I’d like thoughts on my attic dilemma.  I’ve been a GBA reader for about a year and from what I’ve gathered, my roof/attic assembly was originally built to be vented and has old fiberglass bats (R15-R19), but to insulate to today’s standards I’m stuck at the vented vs conditioned fork in the road.  Currently we have a ridge-line vent in the primary roof with soffit vents all around.  The one side of the main attic can mostly vent to ridgeline via the soffit vents along the one side, but the other side connects to a flat attic and the bedroom attic as a hip.

I would really like to blow in the max amount of cellulose up to R-60 where space allows keeping the attic vented.  Seems like the most cost-effective and energy conserving.

But after reading some, it seems the flat attic over the mudroom and the two hips created by the master bedroom and the porch may mean that our roof isn’t “simple” and it would be best unvented, but I’m concerned of the fiscal implications and complexities with moving the insulation and air barrier to the roofline.  I am a believer in air sealing the flat attic floor and blowing in cellulose.

For example, if we blow in R-60 worth of cellulose in the main attic, the smaller flat attic of the mudroom won’t be able to breath up into the larger main roof and then stagnant air/moisture may accumulate in the flat attic, unless we had long connected baffles that went from the soffit in the flat attic, all the way up to the main ridgeline.

After an energy audit and blower door test, the contractor recommended “dense” packing the flat attic and sealing off the soffit vents.  But wouldn’t moisture from inside the house over time drift up into the dense pack?  AKA, dense packing doesn’t create true air sealing.  Am I missing something here?