After a home inspection (of a tear-down rebuild in 2005), the report had a section that said:
"Fiberglass-Blown, Insulation is installed between roof rafters. 10 inches Depth factor. This is an insulation configuration that I have never seen before. It follows the old style of insulating houses. It is normally no longer done this way for a few reasons: 1) Condensation can get under the roof decking and damage the roof decking. 2) Lack of air flow under the roof decking can cause overheating of the roof shingles and premature aging. 3) You are effectively heating a larger area of the house with this insulation configuration and thus energy bills will be higher than necessary. In addition, there were no styrofoam venting baffles under the insulation so it is unknown whether there is any air space allowing any air circulation. It is highly likely that venting is blocked."
If this is the case, any guesstimate as to how much an attic insulation redo would run?