Unvented Flat Roof Insulation

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.

Unvented flat roof insulation.

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. 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. Unvented roofs vented roof. Controlling ice damming by keeping the roof cold.

Enhancing roofing material life span by reducing sheathing temperature. Yes unvented roof assemblies can be insulated with fiberglass a wufi post and not just in climate zones 2b amp. Senior engineer manager at icynene john broniek makes the case for the unvented attic assembly and why insulating the underside of the roof makes sense. Unvented flat roof assembly.

The colder the climate the thicker the rigid insulation required. In this case you can learn a lot from foam tech s article vented vs. Basically the term cold roof refers to a traditional roof or vented roof while hot roof refers to a roof that is not ventilated and which has foam insulation attached directly to the roof sheathing. Unvented roof assemblies such as conditioned attics and unvented cathedral ceilings are becoming common in north american construction.

An unvented assembly can perform well but it s important to get the details right to avoid sheathing rot. Unvented flat roofs a technical discussion flat roofs have often been built with the insulation all on top of the vapor closed drainage plane as this avoids dew point condensation issues inboard of the roofing. These assemblies are created by eliminating ventilation openings and moving the thermal moisture and air control boundaries to the plane of the roof deck. There are traditionally four main reasons for venting a roof.

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. Martin s post focuses on the marketing of owens corning 039 s propink unvented attic insulation system. However designers of compact roof assemblies must consider vapor permeance and arrangement of the roofing materials to produce acceptable hygrothermal performance and low. Removing moisture from roof cavities structural members sheathing and insulation.