Unvented Porch Roof With Finished Ceiling

An under roof cathedral ceiling or attic ventilation system to help the building in any way needs to be properly designed and installed with adequate intake venting at the eaves outlet venting at the ridge and with careful sealing of air leaks from the occupied space into the attic or roof cavity to avoid heat losses or increases in both moisture movement into the roof cavity and.

Unvented porch roof with finished ceiling.

Controlling ice damming by keeping the roof cold. In terms of energy savings there isn t much benefit to insulating an unheated porch. 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. Unvented roof assemblies such as conditioned attics and unvented cathedral ceilings are becoming common in north american 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 assemblies work particularly well on complex roofs that would be difficult or impossible to vent properly or on roofs where it would be difficult to insulate properly if the roof were vented. There are traditionally four main reasons for venting a roof. I installed collar ties to leave an open space above the finished room along with r 15 insullation and installed a fan on a thermostat at the end of the roof in addition to ridge vent to suck all the hot air that collected between the roof and porch ceiling.

That can be made cheaper still if using reclaimed roofing foam at a fraction of the price of virgin stock foam. However doing so will prevent cold air from seeping into the porch and may allow you to use the porch for a few weeks longer before winter arrives. Where the attic space is finished with drywall or other ceiling materials installed against the underside of the roof rafters while we prefer in floor insulation here we ll have to insulate the roof cavity between the rafters. Removing moisture from roof cavities structural members sheathing and insulation.

Basically you should be thinking about insulating the roof floor and walls to ensure the maximum benefit. Last year i replaced a flat porch roof with a 6 12 pitch. Through provision r806 4 the irc also allows you to build an unvented roof assembly. Enhancing roofing material life span by reducing sheathing temperature.

Create an unvented roof. Unvented roofs vented roof. With simple roof lines it s cheaper to do an unvented roof with exterior side roofing polyiso and all fiber in the rafter cavities. 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.