adding insulation to an existing home
Unless your home was specially constructed for energy efficiency, you can
usually reduce your energy bills by adding more insulation. Many older homes
have less insulation than homes built today, but adding insulation to a
newer home may also pay for itself within a few years.
To determine whether you should add insulation, you first need to find out
how much insulation you already have in your home and where.
A qualified home energy auditor will include an insulation check as a routine
part of a whole-house energy audit.
An energy audit will also help identify areas of your home that are in need
of air sealing. (Before you insulate,
you should make sure that your home is properly air sealed.)
If you don't want an energy audit, you need to find out the following:
If you live in a newer house, you can probably find out this information
from the builder. If you live in an older house, you'll need to inspect
the insulation yourself if you don't want an energy audit.
- Where your home is, isn't, and/or should be insulated
- What type of insulation you
- The R-value and the thickness or
depth (inches) of the insulation you have.
Inspecting and evaluating your insulation
- Check the attic, walls and floors adjacent to an unheated space, like a garage or basement. The structural
elements are usually exposed in these areas, which makes it easy to
see what type of insulation you have and to measure its depth or thickness
- Inspect the exterior walls using an electrical outlet:
- Turn off the power to the outlet.
- Remove the outlet cover and shine a flashlight into the crack
around the outlet box. You should be able to see if there is insulation
in the wall and possibly how thick it is.
- Pull out a small amount of insulation if needed to help determine
the type of insulation.
- Check outlets on the first and upper floors, if any, and in old
and new parts of a house. Just because you find insulation in one
wall doesn't mean that it's everywhere in the house.
- Inspect and measure the thickness (inches) of any insulation in unfinished
basement ceilings and walls, or above crawl
spaces. If the crawl space isn't ventilated, it may have insulation
in the perimeter wall. If your house is relatively new, it may have
been built with insulation outside the basement or foundation walls. If so, the insulation in these spaces won't be visible. The builder
or the original homeowner might be able to tell you if exterior insulation
- Once you've determined the type of insulation you have in these areas
and its thickness (inches), see the U.S. Department of Energy's online
Insulation Fact Sheet for how to determine
the R-values of insulation previously installed in your home.
Determining recommended R-values
When you find out the R-values of your home insulation from the home builder
or your own inspection, you can then use the U.S. Department of Energy's Zip-Code
Insulation Program to determine how much insulation you should add and
where to achieve the recommended insulation levels for maximum energy efficiency.
Estimating costs and payback
See the page on estimating the
payback period of additional insulation.
what type of insulation to add
If you decide to add insulation to your home, review the information on
the types of insulation available
to help you decide what type to use and where.