Area was existing when I bought it. I added some supplies and a return for the HVAC.
Ok in the winter... too hot in summer. I found the rafters on the one side had no insulation(above the drywall) and the other had. The short section in the middle also had none.
The rafters go down to the perforated soffit. Have gable ends.
I've read that I need to allow an 1" space between insulation and the roof sheating for air flow. But my contractor friend says to have insulation blown in there and completely fill rafter areas and increase the size of the one gable end(too small). He says not completely filling area...leaving the gap...I would create moisture. Basically explained as the warm the the roof would meet with the cooled or cooler insulation below..it would get wet??

Side note: I replaced the wooden sealed soffit last year with aluminum. I punched an 1" hole in the wooden soffit about every foot throughout.


In additional to this I've added answers to some questions.

First: The ceiling center(short section about 3 feet wide) is also not insulated.
Second: I had a bigger furnace/AC put in because I knew I needed it for this space. Trane, the contractor, also but in the supplies and return.
Third: I have experimented with supply and return closing/opening and currently have returns on first floor closed and a couple of the supplies on the first floor closed as well.
Fourth:I looked at the other used end of the second floor and found the insulation in the rafters down about an inch or so from the roof sheathing,it a little warm there but not to unbearable. Both sides are insulated as well as the center.

Question: Would filling rafters with insulation take away from the life of my roof?

Yes. Think of pouring a glass of iced tea. On a hot day, the outside of the glass sweats. The water doesn't come out of the tea, but from the humidity in the surrounding air. So anytime there is a difference in temperature between outdoors and indoors your roof will be sweating. You leave a gap between the roof and the insulation so the insulation does not wick up this moisture and become wet, because wet insulation does not insulate well. The fiberglass type with the Kraft paper has a vapor barrier {the paper} to prevent it's getting wet. You always put the vapor barrier against the cold side. There are cheap styrofoam type pans available that you can just staple to the underside of the roof to gap your cellulose filll away from the roof. In the winter time this moisture will freeze and it will use up heat energy from your house that you are paying for to do it. Water uses a lot of energy to freeze. So keeping that sweaty roof well insulated where it doesn't freeze and thaw saves money.And your roof itself will stay cooler with an air layer insulating it. When the shingles are hot they are more flexible and can be more easily dislodged by high winds etc.

Wildandblue's answer is pretty detailed and accurate except I think he meant to say to put the vapor barrier on the warm side of the insulation. This is especially true in the colder climates where the temperature difference between inside and out is relatively large in the winter time. The idea is to keep the warm moist air that is inside the house from leaking through the wall and getting chilled to the point where condensation forms causing the wet condition that you want to avoid in the insulation and underside of the roof deck. If the vapor barrier is on the cold side of the insulation, the warm moist air from inside the home can come into contact with the cold vapor barrier and condensation will form continuously during cold days and can cause rot and fungus formations to occur.