R30 Vs. R38 Insulation: Which One Is Better?

In some regions of the United States, home insulation is a very important thing. The quality of the insulation in your home can mean experiencing large heating and cooling bills. Your comfort may also suffer if you have the proper level of insulation. When comparing insulation, many homeowners get confused about R values. What is the difference between R30 and R38 ratings on insulation?

The R-value associated with insulation measures resistance to heat flow through the insulating material. The higher the number associated with the R-value, the greater the insulating value. Insulation with an R-Value of R-38 is about twenty percent more efficient than R-30. R-values are cumulative as you add insulation layers to your home’s attic or walls.

R-value is important when determining how much and what kind of insulation to install in your home. Understanding how your geographic zone affects your insulation project can impact your budget and material choices. There are many options for both materials and installation techniques warranting consideration.

The R-value assigned to insulation measures the thermal resistance of the insulation material. In simpler terms, the R-value expresses the insulation materials’ resistance to transferring heat through the material.

The R-value of most insulating materials is calculated by taking the thickness of the material and dividing it by the thermal conductivity of the insulation. For example, a sheet of insulation that is two inches thick with a thermal conductivity of .25 BTU’s per inch equals an R-value of eight.

2 inches (thickness of the insulation) divided by .25 (thermal conductivitiy equals 8)

Consequently, the sheet of insulation will show R-8 on the labeling. The R-value is an important factor. The R-value on the insulation product is dependent on the thickness of the insulation. If you are installing batt insulation that rolls into place, the batt’s thickness is pre-determined. However, if you are using loose insulation, you must make sure the thickness meets the manufacturer’s specifications to achieve the advertised R-value. Insulation and R-Values

Insulation comes in many different configurations made from different materials.

R-values allow customers a means of comparing these different materials. However, there are some other factors to consider beyond just the R-value. Before you start to add insulation to your home, you should carefully consider these other factors.

Comparing insulation types should go beyond just looking at R-values. The installation requirements are very important as well. In some cases, the needed depth or thickness of the insulation required for your needs may be prohibitive. In other cases, the installation may require specialized equipment or training. Each type of insulation has its unique characteristics to consider.

The location and the type of construction can also impact which insulation is better suited for your project. For example, you may need insulation with an R-value of 38. However, the concrete block construction of your home makes installing many types of insulation impossible. The insulation you install must be appropriate for the location and type of construction.

There is a wide variety of insulation types and materials available. However, some of these materials are not suitable for residential use. Others require specialized tools or equipment, making them better suited to a professional installation. However, many types of insulation materials are installable by a homeowner intent on improving the efficiency of their home. Each type and material has its advantages and disadvantages that you should consider before starting your project.

These types of insulation common use are in unfinished walls, during new construction where stud spaces are still open, and retrofitting attic spaces. The batts or rolls fit between rafters or wall studs sixteen inches on center.

Blankets, rolls, and batts of insulation are probably the easiest types of installation for do-it-yourselfers to install in attics. If the space to be insulated has exposed studs, the insulation material is quick and easy to install.

Rolls and batts usually rate at R-13 or R-15. Most roll and batt insulation has a foil or paper backing that also acts as an infiltration barrier when installed between rafters or studs. A few products offer ratings in the R-19 and R-21 values.

The exterior of unfinished walls and basement walls are the typical application for foam board insulation. In some cases, foam board insulation is applied to walls or ceilings before finish coverings are applied.

Foam board may be used in attics with minimal height under low slope roofs. If applied inside a structure, the foam board must be covered with ½ inch gypsum board. Suitable exterior finishes must be put over foam board.

Foam board insulation R-values vary from 3.6 to 8 depending on the material. One advantage of foam board insulation is its ability to mitigate thermal transfer from other materials such as concrete or steel studs.

Blown-in or loose-fill insulation works best on enclosed or existing structures. Wall cavities can be filled without doing extensive damage to open the wall. The shallowest attics can be effectively insulated by blowing in the insulating material. Usually, the blower equipment rental is relatively cheap where you buy the insulation.

The major problem with blown-in or loose-fill insulation is getting a consistent insulation depth over large areas. The hose can be difficult to control in small spaces. Obstructions in the attic space can create problems getting an even layer of insulation in tight spaces.

Most blown-in and loose-fill insulation have an R-value of 2.2 and 2.7 per inch. To achieve an R-value of 20, you must install at least 8 inches of loos-fill insulation in an attic.

In general, foam insulation must be applied while wall cavities and the underside of the roof are uncovered. Not many homes use foam insulation. Commercial applications, especially in steel buildings, are the most common applications for spray foam insulation.

The R-value of spray foam insulation is between 3.6 per inch to 5.7 per inch. Most applications on stud walls fill the cavity giving you a four-inch depth. A stud filled with medium density foam with an R-value of 5.7 per inch gives you a total R-value of 22.8.

Under some circumstances, simply adding more insulation may not be a better choice. The reality is that at some point, you reach a point of diminishing returns where the cost of the insulation and the installation exceed what you can save on your utility bills.

Several factors work into this equation. No insulation is perfect. There will always be some thermal transfer happening. Spending more to gain a fractional advantage is uneconomical and inefficient.

If you are insulating an attic, the more insulation you add, the greater the weight. The lower parts of the insulation compact, reducing the effectiveness of the insulation.

The goal is to determine the most efficient amount of insulating material for the best cost savings. Using the insulation zone tables and doing some preliminary calculations can help you arrive at the optimal amount of insulation to achieve the best R-value.