Metal Roofing is a Common System for Low-Slope and Flat Roofing Systems Such as Those Used in Industrial and Storage Facilities. Despite its Longevity, a Metal Roof Will Require a Retrofitting When It Displays a Functional Deficiency or Reaches to the End of its Service Life. One of the Common Retrofitting Methods is to Use a Thermoplastic Polyolefin Single Ply Membrane Due to its Ease of Installation, Economic Efficiency, and Lightweight. a Single Ply Membrane Typically Relies on the Existing Metal Deck System as a Structural Deck and Provides Insulation and Protection Against Wind Uplift. This Paper Presents a High-Fidelity Finite Element Model to Investigate the Behavior of a Single Ply Membrane Retrofitting Metal Deck Roof under Wind Uplift. the Developed Finite Element Models (FEMs) Were Validated with Experimental Results of Three Full-Scale Retrofitted Metal Deck Systems using Thermoplastic Polyolefin (TPO) Membrane. Parametric Study Was Carried Out to Investigate the Effect of Different Fastener Patterns, Transverse and Longitudinal Fastener Spacing, and Membrane Strength.