With Dense Packing, cellulose insulation is pneumatically installed at high velocity, it acquires a unique air sealing property. In this process, the material behaves as a liquid, flowing into obscure bypasses and solidifying them. When done right, dense-packed cellulose is a highly efficient option for insulating exterior walls. It insulated as well if not better than the average batt and slows air flow through walls making your house cheaper and easier to heat and cool.