Similarly, controlling sound transfer in buildings wasn't much of an issue when households were separated by open space or commercial buildings were made of solid masonry and concrete.  As occupancy densities, uses, and construction techniques changed the need arose for isolating sounds from adjacent spaces and uses. Insulation emerged again as a way to reduce sound transmission in hollow partitions and stud framed wall assemblies. Since sound energy and heat energy are found to flow very similarly, insulation has traditionally been, and continues to be, one of the best ways to control the transfer of both heat and sound into or out of buildings.

Properly filling cavity walls with insulation can effectively reduce heat and sound flows through the walls. Photos courtesy Bonded Logic Inc.

 

In addition to the basic thermal and acoustic properties of these materials, however, other factors have always been important in identifying suitable product choices. Building codes for example have always required that materials have predictable fire ratings. Yet most traditional insulation is combustible giving rise to the need for added treatments to achieve the needed and acceptable fire resistance. Similarly, some insulation materials were found to harbor mold or mildew if they became wet requiring other treatment along with installation care and attention to avoid this unwanted condition. Along with these important characteristics, insulation also needed to be appealing to building owners, designers, and buildings, but not to unwanted pests that might eat or live in the warmth of an insulating material. Deterrents to rodents, insects, and other pests became increasingly important whenever materials surrounding the insulation could be compromised or invaded.

Even with all of these different demands and requirements, insulation has traditionally been regarded as a fairly straightforward building material that is simple to install, relatively low priced, and capable of quick paybacks in energy savings or other benefits. While these features remain true today, a number of other trends and practices have emerged during the last 30 years that directly affect the way architects specify and contractors install insulation products. The lessons learned along the way have included the disappearance from the market of certain problematic products for various reasons, such as:

• Some spray type insulation was found to "out gas" or emit fumes long after the installation making occupants sick or worse.
• Insulation with asbestos containing materials had great thermal properties, but health risk issues that are all too well known.
• Insulation board used outside of the cavity wall and finished with synthetic stucco, when installed improperly, was found to cause significant moisture and water penetration problems, particularly in warm climates.

Other issues emerged along the way indicating a need for special attention in determining how insulation fit into the larger design of the building:

• Air barriers and vapor retarders became important but often controversial responses to some of the increased uses of building insulation since different conditions and different products would dictate different choices for these related materials.
• Overall indoor air quality became increasingly important particularly under the assumption that "tighter" buildings couldn't "breathe" allowing indoor air pollutant levels to rise.
• Global issues of embedded energy in building products suggested that insulation manufacturing was consuming more energy than it was saving in some cases.
• While manufacturer's test data was reliable for freshly manufactured insulation, performance was found to diminish over time in some products.
• Similarly, test data was based on properly installed insulation whereas actual field installations were found to vary, sometimes significantly, giving rise to a concern over quality control of the completed construction.

All of the issues and information described above have led to an increasingly mature and sophisticated building insulation industry with new products that have been updated, improved, and tested to eliminate some of the problems and address the current needs of buildings. However, it is important that architects, designers and contractors are using current and complete information when making decisions about insulation or they risk not only being out of date, but creating poorly performing buildings.