Unvented Roof With Fiberglass

Insulating unvented roof assemblies.

Unvented roof with fiberglass.

Code pushes the envelope iecc vs irc ibc. Cellulose is a good choice for the especially environmentally conscious as it is made from. 14 inch i joists with 5 inches of closed cell foam sprayed on the underside of the roof desk. Unvented roofs have a number of advantages.

Here s what it looks like. However if moisture is able to enter the unvented attic space it may lead to roofing panel issues. Owens corning calls this proprietary insulation method the propink high performance conditioned attic system. The amount of exterior insulation needed depends on the climate zone.

Owens corning a leading manufacturer of fiberglass insulation is now promoting a package of products basically blown in fiberglass insulation and a new type of insulation netting to create unvented conditioned attics. Ventilation becomes more difficult the more complicated a roof s construction is. It is estimated that over 100 000 have been constructed since 1995. If you want to put air permeable insulation like fiberglass or cellulose against the roof deck between the rafters rigid insulation board must be placed on the exterior of the roof deck according to the provided r value ratio tables.

However when roof. Unvented attic assemblies spaces between the ceiling joists of the top story and the roof rafters and unvented enclosed rafter assemblies spaces between ceilings that are applied directly to the underside of roof framing members rafters and the structural roof sheathing at the top of the roof framing members rafters shall be permitted if all the following conditions are met. Unvented roof assemblies such as conditioned attics and unvented cathedral ceilings are becoming common in north american construction. Mapping out the roof assembly for a new house in climate zone 6b steve mackay has settled on long i joists insulated with a mix of closed cell spray polyurethane foam and blown in fiberglass.

These assemblies are created by eliminating ventilation openings and moving the thermal moisture and air control boundaries to the plane of. Wood roofing panels endorsed by the apa usually contain an in service water content of between 4 and 16. Gutex thermofiber a blow in wood fiber insulation is a very ecological choice which is ideal. As a result unvented roofs have become popular in homes with feature dense roofs think multiple skylights dormers and other aesthetic flourishes.

In this post we will show that while the propink unvented insulation system may provide a safe roof in zones 2b 3b if we instead combine dense fiberglass insulation batts or densepacked with intello smart vapor retarder and airtight membrane we can make safe and robust unvented roofs in climate zone 6.