Unvented Sip Roof

This style of roof helps to prevent moisture buildup.

Unvented sip roof.

3 8 plywood diaphragm seams taped. Need to make a final decision on which underlayment to use under a metal roof on an unvented roof system. This document provides a brief description of different types of unvented roof assemblies and the benefits of unvented roof construction. These assemblies are created by eliminating ventilation openings and moving the thermal moisture and air control boundaries to the plane of the roof deck.

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. In order for an un vented roof assembly to function properly the following conditions must be in place. Unvented roof assemblies such as conditioned attics and unvented cathedral ceilings are becoming common in north american construction. With tribuilt granulated self adhering underlayment on top of the plywood.

With an unvented sip roof the argument would be that the exterior osb facing constitutes the structural sheathing referred to in the code. Sip roofs have extreme advantages over traditional framed roofs. Therefore an unvented sip roof is permitted under irc r806 5 unvented attic and unvented enclosed rafter assemblies. When constructing unvented roofs with asphalt shingles in hot humid climates a vapor barrier must be installed between the asphalt shingles and the roof deck.

Extreme insulation up to r 51. Beams on 5 centers. Integrated sheathing and roof deck for a one stop roof framing product. Venting at the ridge and eave allows air to move freely between the two layers of sheathing.

Factory engineered and precut per floor plans all but eliminating measuring or cutting material for roof structures. The roof is currently built as follows. Next i ll be screwing down 5 1 2 raycore sips panels over heated space and framing boxes over the eaves covering everything with 5 8 cdx. 1 1 2 t g decking.

Create a cold roof by applying a layer of sheathing over 1 3 furring 16 in. According to the builder s guide to structural insulated panels sips published by building science corporation the typical reduction of shingle life over an unvented sip roof assembly is between one and two years. Un vented roofs operate on the principle that moisture entering the roof assembly can be controlled and that there is no need for venting to control moisture accumulation. Four options for building an unvented roof assembly.

Asphalt shingles store water from dew condensation due to night sky cooling and rain. This receptor is an air space that can be accomplished in a variety of ways.