Change A Vented Attic To An Unvented One

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.

Change a vented attic to an unvented one.

Currently the attic is vented and has zero insulation anywhere. Let s dive a little deeper into what that means exactly. I ve been researching several methods to insulate my attic. Vented roofs serve a number of different purposes and their roles vary from climate to climate.

An unvented attic is one which is not ventilated and this is important one where the ceiling has complete air vapor and thermal controls in place. All openings that exist to ventilate the attic including ridge vents gable vents and soffit vents shall be closed off and sealed and new roofing installed as needed. 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. In colder climates the main purpose of a vented roof is to keep the roof cold and reduce the formation of ice dams.

I live in maryland and own a house that has the hvac system in the attic. And i mean completely intact. An unvented attics is one where the air vapor and thermal controls are installed at the roof deck. If you planned to leave the open cell foam exposed to the attic it would certainly dry to the inside much more easily.

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. From my research it looks like the best option is to make the attic a conditioned nonvented space. 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. 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.

I m unsure of what to do and i m unsure of the most. A secondary goal is to vent moisture that infiltrates the attic from the conditioned home. 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.