In this photo see beginning of rapid and easy change. The scattered temporary plywood is important to my safety. I have cut down a horrible 16" OSB skirt about the small access hole.
In this access exercise, learn some lessons about HVAC duct installation, attic ventilation and a further thoughtless neglect of access. Preserving duct length is very important as ducts are disassembled and reset. Yet, I must sacrifice about 6" from each flex duct at this wye, because of remnant bad advice of PTCS trainers in the service area of Bonneville Power Administration. Goop, no longer required, should never be applied for liner attachment.
Goop applied blindly and in risk of clothing, missed this under-side zone of the main branch of the wye. There was duct leakage, out of sight. UL181 Nashua 557 tape easily achieves zero leakage here, and is the right choice for easiest damage-free separation of ducts for maintenance or replacement. Know that flexible ducts have claimed useful service life of not more than ten years . See example of Thermaflex ducts as fallen-apart rat paths after about 25 years .
I know that regardless of found condition, I must replace cardboard soffit vent baffles. They rarely survive more than thirty years and when used are with no manufacturer thought or guarantee of acceptable service life (sixty years!). Here I have more than conscience in play. Curl with detached flimsy staples is ugly. Looking down at vent bird block, see poor bird block design employed by most builders. Slot placement demands vent baffles 3 1/2" down from roof sheathing, a large sacrifice of potential insulation depth over exterior wall headers. This bird block is needed in every available roof joist bay, not in every fourth.
Lumber for proper soffit vent baffles is free, in good employment of job scrap. Use 25 cents of good deck screws, not nails. I assembled six baffles in thirty minutes. This is quicker than setting a $1 cardboard baffle, thus less expensive. Wood sleds are easily adapted for obstructions, then set much more securely.
Baffles just 32" tall are ample over R45 batts. I can push R30 top-layer batts tightly against a baffle, for fullest insulation value, and that is the controlling economy.
A hidden attic around this corner was uninsulated too. The triangular access is new. Opportunity was concealed behind redundant OSB sheathing.
While I am at this I will insulate over the garage too, to just R15. I can't bear to crawl there carrying insulation, through this jungle of beam and variable trusses.
Cut in a new access for the garage, "factory built" in my shop. Where truss bottom elements are 2x4, they must not carry loads unless strengthened as composite beams. Leave a couple of 9" rips of plywood that I needed for my safety, but not more flooring.
Here is the fully-dimensioned plan of my hatch, offered to anyone as noted here.