PAC T-250

PAC T-250 is a PAC-CLAD standing seam roof system from Petersen. It is an architectural and structural panel that is field seamed and has a separate seam cover. The seam cover is mechanically seamed in the field. It is listed for commercial roofing, and the listed minimum slope is 1/2:12.

Installation is bidirectional, so work can progress outward from a starting panel in either direction. Panels are produced in the factory or in the field on manufacturer-owned roll-forming equipment, and field-forming panels are available for long length requirements.

Nominal width is 16 inches or 18 inches on center. Nominal finished seam height above the deck is 2-5/8 inches. Panel conditions are smooth, listed as standard on the spec sheet, and striated, which is the factory standard when nothing else is indicated. Pencil ribs are offered only at the Illinois facility.

Maximum factory-produced panel length is 54 feet. The panel can be tapered and radiused. Seam covers are factory produced with two beads of sealant.

Four base materials are listed: .032 aluminum, .040 aluminum, 24 gauge steel and 22 gauge steel, with Galvalume Plus available. Steel meets ASTM A792/A792M (55 percent aluminum-zinc alloy coated) and aluminum meets ASTM B209. Not all materials are available at every location.

• ASTM E283 and E331, and E1680 and E1646, air and water penetration.
• ASTM E1592, structural performance.
• ASTM E2140, water penetration.
• FM 4474.
• UL 580 and UL 1897.

The system is written to UL Class 90 wind uplift under UL 580, to ASTM E1592 testing and to a UL 2218 impact resistance rating. Water penetration is limited to none uncontrolled through the panel joints under E283/1680 and E331/1646.

Continuous or intermittent clips are used. The panel attaches with concealed fastener clips inside the laps, spaced to carry positive and negative design loads while allowing the roof to expand and contract. Forming is by continuous end rolling with no end laps.

A 35-year non-prorated finish warranty and a weathertightness warranty are available. The written finish warranty is 30 years from substantial completion, covering fading beyond 5 Hunter units under ASTM D2244, chalking beyond a No. 8 rating under ASTM D4214, and plus cracking, checking and peeling of the finish. The weathertightness warranty period is 20 years, and a two-year applicator warranty applies on repairs to keep the roof and flashings watertight.

A 40 mil peel and stick membrane is specified, lapped 12 inches over hips and ridges and 6 inches over the metal of valleys and built-in gutters, as required for the 20 year weathertightness warranty. Manufacturer and erector each show a minimum of five years of experience on this type of project. The guide specification is dated August 2024 and names Petersen facilities in Illinois, Maryland, Georgia and Arizona.

The seam is symmetrical and forms the shape of a T. A metal seam cover caps the T, and a mechanical seamer bends each side under the top of the T. Seam covers are roll-formed in the factory with factory-applied sealant beads. The seam cover is limited to 30 ft and is field-lapped.

Panels can be factory-formed or field-formed to length, and all panels are field-seamed. Panels can be tapered and radiused.

Two clip systems exist. An intermittent clip is used for general fastening, and a continuous clip system is used for high-strength open-framing applications. Both accommodate thermal expansion and contraction.

Substrates are 5/8 in minimum plywood, or nailboard insulation or equivalent, with ice and water shield applied horizontally from eave to ridge. Metal decking, purlins or rigid insulation are used with bearing plates, and open framing is also covered. In coastal applications, aluminum panels with stainless steel clips are required for warranty coverage.

Test reports and evaluations cover several metals and clip types.

• ASTM 1680 and 1646: 24 gauge by 16 in
• ASTM 283 and 331: 24 gauge by 16 in
• ASTM E1592: .032 by 16, .040 aluminum by 16, 22 gauge by 16 and 24 gauge by 16, with summaries for continuous and intermittent clips
• ASTM E2140
• FM 4474: .032 by 16, .040 by 16, 22 gauge by 16 and 24 gauge by 16
• TDI product evaluations: .032 aluminum and 24 gauge steel
• Florida approval: roofing, non-HVHZ
• Sealed load span charts

The finish is a Kynar-based 70% PVDF coating. Trim and flashing are PAC-CLAD aluminum or steel, fabricated by Petersen or a qualified fabricator. Vinyl film is used where extra handling is expected, and the strippable film is removed immediately after installation.

Detail drawings in CAD and PDF cover curbs, eaves, gables, gutters, headwalls, hip and ridge, peaks, pipe penetrations, rakewalls, slope changes and valleys for metal deck, open framing and wood substrates.

• Related products: H-Shield, H-Shield CG, H-Shield HD, H-Shield HD Composite CG, H-Shield NB