Change A Vented Attic To An Unvented One

An unvented attics is one where the air vapor and thermal controls are installed at the roof deck.

Change a vented attic to an unvented one.

Install insulation along the underside of the roof deck of an unvented attic rather than on the ceiling deck of a vented attic for either of two reasons. From my research it looks like the best option is to make the attic a conditioned nonvented space. Vented roofs serve a number of different purposes and their roles vary from climate to climate. 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.

When insulating your attic the contractor can either spray the attic floor to keep a vented attic or spray the roof deck for an unvented system. If there is a vapor retarder on the attic floor it shall be removed to allow any moisture that builds up in an unvented attic to diffuse into the house below. A secondary goal is to vent moisture that infiltrates the attic from the conditioned home. Currently the attic is vented and has zero insulation anywhere.

I live in maryland and own a house that has the hvac system in the attic. I ve been researching several methods to insulate my attic. However you do not describe the potential uses for that space and that gives me pause as to how to properly evaluate the risks of your options. The attic space becomes indirectly conditioned as a result of the air leakage heat transfer and vapor diffusion through the ceiling.

Your stated goal is to turn your attic into a non vented conditioned space. To provide an unvented conditioned space for locating hvac equipment in the attic and or to provide a continuous thermal barrier for designs that have complex coffered ceiling planes and or numerous penetrations for lights speakers vents soffits etc which make it difficult to achieve an airtight ceiling plane. If you planned to leave the open cell foam exposed to the attic it would certainly dry to the inside much more easily. Let s dive a little deeper into what that means exactly.

I m unsure of what to do and i m unsure of the most. In colder climates the main purpose of a vented roof is to keep the roof cold and reduce the formation of ice dams. A vented attic system refers specifically to having working vents in the attic.