b'UNLOCKING THE SECRETS OF STEEL ROOFING LONGEVITYTips for a durable investmentBY::SARAH MAJLESI, SENIOR ENGINEER, CFS, CISC-ICCASteel roofing options are becoming more and more popular in various construction sectors, especially the residential market, and one of the first characteristics that come to mind when describing steel roofing as a building material, as opposed to other building materials, is longevity. Several factors contribute to this important character of steel roofing which we will discuss in the form of a three-part series, with each property reviewed and elaborated on in each publication.Durability under extreme weather conditions: This will be elaboratedA big part of engineering roofing systems is working out the load further in part two of this article. There are various testing and insurancedistributionamongsttheinterconnectingcomponents.Thermal companies which provide structural requirements and demands fordeflectionisalsoofconcern,andonecouldexpectaone-mm withstanding catastrophic weather impacts.expansion per metre length of sheet steel. Thermal load contraction and expansion review is outside the scope of this article; however, it is Coating/galvanization: Information on various coating designationsessential to know that the designer must be aware of the fact that there will be covered in part three of this article. are thermal displacement structural calculations based on temperature changes available, and point of cladding to subgirt attachments must Engineered system: This may not seem obvious at first, but cold- account for the displacements. This may be assumed at eave or ridge formed steel roof cladding systems are made of tough and high- level, however, the sliding snow stiffener location may have an impact performingbuildingcomponentsthatwithstandenvironmentalon where this is located.andhumandemandsoverthecourseofthespecifieddesignWind uplift, as well as sliding snow and normal-direction projected lifespan. The calculation of gravitational as well as lateral loads fromsnow load, create the most significant impacts to the steel roofing. applicable building codes, load patterns and how they distributeDeflection criteria are normally set as L/360 and L/240, with L being within the system and supporting structure are just some examplesthesteelroofcladdingspan.Roofcladdingwithstandswinduplift of what the specialized cold-formed steel engineer considers whenthrough the seam clips, which in turn is transferred to the structure via designing the roof structure. This, in essence, is different from thesubstructure (steel subgirts), roof deck and associated attachments. specifications; i.e., water penetration, energy modelling and otherSeamclipsareeitherpenetratedornon-penetrated,depending building envelope requirements.on the architectural requirements. Snow load is projected into two ADVANTAGE STEEL WINTER 2023/2024|37'