Wall frames are hollow letting air flow freely between the walls and up into the attic.
Fully sealed attic.
The energy savings touted by unvented attics can be as high as 20.
Unventilated attics can help to mitigate energy loss through leaky ducts or ceiling fittings.
Sealed and insulated the attic hatch helps keep heat in.
Attic insulation shall be installed at all flat and sloped surfaces adjoining the conditioned space with less than 2 gaps voids and compressions and at levels that meet or exceed prescriptive levels specified by the 2012.
All joints cracks and penetrations in the wall air barrier shall be fully sealed with caulk foam or equivalent.
The number one prep step.
It also prevents unwanted critters like raccoons from moving in.
Gaps in the attic or between the lower floors and the attic will let heated or cooled air escape to the great unconditioned outdoors making any insulation you add essentially useless.
However if moisture is able to enter the unvented attic space it may lead to roofing panel issues.
Jump ducts which do not directly deliver conditioned air from the hvac unit may be located in attics if all joints including boot to drywall are fully air sealed with mastic or foam and the jump duct is fully buried under the attic insulation.
Sealing attic hatch attic door to properly seal your attic hatch also known as an attic door or scuttle hole at a minimum you should apply weather stripping and ensure the attic side of the attic door is insulated.
Find a diagram of common air leaks here here s a quick primer on fixing draft prone spots.
Sealed attic construction by excluding vents to the exterior can be a good way to exclude moisture laden outside air from attic and may offer a more easily constructed alternative for air leakage control at the top of residential buildings.
Ducts are located within an unvented crawl space.