CTG-4.5xE — Acrylic-surfaced reinforced roof system

CTG-4.5xE is Western Colloid specification CTG-4.5xE, a white elastomeric reflective coating system for a cap sheet or smooth surface, either new or upgrade, with an acrylic surface. The revision date printed on it is 03/21. It is part of the Western Cool Roof Systems group and is classed as a commercial roof coating system for commercial roof restoration.

The 4.5 in the code is the ElastaHyde rate, 4.5 gallons per 100 square feet, which is the heaviest rate in the CTG series. The system is a cold process method for putting a reflective acrylic surface on existing or new smooth-surface roofing. It can also re-coat existing spray polyurethane foam roofs. It is water based with very low odor, and it upgrades a new or existing built-up or modified bitumen roof to California Title 24 standards.

For built-up and modified bitumen roofs in a cool roof coating scope, the single-material assembly keeps the system to one coating.

The assembly has one component, white acrylic ElastaHyde at 4.5 gallons per 100 square feet. Its approximate dry weight is 31.5 lb per 100 square feet, which is also the total system dry weight. The total system dry thickness is approximately 38 mils.

Supporting materials used with it are #800 Elastic Cement, stitchbonded polyester fabric, #8000 All Weather Elastic Cement, #970 A2A Bonding Primer and #850 SWS walkway coating.

This assembly meets UL Class A, Factory Mutual, California Title 24, LEED (USGBC) and ENERGY STAR criteria. The publications it refers to are ASTM, Underwriters Laboratories, Factory Mutual (FM Global), Western Colloid details, drawings and notes, ENERGY STAR roof coating guidelines, CRRC, California Title 24 and LEED.

A ten year manufacturer warranty covering material and labor (NDL) is part of the requirements in this version, alongside a 2 year contractor warranty on materials and workmanship.

• Polyester fabric is a 2.75 ounce firm or 3.0 ounce soft stitchbonded fabric for reinforcing asphalt emulsion, acrylic coating and flashing materials. It comes in several widths.
• #850 SWS walkway coating is a water-based acrylic coating with an aggregate that forms a textured, non-slip, abrasion-resistant surface on smooth and coated roofs.
• #8000 All Weather Elastic Cement is a solvent-based white sealant for asphalt built-up roofing, modified bitumen, metal and single-ply roofs including EPDM, PVC, TPO and Hypalon. It sets metal flanges and sheets where a water-based sealant is not practical.
• #800 Elastic Cement is a water-based acrylic resinous plastic emulsion with inert mineral pigments and fillers, white or black. It goes on exposed terminations, metal joints and drain sumps.
• #970 A2A Bonding Primer is a water-based clear acrylic primer for adhesion of acrylic coatings to smooth asphalt products.
• ElastaHyde #720 ARC is the base coat and the finish coat of the system.

The existing membrane is repaired until it is sound and watertight before any coating. Loose gravel, dirt, dust and debris are removed by vacuum, sweeping or power blower, and the whole roof is washed, with attention to valleys and ponding areas.

Small splits are repaired by a three-course method with #800: 5 gallons per 100 square feet (about 1/8 inch), one embedded ply of polyester brushed in, then another coat at 4 gallons per 100 square feet. Pipe flashings, cones, exposed metal joints and flanges get #800 with polyester fabric in the same way. Corners at curbs and skylight flashings, and any area repaired with roofing mastic, also receive #800.

Areas around drains and scuppers receive a ply of polyester fabric set in ElastaHyde. Valleys, waterways and any place where water ponds for more than 48 hours get an extra ply that extends 12 inches beyond the ponding area or the drain sump, set into ElastaHyde at 3 gallons per 100 square feet. This work comes before the final coats.

Smooth asphalt or non-granulated modified bitumen needs #970 A2A primer before ElastaHyde; granulated surfaces do not. The roof is washed to remove asphaltic residue that can cause poor adhesion or tobacco staining, and primer is applied over the whole roof at 1/2 gallon per 100 square feet. It is mixed well, strained if sprayed, and not thinned.

The coating goes on in three coats of ElastaHyde, each at 1 1/2 gallons per 100 square feet, with 24 hours of drying between coats. Coats are cross-hatched at right angles. Coating is done early in the day, before the emulsion surface heats and softens, and stops if the surface turns soft and sticks to equipment or feet.

Where a protected or non-slip surface is wanted, #850 SWS is rolled on at 2 gallons per 100 square feet with a short-nap or smooth roller. A second coat of 2 gallons per 100 square feet goes on after at least 24 hours, optionally at a right angle to the first for a different surface pattern. At roof doors, hatches and equipment service doors, a reinforcing layer is added first: a polyester ply broomed into a 2 gallon coat of #850 SWS and dried for at least 24 hours.

Published values for white ElastaHyde #720 ARC include initial solar reflectance of 84% (ASTM C1549), initial thermal emittance of 89% (ASTM C1371), SRI of 106 initially and 93 aged, and Class A under UL 790 and ASTM E108. Elongation is above 250% initially, tensile strength is above 250 psi, and permeance is below 15 (ASTM D1653). The CRRC product ID is 0682-003. Recommended dry thickness is 24 mils or more, with a 20 mil minimum. Coverage is 75 to 100 square feet per gallon per coat. Application temperature is 50 to 100 degrees F ambient.

Coating colors other than white include Platinum Gray (CRRC 0682-004) and California Tan (CRRC 0682-005), all three meeting ENERGY STAR guidelines.