"zinc"

Four Key Components Constitute Prefinished Sheet Steel Prefinished sheet steel for construction consists of four major components: the sheet steel itself, a metallic (zinc or aluminum-zinc alloy) coating, chemical pre-treatment and primer, and a top coat. Each performs an important role in providing designers with a high quality, aesthetic, cost competitive and corrosion-resistant material. The backbone of the system is sheet steel, an ideal material for covering large surface areas because of its economy and high strength-toweight ratio. Protection against the demanding Canadian environment is provided by the metallic coating, one of the most effective methods of protecting bare steel from corrosion. Both zinc and aluminum-zinc alloy provide a tough, non-porous coating

Introduction Most cold formed steel building products, whether painted or unpainted, are manufactured from a sheet steel material that has some form of metallic coating applied. This metallic coating can be zinc (galvanized), zinc-iron alloy (galvanneal) or a 55% aluminum-zinc alloy (GalvalumeTM). The metallic coating is available in a range of thicknesses to provide the degree of corrosion protection and service life required. One of the concerns expressed by installers relates to the presence of wet storage staining on the products, how this staining impacts the long term performance, and what can be done to remove it. The purpose of this fact sheet is to address some of these issues, allay some fears, and give guidance on proper storage techniques.

CSSBI Position Paper on CGSB Standards for Prefinished Sheet Steel Cladding The National Building Code of Canada 2010 includes references to two documents published by the Canadian General Standards Board (CGSB) dealing with prefinished sheet steel cladding. These documents are: • CAN/CGSB-93.3–M91 Prefinished Galvanized and Aluminum-Zinc Alloy Steel Sheet for Residential Use • CAN/CGSB-93.4–92 Galvanized Steel and Aluminum-Zinc Alloy Coated Steel Siding, Soffits and Fascia, Prefinished, Residential It is important to realize that there are no sheet steel products currently manufactured in Canada that meet the requirements contained in these CGSB standards. 

1. SCOPE 1.1 The following specifications shall apply to hot-dipped metallic-coated sheet steel prefinished with colours of proven durability and suitable for exterior exposure as delivered from the coil coater. Proven paint systems for building products have been designed for vertical applications whose surfaces are no more than 30° to the vertical and non-vertical applications whose surfaces ranging from 5° up to 60° to the horizontal. It is not recommended for aggressive atmospheric exposure. 1.2 The prefinish system shall consist of a primer and topcoat continuously applied and cured within the paint manufacturer’s specifications on cleaned, pretreated, metallic-coated substrate. The pretreatment specified shall be zinc phosphate for galvanized steel and metal oxide pretreatment for aluminum-zinc alloy-coated steel, applied in accordance with the pretreatment manufacturer’s specifications.

Architects and Specification Writers are increasingly selecting unpainted metallic coated steels for architectural roofing and cladding applications on building exteriors where they want a “Silver” metallic finish. This is occurring more frequently, and even on “prestige” type projects. The Canadian Sheet Steel Building Institute whose fabricator members manufacture a wide variety of building panel profiles for roofing and cladding applications, are being asked to supply unpainted (natural finish) galvanized or resin coated 55% Aluminum-Zinc coated steel for these architecturally exposed end uses. Oftentimes, these materials are specified because the designer finds the natural finish of these products very appealing and sometimes because of material cost savings opportunities. This Fact Sheet has been developed to provide guidance in material selection and provide information on the Architectural Metallic Finishes that are available for highly visible steep slope roofing and cladding applications. 

IntroductionSheet Steel Roong and SidingLightweight Steel FramingIsolate the Steel and Wood ComponentsAvoid Use of Pressure Treated WoodFastenersMany buildings will include wood members in applicationssuch as sill plates, splash boards, strapping, purlins, door orwindow bucks, and posts. In some of these end-uses it is arequirement that the wood be chemically treated (pressuretreated) to extend the service life.Designers and builders need to be aware that changes in theavailable wood perservatives may impact the durability ofany connected steel components or fasteners.Eective January 1, 2004 the Environmental ProtectionAgency (EPA) banned the use of Chromated CopperArsenate (CCA) as a preservative in treated lumber forresidential construction. This was done in an eort to reducethe use of chromate and arsenic thereby mitigating thepotential health and environmental problems. The woodpreservative industry has been switching to alternativewaterborne compounds including Sodium Borate (SBX),Alkaline Copper Quat (ACQ), Copper Azole (CBA-A and CA-B),and Ammoniacal Copper Zinc Arsenate (ACZA).Unfortunately, research has indicated that ACQ, CBA-A, CA-Band ACZA, the new generation copper-based products, aremore corrosive to galvanized steel than the former CCA.Since ACQ is becoming the predominant preservative in use,the discussions in this paper will refer to it exclusively.The purpose of this Fact Sheet is to convey the recommendations of the sheet steel industry for the application of steelproducts with ACQ pressure treated wood.