Cellulose insulation and the process of weatherizing and insulating a building involves a number of technical terms and concepts. We've compiled this glossary to help you decipher them.
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Settled density refers to the final density of a material after a period of time, allowing for natural settlement, vibration, the effects of gravity, etc. It is the density of a material after these natural settlement processes have concluded. Cellulose insulation has a settled density of app. 1.5 lbs. per cubic foot.
Smoke Developed Index
Spray applied cellulose
Sprayed Foam Insulations
Open cell/Low Density, Closed Cell/High Density
Stabilized Cellulose Insulation
Cellulose insulation that contains additional amounts of starch or binders that when activated with moisture allows the cellulose, in theory, to be applied in an attic loose-fill application and not experience any settling.
Stack effect is the movement of air into and out of buildings, chimneys, flue gas stacks, or other containers, driven by buoyancy. Buoyancy occurs due to a difference in indoor-to-outdoor air density as a result of temperature and moisture differences. The result is either a positive or negative buoyancy force. The greater the thermal difference and the height of the structure, the greater the buoyancy force, and thus the stack effect. The stack effect is also referred to as the 'chimney effect', and it helps drive natural ventilation and infiltration.
The Sound Transmission Class (STC) rating is a single-number rating of a material's ability to resist airborne sound transfer at the frequencies 125-4000 Hz. In general, a higher STC rating indicates better airborne sound attenuation
performance than the same or similar material with a lower rating. Dense-packed cellulose insulation has a higher STC rating than either glass fiber or sprayed foam insulations.
An agent that reduces the surface tension of liquids so that the liquid spreads out, rather than collecting in droplets.