What is R-Value?

Insulation is rated by something called Resistance value AKA R-value. R-value is determined by insulations thermal resistance or resistance to heat flow. Insulations R-value is also determined by the materials used, thicknesses and its density. No matter what type of insulation you decide to buy, the R-value determines the how well your insulation is going to insulate your home.

The Label

Depending on what type of insulation you purchase, the R-value must be clearly placed on all residential insulation products. The R-value rules are set up by the Federal Trade Commission in the United States to protect the consumer. The labels state all of the information about the insulation products R-value including information about health, fire and safety issues that may be involved with the installation of this product. Definitely read all of the labels before you purchase any materials.

The R-value

R-values for insulation can be a bit tricky. For example, while the R-value of batt or roll insulation is rated at, let's say R-19, the actual rating of the wall it is installed in will be different. This is because the thermal resistance through the joists or studs between the insulation is not included and therefore changes the entire structures R-value.

Another common misconception about insulations R-value is that more is better. Adding more insulation can increase R-value slightly, but the catch is that R-value is determined by the thickness of the product and its density. For instance, if two layers of batt insulation are added on top of one another in between joists or studs and one layer is compressed by the other, the R-value will increase, but not double. Always install the correct batt thickness required for your particular application; otherwise you could be wasting your time and money.

Conduction, convection and radiation all play an important role in final R-values of your home. Radiant barrier insulation has a low R-value, yet it reflects the majority of thermal radiation into the home. When used in conjunction with loose fill insulation in an attic or crawl space it exponentially increases R-value of the home. On the other hand conductive materials like dark shingles decrease overall R-values of the home by absorbing the heat from the sun and increasing conduction and convection of the roof, lowering R-values exponentially as the suns rays increase throughout the day.

All in all, R-value can be tricky subject to conquer when deciding what insulation is best for your home. Always read the labels and remember that the higher the R-value, the more resistance it has to heat flow.