Attic Vent Insulation Requirements

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

Attic vent insulation requirements.

Proper attic ventilation can be an impor tant performance consideration when design ing and installing steep slope roof systems. Fans and vents may be installed on the roof system that will draw the air out of the. Attic ventilation works on the principle that heated air naturally rises primarily utilizing two types of vents. For the same reason insulation shouldn t touch the roof s underside.

Code requirements the international building code. The majority of the requirements related to attic ventilation have not changed much from the previous editions. Unvented attic assemblies unvented attics rely on an air impermeable insulation installed to the roof deck s underside i e. Whole house fans powered attic fans.

Intake vents located at the lowest part of the roof under the eaves allow cool. Attic ceiling to stop airborne moisture from reaching a cold surface and condensing inside the building envelope in this design insulation effectively separates the interior and exterior spaces while slowing down moisture flow so the dewpoint is not achieved within. Federal housing authority recommends a minimum of at least 1 square foot of attic ventilation evenly split between intake and exhaust for every 300 square feet of attic floor space. Covering up the soffit vents with loose fill or batts which can happen if you stuff insulation along the eaves is a huge no no.

1 300 ventilation ratio recommended. The recommended ventilation ratio to provide for vented attic assemblies when an air barrier is present is the 1 300 ratio as specified by most building codes. Typically building codes include minimum requirements applicable to attic ventilation. The following are the requirements taken directly from the irc.

Let owens corning roofing help you calculate exactly how much ventilation you will need for a healthy and balanced attic with our 4 step ventilation calculator. Good roof ventilation can do this but shingle color sun exposure and insulation are exponentially more important to overall energy efficiency than ventilation. The roofing industry also has practical guide lines for attic ventilation. In addition insulation baffles must be installed at the point where the attic floor meets the roofline to prevent the attic insulation from migrating into the cavities and restricting the airflow from the soffit vents.

Roof insulation thermal resistance at roof perimeter should be equal or greater to thermal resistance of exterior wall. Enter square footage calculate or enter the square footage of the attic or area to be vented.