Insulate Unvented Roof

You need enough exterior foam to prevent condensation on the inside of the roof sheathing by keeping that plywood warm.

Insulate unvented roof.

Unvented roof assemblies should be insulated either with air impermeable insulation rigid foam or spray polyurethane foam or with a combination of foam and air permeable insulation. When hvac equipment is in the attic insulation and. However architects of these compact roof assemblies must consider vapor permeance and arrangement of the materials to produce acceptable hygrothermal performance and low risk of condensation in the resulting conditioned attic space. Insulating the underside of roofs making the case for the unvented attic assembly background.

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. Four options for building an unvented roof assembly. To provide an unvented conditioned space for locating hvac equipment in the attic and or to provide a continuous thermal barrier for designs that have complex coffered ceiling planes and or numerous penetrations for lights speakers vents soffits etc which make it difficult to achieve an airtight ceiling plane. Low slope and steep slope unvented roof systems i e.

Install insulation along the underside of the roof deck of an unvented attic rather than on the ceiling deck of a vented attic for either of two reasons. Don t stay stuck in the sci fi nightmare of foam foam foam. Advantages of unvented attic assemblies. Exterior insulation solves a lot of thermal nosebleeds but the amount of foam you put on the outside needs to be proportional with the amount of insulation on the inside within the rafter cavity.

An unvented attic differs from a conventional vented attic in that there is no direct venting of the attic. We re big fans of fine homebuilding. Insulating unvented roof assemblies.