(Welcome to Anthony, one of the finalists in our Green Architect blogger search. He's writing from Brooklyn. Comment away!)
Cellulose is sexy! Or at least better to the touch than most insulation materials. Cellulose is one of the oldest insulation materials to be used in buildings, but it has changed considerably since old newsprint was stuffed into wall cavities at the turn of the last century. The pulp is finely ground and sprayed with a flame, mold, and rodent retardant, typically boric acid. This treatment has satiated many of the historic concerns about using the material, namely the combustibility of paper and the fear of multiplying mice in your walls...
The installation process happens in two ways, a dry loose-fill method and spray-applied. The loose-fill is typically used for rehab work, as only one hole in each wall stud bay is required to fill the material (which can be done from the inside or the outside of the house). This method is prone to settling inside the wall, reducing its effectiveness to about 80%. The spray-applied method has a higher initial moisture content to insure cohesion, and is sprayed between the studs in new construction, typically using a light mesh web which is stapled up to contain the material.
Old newsprint has gained new momentum as the insulation material of choice in recent years over the rising costs of energy and concerns about the environmental impact of some other insulating materials. It has an R-value of between 3.6 and 4 per inch (comparable to fiberglass), R-value being a measured value of heat resistance, where the higher the number, the more insulating the material. Cellulose is made up of up to 80% recycled content (which is mainly newsprint), and will naturally decompose at the end of its life cycle. While insulation is one of the easiest and cheapest ways to Green your home, it rarely gets the attention it deserves as it is hidden away inside the wall.
Give cellulose some love!
Photos by Anthony Harrington