TL;DR
Dense-pack insulation is cellulose or fiberglass blown into closed wall, floor, or slanted roof cavities at high density, around 3.5 pounds per cubic foot for cellulose, so the material cannot settle and substantially resists airflow through the cavity. Installers drill access holes through siding or interior drywall, fill each bay with a hose until back-pressure confirms density, and patch the openings.
What it means
Dense-pack insulation is cellulose or fiberglass blown into closed wall, floor, or slanted roof cavities at high density, around 3.5 pounds per cubic foot for cellulose, so the material cannot settle and substantially resists airflow through the cavity. Installers drill access holes through siding or interior drywall, fill each bay with a hose until back-pressure confirms density, and patch the openings. It is the workhorse retrofit for uninsulated older walls, and the density target is what separates it from loose fill that slumps and leaves cold gaps at the top of every stud bay.
Where it sits in the glossary
Dense-pack insulation is part of the Trade jargon group inside the ProFix Directory glossary. Browse every term in this category from the glossary index.
Why Ohio homeowners should know it
This is a term Ohio homeowners encounter when reading contractor quotes, hiring paperwork, or inspection reports. Understanding it well enough to ask one good follow-up question is usually all the protection a homeowner needs.
ProFix Directory keeps definitions short on the index page and saves the longer context — Ohio-specific rules, where the term comes from, and which ProFix tools touch it — for these per-term pages so the term is easy to cite and easy to share.
ProFix tools that touch this term
See also
License: CC-BY-4.0 — quote freely with attribution to ProFix Editorial Team / ProFix Directory.