Unvented Attic Air Exchanger

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.

Unvented attic air exchanger.

Now my house is an 1100sq ft bungelo. The unvented attic space is completely contained within the building thermal envelope 2. No interior class i vapor retarders are installed on the ceiling side attic floor of the unvented attic assembly 2012 irc 3. We are going to address the idea of air exchange in closed attics that use open cell foam.

The energy savings touted by unvented attics can be as high as 20. Summer attic air temperatures with old terra cotta colored asphalt shingles peaked at 140 to 145 at 18 above the blown in fiberglass insulation layer at the attic floor. Summer attic air temperatures with reflective roof peak at or slightly above outdoor air ambient. No interior vapor retarders are installed on the ceiling side attic floor of the unvented attic assembly 2009 irc.

Building codes require unvented attics to have air impermeable insulation in contact with the roof sheathing. The risk is condensation or mold on the underside of the sheathing. We currently have an old 1980s air exchanger in our attic split entry 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.

But what i m trying to determine is should we go out of our way to change all the duct work and install the hrv in our basement. Unventilated attics can help to mitigate energy loss through leaky ducts or ceiling fittings. This is because the top floor ceiling is no longer the air barrier for the house the spray foam at the roof deck underside in the attic is the air barrier. Or can we keep all in the attic.

Obviously it would be way easier just to keep it all in the attic and save room but i want to do what is best. Where wood shingles or shakes are used a minimum inch vented air space separates the. It often takes until early to mid afternoon for this peak to occur. In an unvented attic penetrations through the ceiling directly below the attic do not need to be air sealed.

However if moisture is able to enter the unvented attic space it may lead to roofing panel issues. The problem that can occur in a closed attic assembly is the management of the moisture that rises and accumulates in the attic space. It s most likely to occur after periods of mild wet weather followed by an overnight cold snap. Or if high humidity bathroom air finds its way into the attic through.

Looking at an air to air exchanger its made by venmar its a constructro 1 5.