Glossary · Insulation & windows
Dense-pack insulation
Also called: dense-pack · dense-packed · dense-packing · dense-pack cellulose
Loose-fill insulation, usually cellulose, blown tightly into closed wall cavities through small holes so it fills them, resists settling and slows air movement.
What it means
An installer drills small holes, typically ⅝ to 2 inches across, into each cavity and fills it through a hose until it's packed firm. A typical dense-pack density for cellulose is about 3.5 pounds per cubic foot; too little leaves voids that settle, and too much can make walls bulge. It's a common way to insulate empty walls in older homes without opening them up.
Why it matters in an audit
Dense-packing can add insulation and cut air leakage in uninsulated walls, but knob-and-tube wiring and moisture problems have to be dealt with first.
Typical numbers
Reference values with their sources. Your auditor’s report gives the figure for your own house.
| What | Value | Source |
|---|---|---|
| Typical dense-pack density (NRCan) | Cellulose about 3.5 lb/ft³; fiberglass about 2.5 lb/ft³ | natural-resources.canada.ca ↗ |
| Holes (NRCan) | 15–50 mm (⅝–2 in.), usually one to five per cavity on each floor | natural-resources.canada.ca ↗ |