Attic Conditioned Space

Most updated central air conditioned homes have a new air conditioner split system meaning the ac is broken up into parts.

Attic conditioned space.

Though it s against building code to vent any kind of exhaust to an attic space many home builders have gotten away with this shortcut. An unvented attic assembly a k a. Compact assembly or hot roof ventilated roof assembly. The intended purpose was to allow warm air and moisture to escape.

The loss of energy efficiency means some designers choose to move the ductwork into the conditioned areas of the home and leave the attics unvented. An outdoor unit which houses the fan condenser and compressor and an indoor unit which holds the evaporator and fan. Making the attic a conditioned space taking the building envelope to the roof is a good approach and will save energy another approach is to use radiant coated deck sheathing seal all ceiling attic penetrations and blow in r 60 insulation as it will cost less than spray foam and should give at least the same energy efficiency to the home. A fundamental requirement of an unvented attic assembly is the use of air impermeable insulation on the underside of the unvented roof to prevent air infiltration and exclude airborne moisture from the attic.

Building america research has demonstrated unvented conditioned attics can substantially improve energy performance while allowing home builders to continue locating hvac systems in the attic space. The thermal boundary can be at the ceiling plane leaving the attic space above uninsulated and vented or the thermal boundary can be located at the roof line creating a sealed insulated conditioned or semi conditioned attic space. You can insulate the rafter space provided that you leave a ventilation space between the top of the insulation typically fiberglass batts or blown cellulose and the underside of the roof sheathing section r806 1 ventilation required. Attic hvac systems save space.

If you re considering turning your attic into conditioned storage or living space it s worth changing tactics to insulate between the rafters and wall joists instead of the floor. Well mainly it s a way to save space. You can use rigid foam. The attic space becomes indirectly conditioned as a result of the air leakage heat transfer and vapor diffusion through the ceiling.

In warmer climates unvented attics can prevent the condensation that occurs on ductwork in some vented attic spaces. Traditionally building codes have required attic ventilation.