Hello –

I had an energy audit done and have a question about one of the points that the inspector brought up.  We have a ranch style house with an attached garage.  The garage wall and ceiling have fire-rated drywall.  There is an attic space above the garage and an attic space above the house.  Currently, these two attic spaces are separated by plywood – with an approximately 4×4 hole for a person to crawl though because the access to the attic is only through a hatch in the garage.  The energy audit report said that we should cut larger holes in this plywood – meaning the plywood between the house attic and the garage attic – so that the airflow between to the two areas is better.  Not that I disagree at all, but I’m just wondering the why.  My layman thoughts would be that although the garage is insulated, there no actual heat/AC in there so it’s colder in the winter and warmer in the summer – so the attic above the garage is also colder/warmer.  And we’d want the to keep that colder/warmer air more over the garage vs over the house (so the house can more easily stay warm in the winter and cool in the summer).  The audit findings said that the roof sheeting under the active roof is impeding airflow which can cause heat and moisture getting trapped in the roof and increased temperatures.  Before we take a saw and cut large holes in this plywood wall between the garage attic and house attic – I’m just trying to understand the details a bit more.  For climate, we are in the upper Midwest (i.e. where we get real winter but July/August can be quite humid and hot).  Thanks!