This portable steel in plant office, also known as modular inplant office or prefab office has an overall footprint of 8' x 12' and includes a main office area with windows for a supervisor as well as a utility room for storage of equipment and tools necessary to the operation in this particular area of the manufacturing plant. Each room includes a hinged steel door with louvers for ventilation. The blank walls on the back side of the in plant office provide room for the thru wall HVAC unit and for customer mounting of equipment, panels, etc. The welded frame is made of tubular steel construction with double panel steel wall construction for superior durability. All included electrical is prewired to a wall mounted circuit breaker box with main.