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Ask the Architect

More on insulation

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Q. I read your column about insulation, and wonder why foam insulation is better, why not everyone uses it, why it’s so expensive and whether there are different kinds. We just had insulation put in the walls between our family room and living room to muffle the sound when my parents play the TV too loud, and we noticed the package said R-15. What does that mean? Also, the label had tiny lettering saying there is formaldehyde in it. Should we be concerned?

A. We live in an era when computers and science accelerate our knowledge and choices. Unfortunately, with so many more choices, we can still use the wrong insulation without knowing. Basically, insulating isn’t just the material; it’s the molecular configuration that traps air in the material. Foam has the highest resistance per inch thickness.

Air entrapment keeps cool or warm molecules from directly slamming against the next air molecule and transferring temperature. By computer-simulating configurations, engineers and scientists have formulated better ways to slow transfer, keeping us warmer or cooler and our rooms quieter, but only if the right material is installed the right way.

Among the many kinds of insulation are fiberglass, cellulose fiber and polyisocyanurate foam. R-value refers to resistance. The higher the number, the greater tested resistance to thermal loss capability. If you use the wrong type or install incorrectly, it won’t accomplish the job. Foam insulation can be rigid boards or liquid-applied. Depending on the chemical composition, when the compressed liquid foam contacts air, it reacts or oxidizes, developing open- or closed-cell configurations. Less costly open-cell has half the ability to trap air as closed-cell, and is soft and spongy, while closed-cell, which contains greater amounts of dense foam, will harden, trapping more air in smaller, closer cells, also forming a water barrier.

All insulation must be uniformly and fully installed, or cold air will get in. Most installations are incomplete, with gaps where cold air gets through. A non-uniform application can’t be expected to act uniformly. A quarter-sized gap is like leaving a window open, according to the Department of Energy, which funds, studies and regulates how much insulation you were supposed to have, according to the building code.

Sound insulation works differently, does a different job and is configured differently. Did I mention that it’s different? No matter how much educational material is available and considering, with most adults having the entire world at their fingertips on their cellphones, installers often can’t get the concept right. You have thermal R-15 insulation in the family room walls instead of sound-rated insulation, so you don’t have the sound reduction you thought you would get. It’s possible to get water-based or inert insulation instead of toxic, formaldehyde-containing insulation and the thermal-resistance(R) insulation should be replaced with sound-rated batting or even better rigid insulating board that goes on the outside of the wall studs, under finish sheetrock, to avoid sound vibration transfer through the wall studs.

© 2020 Monte Leeper. Readers are encouraged to send questions to yourhousedr@aol.com, with “Herald question”  in the subject line, or to Herald Homes, 2 Endo Blvd., Garden City, NY 11530, Attn: Monte Leeper,  architect.