Fiberglass
Consists of extremely fine glass fibers and is one of the most ubiquitous insulation materials.
Manufacturers now produce medium- and high-density fiberglass batt insulation products that have slightly higher R-values than the standard batts. The denser products are intended for insulating areas with limited cavity space, such as cathedral ceilings.
HOW IT'S MADE
Fiberglass insulation is made from molten glass that is spun or blown into fibers. Most manufacturers use up tp 40% to 60% recycled glass content.
THE RIGHT CHOICE MATTERS
High-density fiberglass batts for a 2 by 4-inch (51 by 102 millimeter [mm]) stud-framed wall has an R-15 value, compared to R-11 for "low density" types.
A medium-density batt offers R-13 for the same thickness.
High-density batts for a 2 by 6-inch (51 by 152 mm) frame wall offer R-21, and high-density batts for an 8.5-inch (216-mm) spaces yield about an R-30 value.
R-38 batts for 12-inch (304-mm) spaces are also available.
