Home Insulation: Getting Your (R) Value

Home Insulation: Getting Your (R) Value
Polyurethane spray foam could be the right choice for keeping heat out and reducing energy costs. (Source: Georgia Foam Solutions)
Polyurethane spray foam could be the right choice for keeping heat out and reducing energy costs. (Source: Georgia Foam Solutions)

Homes and buildings need insulation to control inside temperatures. Are you getting the best value for your project? Here's a look at how R-Value affects what you pick.

What is R-Value?

R-Value, also known as "thermal resistance," is a measurement of how much resistance a material has to heat flow. Or in other words, how well does it block heat?

For insulation, this is an important factor. Most states have requirements for the R-Value of any new building projects, like residential and commercial buildings. The R-value for these large projects is often based on an overall calculation of the R-values in specific areas of the building, such as the roof. Single materials, however, also have an R-value rating that should be paid attention to.

The higher the R-Value, the better the thermal performance of the insulation. In South Georgia, Energy.gov recommends insulation with an R-Value of 30-60 for attics, 22-38 for cathedral ceilings, 13-15 for cavity (room walls), and 13 for floor insulation.

Thoughts for consumers

R-Value is an important factor when choosing insulation materials. But it certainly should not be the only one. The ease of installation, longevity, and strength of the product should also come into play when choosing which material is best for you.

Moisture resistance and airflow should also be considered, as they can be major factors in potential problems later on.

For example, closed cell polyurethane spray foam has excellent moisture and weather resistance and is extremely resistant to airflow, while fiberglass insulation can accumulate moisture and much more is needed to dampen airflow.

What is the R-Value myth?

To the average person, the higher the R-Value of your insulation, the warmer you should feel in the winter and cooler in the summer. But the reality is much different as the R-Value listed on insulation is not arrived at under real-world conditions, making them extremely misleading to the consumer.

For instance, fiberglass is generally assigned an R-value of approximately 3.5. It will only achieve that R-value if tested in an absolute zero wind and a zero moisture environment. Zero wind and zero moisture are not real-world. The average home with all its doors and windows closed has a combination of air leaks equal to the size of an open door, hence the reason why so many people feel that their homes are drafty.

So, even if you did a perfect job of installing Fiberglass or Cellulose insulation in your home and brought the air infiltration close to zero from one side of the wall to the other, you would still not stop air from moving vertically through fiber-based insulation itself in ceilings and walls.

Water vapor from the atmosphere, showers, cooking, and even breathing constantly moves back and forth through walls and ceilings, dropping Fiberglass or Cellulose insulation's R-value - as much as 50 percent.

By some estimates, 50-60% of your heat escapes through light fixtures, vents, and directly through your ceiling into the attic and out from there through places like ridge vents. This is why when considering insulation, addressing deficiencies in the attic can give you the biggest bang for your insulation dollar.

The only way to stop the moving of air and moisture within a building's structure is by using an air and vapor barrier. One inch of spray Polyurethane foam insulation properly installed throughout the building structure can prevent more heat loss than all the fiber insulation that can be crammed into the structure's walls.

Georgia Foam Solutions

Georgia Foam Solutions provides fiberglass and foam installation services to help keep your home insulated and keep your energy costs low.

Learn more about the benefits of polyurethane foam insulation from Georgia Foam Solutions at www.gafoamsolutions.com.

Featured image courtesy of Flickr via Red Moon Sanctuary