DIY dense pack insulation 2×8 walls

A homeowner building their own house asked a building science forum whether it makes sense to install wall insulation themselves rather than pay a contractor. The walls in question are framed with 2x8 studs spaced 24 inches apart, and the question centered on "dense pack" insulation — a technique where loose fiberglass or cellulose is blown into closed wall cavities at high pressure so it settles without sagging or leaving gaps over time.

The homeowner was weighing two DIY options: renting a blower machine meant for loose-fill insulation (the kind used for attics) and narrowing the hose to increase pressure, or simply compressing oversized batts — fiberglass blankets cut for thicker walls — into the 2x8 cavities instead. The motivation was straightforward: a local insulation contractor was quoting a high price, and doing the work personally could save real money.

This is a question, not a finished story, so there is no verdict here on which method works better or whether a rented blower can match a contractor's equipment for proper density. For a homeowner thinking about their own walls, the takeaway is simply that dense-pack insulation is a specific technique with real performance requirements, and the tools available to rent may or may not be built to achieve it. Anyone facing a similar insulation job with thick wall cavities would want to understand what density and coverage the insulation needs to perform as intended before deciding between a rental approach and hiring it out.