Product description

Fiberglass blanket insulation is made from sand (Si02), limestone (CaC03), and sodium carbonate (Na2C03) and is usually the least expensive insulation on the market for the insulating value achieved.2 Because it is inorganic, it will not rot or absorb moisture, is noncombustible, and does not support the growth of mildew, mold, or fungus. The North American Insulation Manufacturers Association (NAIMA) recommends the use of fiberglass insulation that meets the requirements of the current edition of American Society for Testing and Materials (ASTM) C665 Standard, “Specification for Mineral Fiber Blanket Thermal Insulation.”

Each type comes either in continuous rolls or in packages of pre­cut lengths called batts (Fig. 8.1). Relatively easy to install, both types are roughly equal in price per square foot. The decision to purchase batts or rolls depends on the specific application and/or preference of the installer. This is covered in more detail later in this chapter.

Batts and rolls are manufactured for standard joist and stud spacings. Lengths of batts available include 47, 48, 90, 93, 94, and 96 in. Rolls are available in lengths of 39 ft 2 in, 40 ft, and 70 ft 6 in. Widths of rolls and batts can be found in the following sizes: 11, 15, 15V4, 16, 23, 23/4 and 24 in.

Nominal Dimensions Available

Batts

Rolls

Lengths

47" (1194 mm), 48" (1219 mm) 90" (2286 mm), 93" (2362 mm) 94" (2388 mm), 96" (2438 mm)

397" (11.94 M) 40′ (12.19 M) 70V (21.49 M)

Widths

11" (279 mm), 15" (381 mm) Ш" (387 mm), 16" (406 mm) 23" (584 mm), 23%" (590 mm) 24" (610 mm)

11" (279 mm) 15" (381 mm) 23" (584 mm)

Figure 8.1 Typical sizes of batts and rolls. (NAIMA)

Fiberglass does not take up water within the glass fibers, but water vapor passes freely between the fibers. Therefore, fiberglass insulation must be used in conjunction with a vapor barrier placed on the appropriate side. Batt and roll insulation is available unfaced or with a facing already attached. Unfaced blankets are used in conjunction with a polyethylene vapor barrier where applicable. The most common facings available for blanket prod­ucts are kraft paper and foil (Figs. 8.2 through 8.5).

All manufacturers of fiberglass insulation products provide per­formance and installation information such as R-value, number of

Product description

Figure 8.2 Unfaced batt. (CertainTeed)

Product description

Figure 8.3 Kraft paper-faced batt. (CertainTeed)

Product description

Figure 8.4 Foil-faced batt. (CertainTeed)

Batt Insulation Characteristics

Thickness

(inches)

R-value

Cost

(♦/sq. ft.)

3 4i

11

12-16

35/fe

13

15-20

15 (high density)

34-40

6 to 6V4

19

27-34

5V4

21 (high density)

33-39

8 to 84i

25

37-45

8

30 (high density)

45-49

9

30 (standard)

39-43

12

38

55-60

This chart is for comparison oniy. Determine actual thickness, R-value, and cost from manufacturer or local building supply.

Figure 8.5 Typical cost.

pieces per package, coverage per bag, size, and type either on preprinted bags or on labels attached to generic bags.