed, cementitious and asphalt pavement overlays, and waterproofing around and beneath mechanical equipment. Vertical surfaces carry no height limit. The alkali resistance suits it to use under tile.

• Packaging: 5 gal. (19 L) pails and 50 gal. drums.
• Colors: White and Standard Gray, with custom colors above a minimum order quantity.
• Shelf life: 15 months in a 5 gal pail and 6 months in a 50 gal drum.
• Storage: dry between 35 °F and 77 °F (2–25 °C), conditioned to 50–77 °F (10–25 °C) before use.
• Density: 11.76 lb./gal.
• Solids by volume: 80.25 % (ASTM D-2697).
• Service temperature: -22 to 176 °F (-30 to 80 °C), intermittent.

The approvals and standards for the resin are Miami Dade, the Florida Building Code, UL 790 Class A, ASTM D-6083 and Cool Roof Rating Council (CRRC) listing. Two tile standards also apply: ANSI A118.10 for load bearing thin-set ceramic tile and stone, and ANSI A118.12 for crack isolation under thin-set ceramic tile and stone. External fire performance is UL 790 Class A (ASTM E 108). A cradle-to-grave Environmental Product Declaration (EPD) is available.

Mechanical values are published for Sikalastic 20 builds with Sika Reemat and with Sika Fleece 140.

• Static puncture resistance: more than 55 lbf for both builds (ASTM D-5602).
• Tensile strength: 1030 psi with Reemat and 900 psi with Fleece 140 (ASTM D-751 Procedure B).
• Tear strength: 300 lbf/in with Reemat and 200 lbf/in with Fleece 140 (ASTM D-624).

Reflectance and emittance are published by CRRC under ASTM D7897-18. White has an initial solar reflectance of 0.87 and a rapid rating of 0.87. Standard Gray has a rapid rating of 0.33. Thermal emittance is 0.92 initial for White, 0.91 rapid for White and 0.91 rapid for Standard Gray. The Solar Reflectance Index of White is 110.

The cured film conforms to ASTM D7311-07. Required values include a VOC content under 50 g/l, volume solids of 76 % minimum, weight solids of 83 % minimum, tensile strength of 270 lb/in2 (1.86 MPa) minimum, elongation of 200 % minimum, tear resistance of 33 lbf/in (5.8 kN/m) minimum, indentation hardness of 82 durometer units plus or minus 5, and static puncture resistance of 45.5 lbs (20.7 kg) minimum. The film shows no cracking or checking after 5000 hours of accelerated weathering (ASTM G 154) and passes the ASTM D522 mandrel bend.

Three warranty-length builds, each with a Reemat and a Fleece variant, are written for the protected system. Layer thicknesses are wet film and coverage rates are approximate.

• RoofPro WP 15 with Sika Reemat: base 45 mils at 35 sf/gal, top 25 mils at 64 sf/gal.
• RoofPro WP 15 with Sika Fleece 120: base 45 mils at 35 sf/gal, top 25 mils at 64 sf/gal.
• RoofPro WP 20 with Sika Reemat: base 45 mils at 35 sf/gal, top 30 mils at 53 sf/gal.
• RoofPro WP 20 with Sika Fleece 140: base 50 mils at 32 sf/gal, top 25 mils at 64 sf/gal.
• RoofPro WP 25 with Sika Reemat: base 45 mils at 35 sf/gal, two top layers of 25 mils at 64 sf/gal each.
• RoofPro WP 25 with Sika Fleece 170: base 60 mils at 27 sf/gal, top 35 mils at 45 sf/gal.

Minimum dry film thickness is 56 mils for the 15 year builds, 60 mils for the 20 year builds and 76 mils for the 25 year builds, with either reinforcement. Flexitape Heavy or Joint Tape SA is centered over seams, transitions and treated cracks and joints in every build. The materials warranty runs a minimum of one year from Substantial Completion, and the system warranty lengths are 15, 20 and 25 years.

Three cover boards, each at least 1/2 in. thick and intended as a thermal barrier directly over a structural wood or steel deck, are named: Dens-Deck Prime (glass-faced, treated gypsum core) from Georgia-Pacific, Securock Gypsum Board (fiber-reinforced, treated gypsum core) and Securock Cement Board (glass-faced, cementitious core) from United States Gypsum.

Fasteners are #12 or #14 screws for steel and wood decks and #14 screws or drive spikes for concrete decks. Screws pass through a steel deck by at least 3/4 in., reach 1 in. into a wood deck or pass through it by at least 1/4 in., and reach 1 in. into concrete, which is predrilled. Each is installed with a 3 in. diameter Galvalume plate, and fasteners and plates are supplied by Sika Sarnafil. Low-rise Sarnacol OM Board Adhesive is the urethane foam adhesive option. Fasteners and adhesive meet Factory Mutual requirements.

Sika Drainage Mat 420 is an impermeable dimpled polypropylene core heat-bonded to non-woven polypropylene filter fabric on top and polyethylene protection film underneath, for soil, sand or stone ballast. Sika Drainage Mat 720 and Sika Drainage Mat 1000 serve freshly placed concrete or grout overburden. Mat 720 is rated for light traffic up to 21,000 psf, and Mat 1000, a high density polyethylene geonet, for heavy traffic up to 40,000 psf. Sika Drainage Mat GRS covers vegetated roof assemblies.

A membrane applied at 15-20 mils wet film can serve as a temporary roofing barrier on a prepared deck and stays in place under the finished system. A Sikalastic RoofPro primer is applied to the deck first, and Sika Reactivation Primer or Concrete Primer Lo-VOC goes between the temporary layer and the final system.