Roof Venting Vaulted Ceiling

Sketch above showing venting in a steep slope cathedral ceiling roof is courtesy of carson dunlop associates.

Roof venting vaulted ceiling.

Cathedral ceiling ventilation insulation if properly installed between the rafters on top of the ceiling material drywall plaster paneling sheets etc there should be approximately 2 of space left above it which allows air to flow between the bottom and top of the roof. Now here is the contradictory part. In buildings where there is no roof venting anyway and where ventilation is difficult or impossible to achieve an un vented well insulated hot roof can provide a high r value ceiling and may be the second best alternative to preventing ice dam related leaks in cold climates. The only way to do that are gable vents for intake and ridge for exhaust.

The question and answer article below paraphrases quotes from updates and comments an original article from solar age magazine and written by steven bliss. Cathedral ceilings built using 2 x 12 roof rafters allow enough space for the fiberglass batt insulation and a 1 5 gap for ventilation. The flow of water vapor. This type of roof assembly is designed so the air can flow up the soffit vent through an insulation baffle pass through the 1 5 gap between the insulation and roof sheathing then exit through a ridge vent.

The bottom of each rafter cavity ends at the soffit which is the horizontal plane that lies just beneath. A vaulted roof features angled rafters that rest on wall plates and connect at the top to a ridge. Vented cathedral ceiling assemblies incorporate soffit or eave vents adequate open air space between insulation and roof deck sheathing and ridge vents. Foam filled cathedral ceilings may make sense in some cases.

In the case of a cathedral vault where the interior ceiling is parallel to the exterior roof line installing skylights is a simple process. Only the air space that exist at the peak if any needs venting. Ventilating cathedral ceilings step 1. These assemblies pose unique ventilation problems.

How to vent a vaulted roof vaulted roof elements. 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. Click to enlarge any image. Properly insulated cathedral ceiling assemblies incorporating air and vapor retarders can function without ventilation.

Sealing bypasses the first line of defense. To understand the necessity of proper ventilation it helps to have a basic.