Cellulose Insulation - History of Cellulose Insulation

History of Cellulose Insulation

Cellulose is the oldest building insulation material. Many types of cellulosic materials have been used, including newspaper, cardboard, cotton, straw, sawdust, hemp and corncob. Monticello was insulated with a form of cellulose. Modern cellulose insulation, made with recycled newspaper using grinding and dust removing machines and adding a fire retardant, began in the 1950s and came into general use in the US during the 1970s.

The market for insulation increased following the oil embargo of 1973-74. The embargo caused energy costs for heating to skyrocket across the nation, which led to increased interest in energy conservation measures. Insulation gained significant national attention as a cheap and available technology to increase the energy efficiency of homes. In 1977, following a particularly severe winter, a tax credit was given for homeowners who installed insulation.

While in 1976 there were roughly 100 cellulose insulation firms with 125 plants, by 1978 there were more than 350 firms with more than 500 plants1. Cellulose insulation was produced locally by small manufacturers who purchased ready-to-operate machines and offered a cheap and easy low-tech production process. Other than some constraints created by a shortage of boric acid for use as fire retardant, cellulose captured an increased share of the market due to lower costs and its suitability for retrofits. Meanwhile fiberglass and rockwool producers found it difficult to keep up with the demand for insulation from their customers.

Due to complaints by retailers, contractors and consumers about price, safety and quality control problems, the federal government began enacting insulation standards beginning in 1978. There was a great concern that the growth in cellulose manufactures was leading to improperly or insufficiently treating insulation against the threat of fire even though reliable statistics on a national basis did not exist. This led to the Federal Consumer Products Safety Commission passing 16 CFR Part 1209, which sets safety standards covering four product attributes for cellulose insulation only: settled density, corrosiveness, critical radiant flux and smoldering combustion. Another regulation passed was the “R-value Rule,” placing clear limitations on the claims that manufacturing and marketing firms can make about their product.

The effect of regulations by the CPSC put most of the small producers of cellulose insulation out of business. The costs incurred by increasing fire testing made cellulose more expensive and the bad publicity helped decrease demand. They were either unable to meet the testing requirements or they merged with other small manufacturers. In 1985 the CPSC asked Congress to repeal the flammability standard after further studies. By 1991 only 61 cellulose producers still remained in the US.

The fiberglass industry meanwhile benefited from most of the regulations passed by the federal government. The heavy lobbying by the more centralized fiberglass and mineral insulation manufacturers helped pass the tough fire standards for cellulose insulation. These standards were reinforced by technical bulletins published by the Mineral Insulation Manufacturers Association (currently known as the North American Insulation Manufacturers Association) that promoted fire hazard claims against cellulose insulation. These claims were not independently verified, faced little scientific review, and were misleading and untrue.

Currently cellulose insulation has increased again in use in the United States. Part of the reason for this growth are studies that suggest that cellulose may actually protect a building from damage in a fire better than fiberglass because cellulose is denser than fiberglass and doesn't allow the oxygen necessary to burn structural members. Several National Research Council Canada studies have backed these claims. Another major reason for the comeback of cellulose might be because of the increased interest in green building. Cellulose has the highest recycled content of any insulation material and also has less embodied energy than fiberglass and other furnace produced mineral insulations.