The main concern when building or inspecting a cathedral ceiling is avoiding problems with condensation, leaks, mould and damage to structural members due to poorly installed insulation.
There are typically two ways to insulate a cathedral ceiling; vented and unvented insulation. Unvented is known as “hot roof” due to lack of heat dissipation through venting. The main concern with “hot roof” method is that a hotter roof results in shorter shingle life and any leaks can cause mould and moisture issues in cavity.
Vented cathedral ceilings will either have an air space or have soffit baffles installed, which will allow for movement of air and allow heat to dissipate.
Cathedral ceilings were once very popular due to their impressive height and appearance, but ensuring proper insulation and venting has become a known issue. Inspecting your insulation is usually very limited and will typically be confined to small inspection area that may have been left open.
- Moisture Control
Installing your cathedral ceiling insulation, most people don’t realize that you have to install some form of moisture control system. The normal installation method involves putting insulation into your cavity, leaving a small area at the top allowing air to circulate. This air carries moisture with it, so that you now have a working moisture control method of removing damp from behind the insulation.
- Batt Insulation
Many insulation experts say that fiberglass batts are the worst insulation to install in a cathedral ceiling. Fiberglass allows movement of air, but doesn’t stop the moisture from penetrating behind the insulation. If you want to insulation your cathedral ceiling properly, then you need to develop another method of keeping in heat while avoiding becoming a target for mold and damp. If you do decide to use a batting insulation then you have to develop an method of preventing moisture from entering cavity.
- Dense Packing
Spray foam can prevent moisture entry while providing the insulation rating that you require. The expense of spray foam application can prevent many home owners from using this method. Fiberglass batts on the other hand are loose filled batts which allow air to infiltrate and provide insulation by providing a resistance to heat loss. Unfortunately the fiberglass also allows moist air to enter and when in contact with cooler air, (dew point) creates moisture. This is where mould and wood rotting may occur.
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