Do you have
questions about
your roofing project?
Click Here to
see Comments
From Our
Proud Member Of
The Following
WARNING: Chemicals
known to the State of
California to cause cancer,
birth defects, or other
reproductive harm are
created by the combustion
of propane, use of hot tar
kettles and tar products.

Our industry is required to
comply with Proposition 65
known as the California
Heath And Safety Code. We
are required to give you
this warning.
Blanket (Batt and Roll) Insulation

Blanket insulation—the most common and widely available type
of insulation—comes in the form of batts or rolls. It consists of
flexible fibers, most commonly fiberglass. You also can find
batts and rolls made from mineral (rock and slag) wool, plastic
fibers, and natural fibers, such as cotton and sheep's wool.

Batts and rolls are available in widths suited to standard
spacing of wall studs, and attic or floor joists. Continuous rolls
can be hand-cut and trimmed to fit. They are available with or
without facings. Manufacturers often attach a facing (such as
kraft paper, foil-kraft paper, or vinyl) to act as a vapor barrier
and/or air barrier. Batts with a special flame-resistant facing
are available in various widths for basement walls where the
insulation will be left exposed. A facing also helps facilitate
fastening during installation. However, it's recommended that
you use unfaced batts if you're reinsulating over existing

Standard fiberglass blankets and batts have a thermal
resistance or R-values between R-2.9 and R-3.8 per inch of
thickness. High-performance (medium-density and high-
density) fiberglass blankets and batts have R-values between
R-3.7 and R-4.3 per inch of thickness. See the table below for
an overview of these characteristics.

Thickness (inches)        R-Value        Cost (cents/sq. ft.)
3 1/2                                 11                    12-16
3 5/8                                 13                    15-20
3 1/2 (high density)             15                    34-40
6 to 6 1/4                           19                    27-34
5 1/4 (high density)             21                    33-39
8 to 8 1/2                           25                    37-45
8 (high density)                   30                    45-49
9 1/2 (standard)                  30                    39-43
12                                      38                    55-60

Table 1. Fiberglass Batt Insulation Characteristics*

Installation -
The maximum thermal performance or R-value of blanket and
batt insulation depends heavily on proper installation.
Therefore, it's best to have a certified insulation installer do it.
If you'd like to have it done professionally, you should do the
•        Obtain written cost estimates from several contractors
for the R-value you need. Don't be surprised to find quoted
prices for a given R-value installation to vary by more than a
factor of two.
•        Ask contractors about their air-sealing services and
costs as well, if needed.

To evaluate batt installation, you can measure batt thickness
and check for gaps between batts.

If you want to install the insulation yourself, carefully follow
instructions and the necessary safety precautions. The
insulation's manufacturer may offer instructions. You should
also check your local building and fire codes. Please see the
Installation and Reading List resources on the right side of this
page (or below if you've printed the page).

Blanket (batt or roll) insulation and installation usually costs
less than other types of insulation.
What you
Need to
know about