Vaulted Roof Ventilation

Depending on your house interior and roof framing design cathedral ceiling ventilation can be treated as an independent or attic ventilation related condition.

Vaulted roof ventilation.

When renovating an older home whose roof rafters are only 2x6 really 5 1 2 x 1 5 in dimension the available space for insulation and ventilation is limited therefore limiting the options for a combination of good under roof ventilation and high insulation r values in the cathedral ceiling. A ridge vent features an open strip along the length of the ridge where the air that enters the soffit can escape. Proper ventilation even with the attic bypasses sealed and effective vapor retarders installed proper ventilation is essential to prevent moisture problems in cathedral ceilings. That is create a vent channel above the insulation with low and high vents.

Is the radiant barrier in a useful place. If the attic space is going to be conditioned either for living or mechanical purposes or if a home design calls for a vaulted ceiling provision r806 3 in the international residential code calls for the roof deck above the space to be vented continuously from the eave to the ridge. Without an attic baffle there will not be any air space for fresh air to enter the attic from the soffit vents. Cathedral vaulted or any ceiling that has insulation blocking the airflow from the soffit vents to the attic needs an attic baffle in each rafter bay.

In my proposed cathedral ceiling detail sketch at left i want to use a reflective foil between the insulation and the roof sheathing to double as a radiant barrier and a cathedral ceiling ventilation space liner. Then insulate below with fiberglass or cellulose add a vapor retarder and your finish ceiling. James french suffern ny. You ll want a tight ceiling air barrier with no air leakage into the cathedral ceiling a critical detail for all cathedral ceiling designs.

Proper attic ventilation consists of a balance between air intake at your eaves soffits or fascias and air exhaust at or near your roof ridge. Vent the roof deck. 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. In a vaulted roof a ridge vent serves as the outtake or exhaust vent.