The new 115,260-square-foot Mountainside Middle School houses 17 mainstream classrooms; two 'options' classrooms; six science classrooms; an art room; band and choral suites; three resource rooms with separate DLC suite and support spaces; a library/media center; two separate gymnasiums with adjacent locker facilities, fitness room, weight room, and wrestling/climbing room; industrial technology shop and classroom; and various educational and building support facilities.
Natural buffers of trees and vegetation line the entire east and west sides of the site. The building sets back approximately 350 feet from the road, which allows for landscaping and visual relief from vehicle traffic. Outside site improvements include an eight-lane track with a football/soccer field contained within, two baseball fields, two softball diamonds, shot-put area, and a full-size soccer/P.E. field. The site includes a dedicated bus loading lane with a separate area for DLC buses, a separate lane for student drop off/pick-up, and parking for 300 cars to accommodate event parking.