What is R-Value?
What is all this lingo these contractors use? I get asked this all the time from homeowners. A lot of contractors will not speak in layman’s terms to customers. They use terms like linear foot, kneewall, gables, baffles, and R-value; among many others. Most of your average homeowners may not know what some of these terms mean. Let me try to clear up one of the most “unexplained” terms in the industry: R-value.
R-value is the resistance of heat transfer. The higher the resistance value, R-value, the better the insulation. While talking about this, let’s all picture fiberglass batt insulation in our heads, in layman’s terms, the pink stuff. Many people are under the impression that the fiberglass is the actual insulator. This is not true. See, the spun fiberglass is held together with just a tad bit of glue and because of the way that the spun fiberglass sticks together, it leaves air pockets in between each strand of fiberglass. This air is our insulator. Remember, the higher the R-value, the better the insulator. Which means the more air pockets in the insulation, the higher the R-value. For example an R-30 is a better insulator than an R-13. Because an R-30 has more air pockets, it also has more fiberglass, this makes the insulation much thicker.
Then why not put R-30 or R-50, or R-200 in everything? Answer: Because of limited space.
Insulation, especially fiberglass and cellulose (recycled newspaper) only holds it’s R-value in it’s manufactured state. If you cram R-30 into a regular studded wall, you’ll have to mash it down. When you mash it down, you close the air pockets and in turn, you ruin it’s R-value. The less air, the less R-value. This is why it is very important to never compress insulation in walls or around / under wiring. If the insulation is not cut to the proper allotted space, you could be losing R-value, which is wasting energy. Attics are usually a different story. If you only have R-19 in your attic, adding an R-30 to the already insulated space is usually pretty easy. This will give you an R-49, which is what Energy Star recommends for our region. It will save a lot of energy and lower your bills each month.
To find out your home’s R-value, call us at 443-459-5800. Cameron Building Envelope Specialists will measure your insulation and use tools of the trade to determine whether your home is under insulated.