Sem-Lok Metal Roofing

Sem-Lok Metal Roofing is a concealed fastener roof system from the Building Accessories Division of Gibraltar Building Products. It is a preformed standing seam metal roofing panel with a narrow rib, a vertical leg and a concealed fastener flange. Adjacent panels join with a positive snap lock seam. The seam uses male and female rib configurations.

The panel is an architectural standing seam roof system. The minimum roof slope is 3:12. The system is fire resistant. Applications are residential, architectural, commercial and industrial.

Panels cut with standard snips. The system comes in painted and bare finishes, with matching accessory trims for eaves, ridges, hips, valleys, walls, gables and fascia.

Sem-Lok is made in three profiles:

• Flat
• Ribbed
• Striated

All three profiles use the same concealed fastener flange and snap lock seam. Each profile has a side lap detail built from the panel, a CL-3 cleat, underlayment and a pancake screw.

Two steel gauges are made at the Jacksonville, Florida plant, and each gauge is tied to a paint finish:

• 24 gauge with a PVDF paint finish
• 26 gauge with an SMP paint finish

The 24 gauge panel is UL 580 Class 90 rated and Miami Dade County product approved. The 26 gauge option is also UL 580 Class 90 rated. The panel is formed in a permanent, stationary, indoor production facility on industrial equipment. Permanent ink marking on each panel identifies the manufacturer, the building code approvals and the date of production.

Three finishes are offered:

• Silicone Modified Polyester (SMP) paint, with a 40-year warranty
• 70% Fluoropolymer (PVDF) paint, with a 45-year warranty
• Bare mill-finished Galvalume with a clear acrylic coating, with a 25-year warranty

Galvalume is aluminum-zinc alloy coated steel. The alloy coating is 55% aluminum, 43.4% zinc and 1.6% silicone. The aluminum gives barrier protection and the zinc gives sacrificial protection. The clear acrylic coating prevents hand and foot marking. It also adds formability and corrosion protection during transit and storage. The 25-year warranty covers rupture, structural failure and perforation. Surface rusting from substrate corrosion is not covered.

SMP paint is applied on a continuous coil coating line to cleaned and pre-treated steel. The exposed surfaces get a two-coat system of primer and color coat. The unexposed side gets an additional two-coat system. The 40-year warranty covers film integrity, chalk resistance and fade resistance. The paint finish warranty also covers cracking, checking, blistering, peeling, flaking, chipping, chalking and fading.

PVDF paint is a 70% Fluoropolymer resin system. Kynar 500 and Hylar 5000 are trademarked examples of these resins. The resin resists color fading, acid rain, ultraviolet rays, chipping and peeling.

A Copper XT option is copper clad stainless steel, metallurgically bonded to both surfaces of Type 430 stainless steel. It carries a 50-year material replacement guarantee.

SMP panels come 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 and Copper Penny.

PVDF panels come in 20 colors: Regal White, Snow White, Almond, Sandstone, Brownstone, Surrey Beige, Medium Bronze, Aged Bronze, Mansard Brown, Ash Gray, Slate Gray, Charcoal Gray, Dark Bronze, Matte Black, Regal Red, Colonial Red, Evergreen, Regal Blue, Pre-Weathered Galvalume and Copper Penny.

Bare mill-finished Galvalume has no paint color.

Sem-Lok fastens to plywood decking through a concealed flange. The layers from the deck up are CDX plywood, underlayment, the CL-3 cleat and the panel. A pancake screw holds the cleat and the panel flange. The side lap seam then covers the fastener.

Minimum plywood thickness depends on the job:

• 19/32 inch CDX plywood inside Miami-Dade for new construction
• 15/32 inch CDX plywood for re-roofing
• 15/32 inch CDX plywood outside Miami-Dade

The recommended fastening schedule gives maximum tested design pressures for 26 gauge minimum panel on 15/32 inch CDX plywood. The field, Zone 1, is tested to -52.5 psf. Perimeter and corners, Zones 2 and 3, are tested to -120 psf with the CL-3 cleat. Maximum fastener spacing is 7 inches on center in both areas. Interpolation is allowed between the field and the perimeter and corner test pressure values.

Roof zones are set by dimension a. Dimension a 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.

Panels are packaged for protection against transport damage. Unloading, storing and erecting call for care to prevent bending, warping, twisting, end damage 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 on panel projects of this nature.

The Sem-Lok system has matching trims in the same profile family:

• Cleats CL-1 and CL-2
• High side eave HS-1
• Counter flashing CF-1
• Reglet flashing RF-1
• Z closure strip ZC-1
• Eave drip and eave flashing ED-2, ED-2R and EF-5
• Ridge and hip cap RC-10
• End wall flashing EW-3
• Gambrel flashing GF-2
• Preformed valley PV-3
• Pipe boot
• HVHZ cleat CL-3
• Vented ridge RC-20
• Transition flashing TF-2
• Side wall flashing SW-3
• Gable rake GR-9
• Fascia cover FC-5, FC-7 and FC-9

The HVHZ cleat CL-3 is the cleat used at the side lap and in the perimeter and corner zones of the fastening schedule.

Sem-Lok panels carry a UL Class A fire resistance rating and a UL 2218 Hail Impact Class 4 rating. The system holds a Florida Building Code approval. The panel is listed in the UL fire resistant directory. Fire testing is per ASTM E108 or UL790.

Wind driven rain is tested per TAS 100. Structural capacity is tested per TAS 125. Uplift resistance is tested to UL 580 Class 90 or higher.

Steel sheet standards named for the panel material are ASTM A792 for aluminum-zinc alloy coated steel and ASTM A527, A526 and A446 for zinc coated steel. ASTM B370 covers the Copper XT sheet. Design references are the SMACNA Architectural Sheet Metal Manual, the AISC Steel Construction Manual and the AISI Cold Form Steel Design Manual.