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2018 National Home Improvement Estimator, All Rights Reserved Page 79

Chapter 5, Insulation and Moisture Control

Homes built before the early 1970’s were designed in an era when gasoline was less than 30 cents a
gallon, heating oil was cheap and natural gas supplies were plentiful. Few people worried about energy
efficiency because there was energy to spare. Builders and homeowners didn’t spend money on
insulating houses because it was cheaper just to turn up the heat. But times have changed. Modern
insulation standards are considerably higher.

Ceiling Insulation
Most homes have an accessible attic with exposed ceiling framing. That makes it easy to check the
depth of insulation and apply more when needed. Before about 1970, the most common attic insulation,
if there was any, was reflective foil (in warmer climates) or a few inches of rock wool (in colder climates).
Optimum insulation still varies with location. But homes in milder climates can benefit from 6” of
fiberglass above the ceiling. In colder climates, you need 12”. If the home is heated by electricity or a
means more expensive than gas, propane or heating oil, extra insulation usually makes good economic
sense.

The effectiveness of insulation is measured in R-value, which is the resistance of the material to heat
transfer. The higher the rating, the more insulating value. For example, 12” of fiberglass insulation
usually carries an R-38 rating. Six inches of the same fiberglass will be rated at R-19.

Batt and roll blanket insulation is made to fit between joists and studs installed either 16” or 24” on
center. When you see coverage figures for insulation, those numbers include framing area. For example
a roll of insulation described as “covers 80 SF” will fill a wall area measuring 8’ by 10’.

If a vapor barrier is already in place, or if you’re installing a separate vapor barrier, use unfaced rolls or
batts. Otherwise, install Kraft-faced insulation. However, there’s one exception when adding more
insulation in an attic space. Even if the existing ceiling insulation doesn’t have a vapor barrier, install
unfaced insulation.

Loose fill insulation is just as effective as rolls or batts and it’s easy to install in an attic. Simply pour
insulation between the joists and screed it off to the right thickness (Figure 5-1).