In existing homes, where wall cavities are closed up with siding on the outside, and drywall, plaster, or some other finish on the inside, good insulation becomes problematic. How do you fill the whole cavity when the cavitiy is already closed?
A great way is with “dense packed” cellulose insulation. Cellulose insulation is essentially ground up paper (e.g., newspaper) with fire retardants added. We like 100% borate retardant–low toxicity and critters don’t like it.
In yesteryear, cellulose was essentially poured (loosely blow) into wall cavities. The challange with this was that the cellulose settled over time, leaving a gap with no insulation at the top. Dense packing overcomes this and is a great way to insulate walls in existing homes. First, the loose fill insulation fill nooks and crannies and does a great job filling cavities, providing the type of coverage you need for insulation to be effective. Second, dense packing actually pumps insulation into a cavity a higher density than it would settle to. Thus, over time we don’t see additional settling. In fact, the insulation is in there so tight, it generally doesn’t fall out even when you take the wall covering down. In the picture, you see the wall I just removed this weekend as part of a major bathroom remodel. And you see how the cellulose completely filled the wall cavity (less a few holes from my hammer as a pulled the plasterboard down). And the insulation is packed so well, that is stays in place even without the plasterboard covering it. [Good job, Tom, Joe, and Jason.]
Good stuff. Works great! A practical solution for those wanting to make their homes more efficient. (I’m still amazed how many homes have little or no insulation in their walls.) And this insulation qualifies for the $1,500 tax credit currently avaiable for energy-efficiency retrofits.