Insulate Today. Save Tomorrow.
About NAIMA  |  Contact Us

About Insulation Categories

Did you know...
About Insulation > Application-Specific Information > Residential Home Insulation
Print this FAQ

Where to Add Insulation to an Existing Home

To achieve the maximum thermal efficiency and comfort, it is important to insulateTo cover with a material of low conductivity in order to reduce the passage or leakage of heat, reduce the surface temperature, or reduce the noise emanating from the object. any space were energy could be lost. For optimum energy savings and comfort, consider adding additional insulation to your home.Where to Add Insulation in Your Home

1. Attics and Ceilings

Fiber glassA material consisting of glass fibers used in making various products, including yarns, fabrics, insulation, and structural objects or parts. Fiber glass is resistant to heat and fire., rock woolA synthetic vitreous fiber insulation made by melting predominantly igneous rock and other inorganic materials, and then physically forming them melt into fibers. See Mineral Wool., and slag woolMan-made material made primarily from iron ore blast furnace slag. insulation in attics and flat ceilingsA ceiling with no change in elevation. makes the home more resistant to energy loss and lowers energy bills. To achieve R-valuesMeasure of resistance to heat flow. Insulation materials have tiny pockets of trapped air. These pockets resist the transfer of heat through material. The ability of insulation to slow the transfer of heat is measured in R-values. The higher the R-value, the better the insulation material's ability to resist the flow of heat through it. The Federal Trade Commission prohibits expressing R-value in terms of inches, because R-value is not a linear measurement. R-values can be added togehter for a total system R-value. of R-38 and higher, two layers of insulation battsPre-cut pieces of insulation in standard sizes; batts may have a facing of kraft paper, aluminum foil or poly (plastic) or no facing at all. and/or rolls can be used and their R-value added together. For example, an R-19 batt or roll added to an R-30 batt or roll will yield an R-value of R-49. When installing a second layer, always use unfaced insulationInsulation with no attached vapor retarder or facing.. Also, it is recommended that the second layer be applied across the joistsHorizontal framing member set from wall to wall to support the floor or ceiling. and all batts be installed so there are no gaps between them. Fiber glass, rock wool, or slag wool  loose-fill insulationInsulation in granular, nodular, fibrous, powdery or similar form designed to be installed by pouring, blowing or hand placement. can also be used.

2. Walls

Sections sometimes overlooked in homes are walls between living spaces and unheated garages or storage rooms, dormer walls, and the portions of walls above ceilings of adjacent lower sections of split-level homes. Today’s fiber glass, rock wool, and slag wool insulationMan-made material made primarily from iron ore blast furnace slag which is spun into a fibrous form. products are manufactured to fit in both 2 x 4 and 2 x 6 construction.

3. Floors

Areas that are often not insulated are floors over unheated or open spaces such as garages or porches, floors over unheated basements, and the cantilevered portions of floors. Insulation batts can be used in these areas. When insulating floors over unheated basements or crawl spaces, faced products should be used and vapor retarders should face heated areas and be in contact with the subfloorThe structural material that spans across floor joists. It serves as a working platform during construction and provides a base for the finish floor..

4. Basements

For finished basements, R-13 batts can be used. (Verify that the walls are dryTo change the physical state of a substance by the loss of solvent constituents by evaporation, absorption, oxidation or a combination of these factors. and do not leak ground moisture before insulating a basement.) Vapor retarders should face heated areas and be covered as soon as possible. Do not leave combustibleCapable of catching fire or bursting into flames. facings exposed. For insulating foundation walls of heated crawl spaces, use either unfaced insulation where the building code does not require a vapor retarderHelps control the amount of moisture passing through the insulation and collecting inside exterior walls, ceilings and floors. It is rated in perms ("permeance"). The lower the perm rating, the better the water vapor permeance. A vapor retarder should have a perm rating no greater than 1.0. or insulation with a special facingDefinition One: A thin layer of laminate, usually factory applied, on the surface of an insulating material. Definition Two: A protective or decorative (or both) surface applied as the outermost layers of insulation. recommended for exposed applications. The insulation should be fastened to the sill plate and draped down the wall.

If you are considering installing additional insulation in your home, see this page for "How To Install Insulation" information.

To learn more, see the following NAIMA Publications:

Where to Insulate in a Home
Reasons to Insulate Your Home

Subscribe to latest FAQs
About NAIMANorth American Insulation Manufacturers Association, a trade organization representing manufacturers of fiber glass and rock and slag wool insulation products in North America.
NAIMA is the association for North American manufacturers of fiber glassA material consisting of glass fibers used in making various products, including yarns, fabrics, insulation, and structural objects or parts. Fiber glass is resistant to heat and fire., rock woolA synthetic vitreous fiber insulation made by melting predominantly igneous rock and other inorganic materials, and then physically forming them melt into fibers. See Mineral Wool., and slag woolMan-made material made primarily from iron ore blast furnace slag. insulation products. The NAIMA "About Insulation" section contains a wealth of information and guidance on many insulation products and their application in the residentialPertaining to a home or homes where people reside on a permanent basis., commercialA building classification - related to business as in commercial building., mechanical and industrial insulation industry as well as specification, codes and standards, and related industry issues such as energy-efficient construction of today's homes and buildings. If you do not find what you are looking for, please contact us.