screen wall

A screen wall is a non-load-bearing wall built on a rooftop to conceal mechanical equipment, HVAC units, or other building systems from view, while also reducing wind load and turbulence around those installations. Unlike a structural wall that carries building weight, a screen wall is supported entirely by the roof deck and transfers only its own weight and wind pressure downward. It is typically built from horizontal girts (usually steel or pressure-treated wood members spaced 24 to 48 inches apart vertically) with a facing material attached to the framework.

The facing material varies by project requirements and location. Metal panels, typically aluminum or galvanized steel, are common because they are lightweight, durable in rooftop exposure, and require minimal maintenance. Wood boards, composite panels, or wire mesh are also used depending on aesthetic goals and budget. The gaps between girts are sometimes left open to allow air circulation, reducing wind resistance and allowing maintenance access behind the screen.

Wind and Acoustic Considerations

Screen walls reduce wind velocities that would otherwise swirl around rooftop units, decreasing vibration and noise transmission into the building. However, a solid screen wall can create excessive pressure on a roof during high winds; engineers often specify perforated or partially open designs to allow wind to pass through rather than push against the wall. The height and density of the screen directly affect its wind load; a screen wall 4 feet tall with 50 percent solid coverage presents a different pressure profile than a 8-foot solid wall.

Installation begins after the roof membrane is complete. Girts are bolted to curbs (typically steel angles or concrete blocks) that are adhered or mechanically fastened to the roof deck. This curb system distributes loads across the roof and prevents water from pooling at the wall base. All penetrations and seams must be sealed to prevent water intrusion, and the base of the screen must slope or drain properly to shed rainfall.

The term "screen wall" distinguishes this element from a full parapet (which sits at the building perimeter and is often structural) or a partition wall (which is interior). Because screen walls are non-structural and temporary in nature, they are sometimes removed or relocated when building systems are upgraded. However, they must still comply with wind load calculations for the building's geographic location and comply with local rooftop attachment codes and wind resistance standards.