Sikalastic-624 WP Fluid-Applied Protected Membrane Roofing

Sikalastic-624 WP Fluid-Applied Protected Membrane Roofing is the protected-membrane roofing build that uses Sikalastic-624 WP, an alkaline resistant, single component polyurethane saturating resin. It is CSI Section 07 55 56, Fluid-Applied Protected Membrane Roofing, and its builds carry the Sikalastic RoofPro WP names.

The section provides a protected cold-fluid-applied polyurethane roofing and waterproofing system on structural concrete, plywood sheathing, cover board, metal or other substrates. The membrane is a continuous barrier against liquid water that discharges incidental water to the exterior, and it is intended to receive an overburden of insulation and ballast or concrete pavers. Sealants take up movement at substrate changes, perimeters and penetrations, and the installed system withstands design pressures calculated under the current revision of ASCE 7.

The resin goes down as a fully bonded, 1 ply, fully reinforced, self-flashing liquid-applied roofing membrane that is waterproof immediately after application.

Sikalastic-624 WP is a cold applied, elastomeric, aliphatic, single component, alkaline resistant, moisture-triggered polyurethane resin. It is the embedment and top resin for Sikalastic-624 systems reinforced with Sika Reemat and the saturating resin for systems reinforced with Sika Fleece.

Its uses are Sikalastic waterproofing systems direct to substrate, including decks, plaza deck and PMA assemblies, amenity decks and fountain walls, for new construction and refurbishment. It is also used for split-slab waterproofing between slabs 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. Alkaline resistance suits it to use under tile.

• Chemical base: single component, moisture-triggered aliphatic polyurethane.
• Packaging: 5 gal. (19 L) pail.
• Colors: White and Pearl Gray.
• Shelf life: 9 months.
• Storage: dry between 35 °F and 77 °F (2–25 °C), conditioned to 50–77 °F (10–25 °C) before use.
• Density: 10.8 lb./gal. (1294 kg/m3).
• VOC content: 209 g/l (ASTM D-2369-81).
• Solids by volume: 71 % (ASTM D-2697).

The approvals and standards are Miami Dade, ASTM C836, ASTM E-108 and the Florida Building Code.

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: 2450 psi with Reemat and 1100 psi with Fleece 140 (ASTM D-751 Procedure B).
• Elongation at break: 10 % with Reemat and 78 % with Fleece 140 (ASTM D-751).

Film requirements for the cured membrane follow ASTM D7311-07. Volume solids are 76 % minimum and weight solids 83 % minimum in this section. Tensile strength is 270 lb/in2 (1.86 MPa) minimum and elongation 200 % minimum. Water vapor transmission is 8.5 g/m2/day maximum (0.033 perm-inches), tear resistance 33 lbf/in (5.8 kN/m) minimum, indentation hardness 82 durometer units plus or minus 5, and static puncture resistance 45.5 lbs (20.7 kg) minimum. Accelerated weathering for 5000 hours (ASTM G 154) causes no cracking or checking, and the mandrel bend (ASTM D522) passes with no cracking or flaking.

Builds are 15, 20 and 25 year systems, each with a Reemat and a Fleece version. Layer thicknesses are wet film and coverage is approximate.

• RoofPro WP 15 with Sika Reemat: base 45 mils at 35 sf/gal, top 30 mils at 53 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 40 mils at 40 sf/gal.
• RoofPro WP 20 with Sika Fleece 140: base 50 mils at 32 sf/gal, top 35 mils at 45 sf/gal.
• RoofPro WP 25 with Sika Reemat: base 45 mils at 35 sf/gal, two top layers of 30 mils at 53 sf/gal.
• RoofPro WP 25 with Sika Fleece 170: base 65 mils at 24 sf/gal, top 40 mils at 40 sf/gal.

Minimum dry film thickness with Reemat is 53 mils for the 15 year build, 60 mils for the 20 year build and 75 mils for the 25 year build. With Fleece it is 50, 60 and 75 mils. A modified bitumen surface under the Fleece 140 twenty-year build could reach about 14–16 sf/gal over the full system, and a Reemat base coat 25–28 sf/gal. Flexitape Heavy or Joint Tape SA is centered over seams, transitions and treated cracks.

The protected build can sit on cover board or thermal barrier at least 1/2 in. thick. Named boards are Dens-Deck Prime (Georgia-Pacific), Securock Gypsum Board and Securock Cement Board (United States Gypsum). Screws for steel decks pass through the deck by at least 3/4 in., screws for wood decks reach 1 in. or pass through by 1/4 in., and screws or drive spikes for concrete decks reach 1 in. after predrilling. All use 3 in. diameter Galvalume plates from Sika Sarnafil. Sarnacol OM Board Adhesive is the low-rise urethane foam adhesive.

Sika Drainage Mat 420 serves soil, sand or stone ballast. Sika Drainage Mat 720 is rated for light traffic up to 21,000 psf over fresh concrete or grout, and Sika Drainage Mat 1000, a high density polyethylene geonet, for heavy traffic up to 40,000 psf. Sika Drainage Mat GRS, a perforated dimpled polystyrene core with root resistant filter fabric, is the vegetated-assembly layer. Extruded polystyrene insulation is Sika Sarnatherm XPS to ASTM C578 Type VI (40 psi), VII (60 psi) or V (100 psi), and Sika 120 Fleece, a 3 oz./sq.yd. polyester mat, separates it from the overburden.

Concrete, cover boards and cementitious substrates take Sika Concrete Primer Lo-VOC or Sikalastic Primer EP and EP Rapid. Sika Bonding Primer is water-based. Sikalastic GDC primer is for green and damp concrete and plywood. Sikalastic EP Primer/Sealer primes metal and PVC membranes, and EPDM and TPO roofing takes a rubber polymer-based primer. SikaFast 3341 bonds the membrane to PVDF (Kynar) finished edge metal. Fillet beads use Sikaflex 11FC, and exposed terminations Sikaflex Hyflex 150 LM or Sikasil WS-295. SikaQuick 1000 and SikaQuick VOH repair concrete, and Sikadur-22 Lo-Mod or Sikalastic-720 fills birdbaths.

A 15–20 mil wet film serves as a temporary barrier and can stay under the finished system after a RoofPro primer is applied to the deck. System warranty lengths are 15, 20 and 25 years, with a materials warranty of at least one year from Substantial Completion.