07 56 00 Fluid-Applied Roofing Recover Sikalastic-515

Sikalastic-515 AC is a single-component, cold fluid-applied acrylic roof coating made by Sika Corporation. It is a 100% acrylic elastomeric coating classed as ASTM D6083 Type I. The 07 56 00 Fluid-Applied Roofing Recover system built around it is written for structural concrete, metal, modified bitumen and single-ply roofing membranes. The coating is fully bonded to the roof and is installed partially reinforced.

The coating is used to extend the life of existing roofs, to recover them, and to raise their solar reflectivity. It is also used to reinforce and waterproof roof seams, penetrations, vertical transitions and terminations, and to make spot repairs. Its color is white.

The system is intended to perform as a continuous barrier against liquid water and to flash or discharge incidental water to the exterior. It remains exposed. It accommodates building movement at changes in substrate, perimeters and penetrations by means of accessory sealants. The installed system does not permit the passage of water.

The work includes substrate preparation and the bridging and sealing of air leakage and water intrusion pathways, including the connections of walls to the roof air barrier and penetrations such as piping, conduit and ducts. Concrete, sheathing, flashing and sheet metal, elastomeric joint sealants and roof drains belong to other specification sections.

• Packaging: 5 gal. pail.
• Color: white.
• Shelf life: 12 months, stored in a dry place between 40°F and 80°F away from moisture, heat, sparks and open flames.
• Viscosity: 110 KU (ASTM D562).
• Solids by mass: 69% (ASTM D1644). Solids by volume: greater than 52% (ASTM D2697).
• Tensile strength: 250 ± 50 psi (ASTM D2370).
• Elongation at break: 180 ± 50% initial and 100 ± 20% after accelerated weathering.
• Tear strength: 90 pli (ASTM D624).
• Low temperature bend: pass 1/2 in. at -15°F (ASTM D522).
• Permeability to water vapor: 25 perms (ASTM D1653).
• Water absorption: 9% water swelling (ASTM D471).
• Behavior after artificial weathering: no cracking or checking after 1000 hours (ASTM D4798).
• Microbiological resistance: 0, no growth (ASTM G21).
• Adhesion in peel: 2 pli for SPUR, wet adhesion (ASTM C749, D903). Wet adhesion is obtained with a primer.

For the white coating, solar reflectance is 0.83 initial and 0.69 at three years (ASTM C1549). Thermal emittance is 0.90 initial and 0.91 at three years (ASTM C1371). Solar Reflectance Index is 104 initial and 86 at three years (ASTM E1980).

The product meets ASTM D6083 Type I and is California Title 24 compliant. It is CRRC listed. The coating is non-flammable and VOC compliant. It is not intended to be exposed to or in contact with a constant temperature below -15°F (-26°C) or above 176°F (80°C).

The coating is applied at 24 wet mils, which is 1.5 gal per 100 SF. The maximum application rate is 32 wet mils, or 2 gal per 100 SF. Three system lengths are defined, each with its own coat sequence.

• 10 year system: base coat and top coat, each at 24 wet mils (1.5 gal/100 SF). Dry film thickness is 26 mils.
• 15 year system: base coat and intermediate coat at 24 wet mils each, plus a top coat at 16 wet mils (1.0 gal/100 SF). Dry film thickness is 34 mils.
• 20 year system, metal roofs only: base, intermediate and top coats, each at 24 wet mils (1.5 gal/100 SF). Dry film thickness is 39 mils.

The guide specification provides for a manufacturer's standard material, or material and labor, warranty. The materials warranty runs at least one year from Substantial Completion, and system warranties run 10, 15 or 20 years by system length. Rough, irregular or granulated surfaces can need additional coating to reach the minimum dry film thickness.

Acceptable substrates include concrete, concrete block, most bituminous surfaces, EPDM, PVC and TPO single-ply membranes, and metal. Bituminous surfaces cover asphalt, bituminous coatings, and granulated or smooth SBS cap sheets. The presence of volatiles in bituminous surfaces can discolor the coating if it is not primed. Metal surfaces include aluminum, galvanized steel, cast iron, copper, lead, brass, stainless steel and zinc.

Four Sikalastic primers are matched to substrates:

• Sikalastic 501 Primer for metal, modified bitumen and built-up roofing, and as a rust inhibitor. Applied at 12 to 16 mils (0.75 to 1.0 gal per 100 SF), it also blocks bleed-through from mineral cap sheets, modified bitumen and other asphalt surfaces.
• Sikalastic 502 Primer for concrete, metal and old polyurethane.
• Sikalastic 503 Primer for PVC and TPO.
• Sikalastic 504 Primer for EPDM and Hypalon.

An adhesion test (ASTM D903) precedes coating. On EPDM, primer is typically preceded by a thorough wash and is scrubbed in with a 3M pad. Exposed metal drain bowls and pipes are power tool cleaned (SSPC SP-3) to bright metal and solvent wiped before primer.

Surfaces are pressure washed at 2,000 to 2,500 psi. Oil, grease and animal fats are removed with tri-sodium phosphate and water. Substrate moisture content is 4% or less as measured with a Tramex moisture meter, and wet insulation is removed and replaced. Cracks and voids wider than 0.040 in. are routed and caulked with polyurethane sealant. At inside corners and deck-to-penetration junctions a fillet bead of polyurethane sealant at least 3/4 in. is installed. Moving cracks and joints between dissimilar materials receive a bond break tape at least 1 in. wide.

Detail reinforcement uses Sika Flexitape Heavy, a nylon mesh for structural cracks, expansion joints and transitions between dissimilar materials, or Sika Joint Tape SA, a self-adhering polymeric rubberized tape with a woven polyester facer. Reinforcement strips are at least 3 in. wide and are embedded in Sikalastic-515 AC or Sikalastic-515 FG. Horizontal-to-vertical transitions get a 3/4 in. by 3/4 in. Sikaflex polyurethane sealant cant. Sikaflex-11 FC is the fillet bead and penetration sealant where it is not exposed to UV light. Sikaflex-1a or Sikasil WS-295 is used where the sealant stays exposed. On standing seam metal roofs, Sikalastic-515 FG with Sika Flexitape Heavy seals the seams.

The coating is mixed in 5 gal. pails with a variable speed drill and jiffy mixer for about 3 minutes. It can be applied by brush, roller or airless spray. The data sheet sets application above 50°F with substrate temperature at least 5°F above the dew point; the guide specification text sets application above 41°F (5°C). Drying time is 4 to 6 hours depending on temperature and humidity. Detail coats cure before the base coat, and the base coat cures before the top coat.

Base and intermediate coats are back rolled for uniform coverage. Back rolling the top coat is needed only on an unusually rough surface. Foot traffic is kept off the finished coating for at least 48 hours at 75°F and 50% R.H. Walkway pads are used where the roof carries foot traffic, and their edges are caulked with Sikalastic-515 FG.

At drains, the bowl opening is blocked, the strainer basket and clamping ring are removed, and the liquid coating and reinforcement extend into the throat of the drain. Metal flanges are encapsulated between coating layers. Terminations occur in raked-out mortar joints, saw cut joints or under counterflashing, and are sealed with Sikaflex-11 FC and a top coat of Sikalastic-515 AC or Sikasil WS-295.

The coating is applied by professionally trained applicators. It is not intended for ponding water beyond 72 hours, and tile or topping slabs are not applied on it. Areas prone to ponding are resloped. Metal roof projects that require a warranty are preinspected by a Sika representative for seam detailing. The system fits the acrylic coating of metal roofs as well as the other substrates listed above.