Vented Insulated Roof Sheathing

There are traditionally four main reasons for venting a roof.

Vented insulated roof sheathing.

Controlling ice damming by keeping the roof cold. Consisting of acfoam ii or acfoam iii polyisocyanurate polyiso insulation board and a min. Unvented roofs vented roof. 7 16 apa teco rated osb or min.

Enhancing roofing material life span by reducing sheathing temperature. A strong resilient roof is a home s first line of defense when the roof deck is exposed to weather. Open or closed cell spray foam is applied to the underside of the roof sheathing and additional fiberglass or cellulose insulation is blown in as a cost saving method for meeting high insulation requirements and filling in the cavity space between the rafters to the ceiling deck. The ventilated roof insulation should be a factory assembled panel consisting of one layer of 7 16 11 1 mm oriented strand board top surface a built in ventilation space maintained by 1 25 4 mm wood spacer blocks and polyisocyanurate insulation on the bottom.

Staple plastic or foam baffles to the roof sheathing near the eaves to keep the material away. Hunter cool vent cool vent is a venting composite insulation board that consists of a 4 x8 panel of rigid polyiso a middle layer of solid wood spacers creating a standard 1 air space and a top layer of apa teco rated osb or plywood. 19 32 cdx plywood separated with and bonded to 5 individual 1 0 1 5 or 2 0 vent spacer strips acfoam crossvent is offered in a variety of composite thicknesses. For the same reason insulation shouldn t touch the roof s underside.

A vented attic where insulation is placed on an air sealed attic floor is one of the most underappreciated building assemblies that we have in the history of building science. So i ll start by saying something that might sound controversial but really isn t. Zip system roof assembly combines our revolutionary integrated sheathing and flashing tape or liquid flashing to provide a sealed roof for protection against moisture intrusion during construction or if high winds strip the roof covering away. Insulated roof assemblies can be vented or unvented.

Ventilated roof insulation a. So much information has been devoted to the subject of roof venting that it s easy to become confused and to lose focus. There are at least two good reasons why this approach makes more sense than installing the insulation under the roof sheathing. Removing moisture from roof cavities structural members sheathing and insulation.

The airflow from the soffits to the ridge vent keeps the roof cool and prevents ice dams and the material will block that flow.