Insulation attic ceiling slope

[alpito]

My son has an older home with a finished attic. The ceiling slope was covered with 4 X 8 sheets of something that looks like plaster with a fibrous (almost crumbly) material on the backside. These sheets look like what I think is called 'buffalo board'. I don't know what it is, but I think there has been a plaster applied over this board whick made it quite heavy. These sheets were applied with nails. They are falling off and sagging along the whole attic room. I noticed that there is nothing else behind these sheets, and you can see all the ceiling joists with the corresponding perpendicular roofing "boards.

Is there a way to apply an insulation to attic ceilings without blocking flow from the soffit vents (they are present). I didn't see any shutes for air flow, but there is a cellulose layer overlying the horizontal soffits, and I assume continuing under the attic floor , although I can't see under the attic floor. But mainly, how do we insulate the ceiling and appropriately cover it. Thanks, Alpito

[flickit]

My son has an older home with a finished attic. The ceiling slope was covered with 4 X 8 sheets of something that looks like plaster with a fibrous (almost crumbly) material on the backside. These sheets look like what I think is called 'buffalo board'. I don't know what it is, but I think there has been a plaster applied over this board whick made it quite heavy. These sheets were applied with nails. They are falling off and sagging along the whole attic room. I noticed that there is nothing else behind these sheets, and you can see all the ceiling joists with the corresponding perpendicular roofing "boards.

Is there a way to apply an insulation to attic ceilings without blocking flow from the soffit vents (they are present). I didn't see any shutes for air flow, but there is a cellulose layer overlying the horizontal soffits, and I assume continuing under the attic floor , although I can't see under the attic floor. But mainly, how do we insulate the ceiling and appropriately cover it. Thanks, Alpito
...of the right width should unfold right between the ceiling joists and if you don't have any problems with excess moisture entering through the soffits, push them in as close as possible without impeding the air flow. You can use a few Simpson insulation supports between the ceiling joists near the rafter ends to form a makeshift shute to allow for more airflow without installing a chute. The insulation vapor barrier must face down towards the living space. You can also use the existing cellulose, rake it away from the rafter ends and cover the space between the ceiling joists with visquine to form a moisture barrier and at the same time form the air chute you mentioned. This can be difficult due to minimal working space at the roof ends and may be better performed from the outside by removing the soffit screen covers. Watch out for 'attic dwellers' and any electrical wiring you might trip over. Be safe and good luck!