Unvented Flat Roof Insulation

Unvented flat roof assembly.

Unvented flat roof insulation. There are traditionally four main reasons for venting a roof. Removing moisture from roof cavities structural members sheathing and insulation. Enhancing roofing material life span by reducing sheathing temperature. Air permeable insulation such as fiberglass batts dense packed cellulose or blown in fiberglass can t be used alone for an unvented assembly since these types of insulation can allow moist indoor air to reach the cold roof sheathing leading to condensation or moisture accumulation.

Unvented roofs vented roof. Unvented roof systems where the insulation and air barrier are applied directly to the underside of the roof deck are common in applications where designers are seeking cost effective and energy efficient roof assemblies. An unvented assembly can perform well but it s important to get the details right to avoid sheathing rot. Drying of unvented roofing assemblies is by definition only provided to the interior.

Condensing surface temperature controlled the thickness of the rigid insulation at both the roof deck and perimeter is determined by a calculation procedure similar to figure 5. The colder the climate the thicker the rigid insulation required. Test roofing membranes for integrity prior to covering from below. However designers of compact roof assemblies must consider vapor permeance and arrangement of the roofing materials to produce acceptable hygrothermal performance and low.

The higher the interior moisture level the thicker the. However in many situations the insulation may need to be primarily or entirely below the flat roof membrane and between the roof joists if so what are the best options.