Table of Contents
What is the best insulation for cathedral ceilings?
Note: Most experts agree that closed-cell foam is best for unvented cathedral ceilings while vented cathedral ceilings can be insulated with less expensive open-cell foam.
Do cathedral ceilings need insulation?
If your cathedral ceiling is built this way, it will have truss joists, scissor truss framing, or sufficiently large rafters. The best way to insulate this type of cathedral design is with batted insulation. For example, cathedral ceilings built with 2×12 rafters have space for standard 10-inch batts and ventilation.
What R-value do I need for cathedral ceilings?
R-value minimums. In Climate Zones 4, 5, 6, 7, and 8, most prescriptive building codes require ceiling insulation to have a minimum R-value of R-49. In Zones 2 and 3, the minimum requirement is R-38, while in Zone 1, it’s R-30.
Should you vent a cathedral ceiling?
Ice dams may cause water to flow laterally underneath a steep-slope roof covering and eventually enter a building’s interior. For these reasons, cathedral ceilings should be ventilated. Ventilation is the movement of air to reduce heat and/or moisture accumulation between buildings’ interiors and exteriors.
How do you stop condensation on a cathedral ceiling?
An airtight air barrier is the key to success with cathedral ceilings with fibrous insulation. Roof ventilation is an important backup, but will not prevent moisture problems with a leaky ceiling.
How do you insulate a sloped ceiling?
Insulating Unvented Sloped Ceilings
- Install 7 inches of spray foam on the underside of the roof sheathing and leave the rest of the rafter cavity open.
- Install 4 inches of spray foam on the underside of the roof sheathing and fill the rest of the cavity with fiberglass batts.
How thick should rafter insulation be?
100mm to 200mm
Common rafter depths range from 100mm to 200mm. This limits the maximum thickness of the insulation between the rafters to between 50mm and 175mm. This generally would not be a sufficient thickness to achieve the U-values required to meet Building Regulations and more insulation would need to be added.
How do you insulate cathedral ceilings without ridge vents?
In cases where there is no under-roof venting system (no soffit intake vents, no ridge vents), a “hot roof” design is followed: the roof cavity between rafters can be filled with insulation, followed by installation of a perfect vapor barrier, followed by finish surface of drywall or whatever else.
Why is my vaulted ceiling sweating?
The upper walls and roof are sun-exposed, so there would have been air-heating and expansion. With only one penetration in the cathedral ceiling, that warm moist air intruded into the room, encountering cool drywall ceiling and metal fan housing, resulting in condensation.
How do you stop condensation in a cathedral ceiling?
How do you vent hot air from a cathedral ceiling?
Place doorway fans in the upper corners of doorways to help circulate air throughout the home. With the fan placed to exhaust air from the room with the vaulted ceiling down the home’s hallways, this also helps to keep warm air circulating throughout the home in the winter.
How do I stop moisture in my vaulted ceiling?
To control the flow of water vapor and the potential of moisture problems in the attic, it is advised to seal all attic bypasses that may allow air leakage. Additionally, any water vapor that does get into the attic should be dispersed and/or ventilated to keep it from accumulating and causing problems.