Roof Ventilation For Vaulted Ceilings

These assemblies pose unique ventilation problems.

Roof ventilation for vaulted ceilings.

Properly insulated cathedral ceiling assemblies incorporating air and vapor retarders can. Attic ventilation for cathedral and vaulted ceilings require attic baffle vents with v baffe s design you can quickly and easily retrofit cathedral and vaulted ceilings that would otherwise have been next to impossible. Ventilation of vaulted ceilings vaulted ceilings sometimes referred to as cathedral ceilings occur in steep slope roof assemblies in which there is no attic space between a ceiling and roof deck. Vaulted ceilings can be constructed by either stick framing which means attaching each joist and rafter individually or by setting roof trusses that come engineered from a truss manufacturer.

Because the roof isn t in play here it doesn t matter how many hips valleys dormers or gables there are. In mixed climates ventilation serves either role depending on the season. 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. Chimneys recessed lights plumbing chases and holes drilled through top plates for plumbing or wiring should all be sealed figure 2 53 at left.

As for how much insulation to use the minimum would be a 2 inch board which will get you about r 12 plus a little extra from the foil facing. A key benefit of venting the attic is that the approach is the same regardless of how creative your architect got with the roof. Proper ventilation even with the attic bypasses sealed and effective vapor retarders installed proper ventilation is essential to prevent moisture problems in cathedral ceilings. A balanced system of soffit and ridge ventilation provides continuous ventilation of hot moist air at the hottest point of the roof.

The air space above the insulation will provide some relief in the event of a roof leak even without ventilation. Penetrations roof ventilation challenges common air leak points in ceilings pay special attention to penetrations in the ceiling plane particularly in cathedral ceilings. In a vaulted roof a ridge vent serves as the outtake or exhaust vent. Depending on your house interior and roof framing design cathedral ceiling ventilation can be treated as an independent or attic ventilation related condition.