Made from ground up newspapers or wood waste, cellulose is one of the greener insulations. To resist fires, a retardant is added during its production. Cellulose is generally installed using two methods, either open blow or dense pack. An open blow is commonly used in attics, in and over the ceiling joist bays, below the rafters with no netting.
Dense pack is used in floor, wall, ceiling and rafter systems. During the dense pack instillations, netting is first installed on the inner most side of the framing to contain the cellulose within each bay. One bay at a time the cellulose is pneumatically injected through a long hose behind the netting to a density of 3.5 – 4lb’s per square foot achieving an R-vale of 3.7 per inch of depth. Cellulose usually contains a lot of small fibers that tend to pack into cracks and crevices of the closed building cavities.
With its ability to pack, and to fill holes, it forms an effective air barrier on its own. Unlike fiberglass there is no air between the fibers, this stops the loss of heat through convection. Cellulose is one of our first choices because of its ecofriendly makeup, high R-value, and effective air-barrier properties.
Blower Door tested.
Insulation R-Values Per Inch
| Fiberglass batts or blown Denspack Cellulose Icynene (low density spray foam) Expanded Polystyrene (white) Extruded Polystyrene (blue/pink) Polyurethane (spray foam or board) Polyisocyanurate (spray foam or board) |
2.4 – 3.0 3.3 – 4.0 3.6 3.6 – 4.2 5.0 5.8 – 6.8 5.6 – 7.6 |