Corrugated Metal Roofing

Corrugated metal roofing from Gibraltar Building Products is an exposed fastener roof system. The panels have a wavy corrugated profile and join at a sidelap seam. Screws pass through the panel face, which is the exposed fastener style used for metal roof replacement with exposed-fastener panels.

The panels are made by the Gibraltar Building Accessories Division. They are suitable for residential, agricultural and interior applications.

Panels are available in 2 1/2″ and 1 1/4″ sizes. The material has a long service life and is fully recyclable. A wide variety of colors, panels and accessories is offered, and technical support is available.

The recommended minimum for roof slopes is 3:12 pitch. The same panel also serves as siding, so one profile can cover both the roof and the walls of a building.

Two corrugated profiles are made. Each is named by its pitch between waves and its rib height.

• 2 1/2″ x 1/2″ corrugated: 1/2″ rib height, 2.667″ between waves. Roofing coverage is 21 1/2″ and siding coverage is 24″. Panels are 24″ wide overall.
• 1 1/4″ x 1/4″ corrugated: 1/4″ rib height, 1 1/4″ between waves. Siding coverage is 24″. The panel is 26″ overall.

The sidelap seam sets the coverage. On the 2 1/2″ panel the 24″ width overlaps its neighbor to leave 21 1/2″ exposed on a roof. On a wall the same panel covers 24″.

The panel texture is smooth. The panel style is sidelap seam with exposed fasteners. Screws drive through the crest of the wave on the roof. On siding, screws sit at the sidelap between panels.

Both profiles are made at the Jacksonville, Florida plant (SEMCO). The 2 1/2″ x 1/2″ profile is also made at a second plant.

The base metal is steel with a metallic coating. The specified substrates are:

• 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.

Three finishes are listed in the specification. Each has its own warranty position.

• Silicone Modified Polyester (SMP) paint: sold as Semcoat Superl siliconized polyester. It carries a limited 40-year warranty covering film integrity, chalk resistance and fade resistance. A 2-coat system of primer and color coat goes on the exposed surfaces, with an additional 2-coat system on the unexposed side.
• Bare AZ-50 acrylic Galvalume, mill finish: aluminum-zinc alloy coated steel with a clear acrylic coating. It carries a limited 25-year warranty against rupture, structural failure and perforation.
• Bare G-90 hot dipped Galvanized: a pure zinc layer over a steel core. Bare Galvanized steel is not covered by any warranty.

The aluminum-zinc alloy coating is 55% aluminum, 43.4% zinc and 1.6% silicone. The aluminum gives barrier protection and the zinc gives sacrificial protection. Its corrosion resistance is nearly twice that of Galvanized steel.

The clear acrylic coating prevents hand and foot marking. It also adds formability and corrosion protection during transit and storage. The finish stays a mill finish, so painted metal is the choice where a uniform appearance is expected.

Surface rusting of the metal substrate is not covered by the SMP or the acrylic Galvalume warranty. Galvanized steel is shiny when new and weathers to a dull gray, not always uniformly.

The SMP paint finish with its 40-year paint finish 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

Bare mill-finished Galvalume is unpainted and has no color range.

Panels fasten to a substrate of minimum 15/32″ CDX plywood. The roof pitch is 3:12 or greater.

The fastening schedule divides the roof into zones. Zone 1 is the field. Zones 2 and 3 are the perimeter and corners, found at the eave, the gable and the ridge. Dimension (a) sets the width of the perimeter zones. It 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 either 4% of the minimum width of the building or 3 feet.

Maximum tested design pressures are for 26 gauge minimum panels on min. 15/32″ CDX plywood:

• Field, Zone 1: maximum design pressure -86 psf, maximum fastener spacing 16″ on center.
• Perimeter and corners, Zones 2 and 3: maximum design pressure -116 psf, maximum fastener spacing 12″ on center.

Interpolation is allowed between the field and the perimeter and corner test pressure values.

Handling and storage follow set rules. Panels are delivered to the site packaged against transportation damage. They are unloaded, stored and erected with extreme care to prevent bending, warping, twisting, and end and surface damage. Material and accessories are stored above ground on well skidded platforms under waterproof covering. Ventilation between panels prevents condensation buildup.

Installers have a minimum of two years of experience in panel projects of this nature. Flashing and sheet metal work falls under Section 07600.

The panel is tested against these standards:

• ASTM B117 coating test, 1000 hours.
• ASTM G23 coating test, 2000 hours (G23/G155 listed in the fastening schedule).
• Fire testing per ASTM E108 or UL790.
• Wind driven rain test per TAS 100.
• Structural capacity test per TAS 125.

Approvals issued for the corrugated panel:

• UL Class A fire resistance.
• UL 2218 hail impact Class 4.
• Florida Building Code approval.

The sell sheet marks the product with the State of Florida approved symbol and the UL classified mark.

Eleven accessory types match the corrugated system. Each has a part code, and bend angles marked Varies depend on the roof.

1. Gable rake, EF-3. Face widths of 3 3/4″ and 2″, with a 5/8″ and 1/2″ hem.
2. Ridge/hip cap, RC-2 or RC-8. A 4 1/8″ leg and a 1 3/8″ leg, with 7/8″ and 1/2″ hems and a 135° angle.
3. Ridge cap, RC-3. A 2 7/8″ leg, a 1 3/4″ radius and 135° angles.
4. Preformed valley, PV-1 or PV-2. A 12 3/4″ leg, a 1″ rib and a 60° angle.
5. Side wall flashing, SW-1. A 3 3/8″ upstand, a 3 1/2″ base and a 135° return of 1 1/16″.
6. Eave drip/eave flashing, ED-1/EF-3. A 2 3/4″ top, a 2 1/2″ face and 5/8″ and 3/8″ returns.
7. Fascia cover, FC-5/FC-7/FC-9. A 2 1/2″ base, a variable height A and a 1/2″ open hem.
8. End wall flashing, EW-1. A 4 3/16″ upstand and a 4 1/2″ base with a 1/2″ hem.
9. Pipe boot. A stepped cone-shaped boot for pipe penetrations.
10. Gambrel flashing, GF-1. A 7 1/4″ leg and a 6″ leg with a 1/2″ hem.
11. Transition flashing, TF-1. A 7 1/4″ leg and a 6″ leg with a 1/2″ hem.

The 2 1/2″ x 1/2″ panel has a 1/2″ rib. Its roofing coverage is 21 1/2″ and it also covers 24″ as siding. It is made at two plants.

The 1 1/4″ x 1/4″ panel has a shallower rib and a tighter wave. It covers 24″ as siding. It is made at the Jacksonville plant.

SMP painted panels suit projects that need color. The 20-color range and the 40-year warranty apply. Bare Galvalume with acrylic coating suits projects that accept a mill finish and a 25-year warranty.

Residential roofs, agricultural buildings and interior walls and ceilings are the stated applications. All are recommended for a pitch of 3:12 or more.