SM-Rib Metal Roofing

SM-Rib is an exposed-fastener metal roofing panel from the Gibraltar Building Products Building Accessories Division. It is formed as a roof and wall panel and is specified under Section 07410, preformed roof and wall panels. The same profile is used for roofing, mansard, soffit and equipment screen applications.

Each panel covers 36 inches. The rib stands 3/4 inch high, and the ribs repeat every 9 inches. The panel style is a sidelap seam with exposed fasteners, the same construction used for metal roof replacement with exposed-fastener panels. The minimum slope is 3:12.

Panels are custom cut to the inch. The line also includes a wide variety of colors for both panels and flashings, a complete line of accessories and technical support.

The profile is a 3/4 inch rib at 9 inch spacing across a 36 inch coverage width. The texture is smooth between the ribs.

The side lap carries an anti-siphon channel. The channel sits in the lap where one panel overlaps the next, and the fastener passes through the lap at the rib. Fastening through the sidelap seam gives the exposed-fastener system its single, repeatable attachment line.

• Coverage: 36 inches
• Rib height: 3/4 inch
• Rib spacing: 9 inches on center
• Style: sidelap seam, exposed fastener
• Minimum slope: 3:12
• Lengths: custom, cut to the inch

SM-Rib is made in 26 gauge and 29 gauge. Both gauges are produced at the Jacksonville, Florida plant of SEMCO.

The base metal is one of three steel sheets:

• Galvalume steel sheet, AZ50, conforming to ASTM A792, for all panels
• Galvanized steel sheet, G90, conforming to ASTM A446, for unpainted panels
• Galvanized steel sheet, G60, conforming to ASTM A446, for painted panels

Two finishes are offered: silicone modified polyester (SMP) paint and bare mill-finished Galvalume. The SMP paint carries a 40-year warranty. Acrylic coated Galvalume in the mill finish carries a 25-year warranty.

Galvalume is an aluminum-zinc alloy coating of 55% aluminum, 43.4% zinc and 1.6% silicone, applied to the steel core in a hot-dipped process. The aluminum gives barrier protection and the zinc gives sacrificial protection. Corrosion resistance is nearly twice that of galvanized steel. A clear acrylic coat is added to prevent hand and foot marking and to add formability and corrosion protection during transit and storage.

The SMP paint system is SemCoat SP. It is applied to cleaned and pre-treated steel on a continuous coil coating line. The exposed surface gets a 2-coat system of compatible primer and color coat. The unexposed side gets an additional 2-coat system. The system gives balanced exterior gloss, color retention, chalk resistance and formability.

Silicone modified polyester painted metal carries a limited 40-year warranty. Metal substrate corrosion shown as rusting is excluded from that warranty.

Acrylic coated Galvalume is covered by a limited 25-year warranty against rupture, structural failure and perforation. Surface rusting from substrate corrosion is excluded. The mill finish is not painted, so the appearance of new and weathered material is uniform only to the degree a mill finish allows. A painted finish gives a uniform appearance.

Bare, unpainted galvanized steel is not covered by any warranty. It starts shiny and weathers, not always uniformly, to a dull gray.

The SMP finish with the 40-year paint warranty comes in 20 colors:

• Bright White
• Polar White
• Ivory
• Light Gray
• Smoke
• Armadillo
• Black
• Black Crinkle
• Light Stone
• Timber Tan
• Desert Sand
• Brown
• Burnished Slate
• Crimson Red
• Rustic Red
• Hawaiian Blue
• Gallery Blue
• Colony Green
• Pine
• Copper Penny

Flashings are available in a wide variety of colors to match the panels.

The roof deck is CDX plywood. Inside Miami-Dade, new construction takes a minimum of 19/32 inch plywood. Re-roofing takes a minimum of 15/32 inch plywood. Outside Miami-Dade, the minimum is 15/32 inch plywood.

On minimum 15/32 inch CDX plywood, the maximum tested design pressures for 26 gauge minimum are:

• Field, Zone 1: -71 psf, with fasteners at a maximum of 24 inches on center
• Perimeter and corners, Zones 2 and 3: -123.5 psf, with fasteners at a maximum of 24 inches on center

Interpolation is allowed between the field and the perimeter and corner test pressures. Outside the Miami-Dade HVHZ compliance area, extrapolation and rational analysis by a Florida licensed architect or structural engineer is allowed. Inside the HVHZ, extrapolation and rational analysis is not allowed above the maximum tested design pressures.

Dimension (a), which sets the width of the perimeter zones, is 10% of the minimum width of the building or 40% of the mean height of the roof, whichever is smaller. It cannot be less than 4% of the minimum width of the building or 3 feet.

Testing covers fire per ASTM E108 or UL790, wind driven rain per TAS 100 and structural capacity per TAS 125.

Approvals issued for SM-Rib:

• UL Class A fire resistance
• UL 2218 Hail Impact Class 4
• Florida Building Code approval, 29 gauge minimum
• Miami-Dade Notice of Acceptance, 26 gauge minimum

The specification sets quality requirements for the manufacturer. The manufacturer has at least five years of experience making panels of this type in a permanent, stationary, indoor production facility. Uplift resistance is tested to UL 580 Class 90 or higher. An independent quality assurance inspection program validates certified material and finished product specifications. Permanent ink marking on each panel identifies the manufacturer, the building code approvals and the date of production. The product is listed in the UL fire resistant directory.

Referenced standards are the SMACNA Architectural Sheet Metal Manual, the AISC Steel Construction Manual, the AISI Cold Form Steel Design Manual and ASTM A792, A527, A526 and A446. Installers have at least two years of experience on panel projects of this type.

The SM-Rib system has matching trim and flashing in a complete accessory line:

• Ridge cap RC-2 and ridge/hip cap RC-2, RC-6 and RC-8
• Drip cap DC-1
• Base drip BD-1
• Preformed valley PV-1 or PV-2
• Side wall flashing SW-1
• Eave drip ED-1 and eave flashing EF-3
• Gable rake GR-2
• End wall flashing EW-1
• Fascia cover FC-5, FC-7 and FC-9
• Inside corner IC-1
• Double angle DA-1
• Transition flashing TF-1
• Gambrel flashing GF-1
• Pipe boot

Panels arrive packaged against transportation damage. Extreme care in unloading, storing and erecting prevents bending, warping, twisting, and end and surface damage.

All material and accessories are stored above ground on well skidded platforms under waterproof covering. Ventilation between the panels prevents condensation buildup.