© SCS Global Services Page 1 of 5 Independent Assurance Statement To Owens Corning’s Stakeholders SCS Global Services (SCS) has been engaged by Owens Corning to provide independent assurance for their 2021 Sustainability Report. SCS conducted a moderate level of assurance on the report in adherence to AccountAbility’s Principles of Inclusivity, Materi ality, Responsiveness, and Impact. In addition, SCS conducted assurance on key performance indicators provided in the Owens Corning 2021 Sustainability Report. This was a remote engagement which took place from September 2021 to March 2022. Objective The objective of this assurance engagement was to provide an independent opinion on Owen s Corning’s reporting of qualitative and quantitative claims and their supporting management systems so as assure stakeholders of the overall credibility of the reported i nformation within the scope . Scope The scope of Owens Corning’s 202 1 Sustainability Report and this assurance engagement includes all of Owens Corning’s sites and activities under their operational control globally. A Type 2 assurance engagement was performed on Owens Corning’s performance against AccountAbility’s AA1000 Principles (2018) to a moderate level. Energy use, S cope 1 and 2 greenhouse gas emissions , Scope 3 greenhouse gas emission categories 1, 3, 4, 6, 7, 9 and 12, employee engagement (% responding and % actively engaged ) and types and amounts of philanthropic c ontributions have all been assured to a high level . All other data within the R eport, including but not limited to, performance data and progress towards 2030 goals were assured to a t least a moderate level. In addition, SCS evaluated the Report ’s adherence to Global Reporting Initiative’s Consolidated Set of GRI Sustainab ility Reporting Standards (202 0). Standards SCS pe rformed the assurance of Owens Corning ’s 2021 Sustainability Report against the AA1000 Assurance Standard AA1000AS v3 (2020) . Specific performance data were assessed utilizing internationally recognized standards which include, but are not limited to , the following : § § AA1000 Principles Standard (2018) § § World Resources Institute’s Greenhouse Gas Protocol: A Corporate Acco unting and Reporting Standard (R evised Edition), March 20 04 along with Scope 2 and Scope 3 Guidance § § ISO 14064- 3:2006 Specification with guidance for the validation and verification of GHG assertions . § § Consolidated Set of GRI Sustainability Reporting Standards 2020 § § Dow Jones Corporate Sustainability Assessment (CSA) 2021 2021 Owens Corning Sustainability Report | Appendices | 345 ASSURANCE STATEMENT Appendix F