If You Want a Warm House in Winter, You Really Need to Read This...

Nobody wants to spend winter shivering under a blanket, but simply cranking up the heating isn't always the best solution. Without the right insulation, a large amount of heat can escape from your home, making your heating system less efficient and causing hikes in your energy bills.

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Before you run to the DIY store to purchase rolls of insulation, it's essential to understand what R-values are and how they work. R-values may sound technical, but knowing which rating to choose can make your home more efficient and put an end to chilly winters.

The term R-value refers to how well a material stops heat from entering and leaving your home per inch of thickness. The higher the R-value, the more effectively it prevents heat transfer. In the summer, heat transfers inside your house when the air outside is hotter than your home's interior. The opposite happens in winter when warm air escapes into the colder outdoor environment.

Various factors can affect insulation R-value, including the material, density and installation method. Blown-in, batt and roll and loose-fill insulation typically have lower R-values because they can't fill the tiny gaps that cause air leakage. Meanwhile, expanding spray foam insulation and foam board insulation seal your home more effectively and have higher R-values. You can also combine several insulation types depending on the space you need to insulate.

Why Do You Need Different R-Values for Different Locations?

You'll usually need a higher R-value for insulation in attics and exterior walls. That's because your home is more prone to energy loss in these areas, as small gaps and cracks allow air to flow in and out of your house. The easiest way to achieve a high insulation R-value in exterior walls is by installing foam board insulation between the studs and filling any gaps with expanding foam insulation, including around windows and doors.

Meanwhile, you can increase the R-value of your attic insulation by adding multiple layers. For example, you could consider adding blown-in insulation over pre-installed batt insulation.

Floors and interior walls are less vulnerable to heat loss, and many homeowners choose not to insulate these areas. However, it could be worth installing insulation if you live in an old house or cold climate.

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What Is the Most Common Insulation R-Value?

The most common insulation R-values for attics are R30 through R60. Values for areas like floors and ceilings vary widely depending on the local climate, the home's construction type and whether it has preexisting insulation.

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How Do I Know What Insulation R-Value I Need?

Your local climate is the main deciding factor in what R-value you need. For example, you'd need a significantly higher R-value if you live in a cold region such as Southeast Fairbanks in Alaska than you would in a hot climate like Miami, Florida.

Whether you have preexisting insulation can also make a difference. Generally, you'll need a higher R-value when installing insulation in an uninsulated space than you would when adding an additional layer to existing insulation.

The Department of Energy issues guidelines outlining what insulation R-values you need in different climates. It splits the USA into eight climate zones, each with its own insulation recommendations for different areas of the house. These areas include uninsulated attics, pre-insulated attics, wood-frame walls and floors. Whether you live in a marine climate can also affect what insulation R-value you need, particularly for floor insulation.

The DoE guidance also specifies the type of insulation required in certain areas. It recommends using continuous insulation in insulated wood frame walls in zones three through eight and in uninsulated wood-frame walls in every zone. Continuous insulation is a type of insulation applied inside the cladding of exterior walls.

The easiest way to estimate what insulation R-value you need is to consult the DoE insulation R-value chart. However, your home's construction and the type of heating and cooling system you have may mean you need a higher or lower R-value than the chart recommends. Consulting a professional insulation company can help you determine the best R-value and insulation material for your needs.