Non Vented Attic System

Control construction moisture content with tenting or temporary roofing when necessary.

Non vented attic system.

The attic space becomes indirectly conditioned as a result of the air leakage heat transfer and vapor diffusion through the ceiling. In order for an un vented roof assembly to function properly the following conditions must be in place. Because the drying capacity of unvented roof assemblies is inherently lower than vented ones it is especially critical to control built in moisture during construction. Un vented roofs operate on the principle that moisture entering the roof assembly can be controlled and that there is no need for venting to control moisture accumulation.

It is a common misconception that one of the unvented attic problems is that the roof needs to breathe or that the insulation will make the roof hot. The unvented attic space is completely contained within the building thermal envelope. 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. 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.