Let’s discuss why we need insulation before we answer the question “how much attic insulation do I need in my home?” According to the US Department of Energy, heating and cooling accounts for 50% to 70% of the energy used in the average American home. That 20% spread is a huge difference. Insulation is the key factor in getting those numbers lower. It is one of the most efficient ways to save energy at home since it keeps the home warm in the winter and cool in the summer.
Inadequate insulation and air leakage are leading causes of energy waste in most homes. Conversely, adequate insulation makes your house feel more comfortable. It does that by helping to maintain uniform temperature throughout. In addition, an adequate amount of insulation saves more money and natural resources. Adequate insulation also helps to control moisture. And we are constantly reminded that controlling moisture is essential to reduce the chance of evil fungal growth.
How Much Energy Can I Save by Improving Attic Insulation?
If you have decided to improve your attic insulation in an existing house, I applaud you. Energy recommendations and building codes related to energy evolve constantly. Unless your home was constructed to a higher standard than was required at the time of construction you could probably significantly save energy and money by improving attic insulation.
How much energy you can save by installing insulation depends on several factors. Those include your local climate, the size, shape, and type of construction of your house, as well as your family’s living habits and the efficiency of your heating and cooling system. The type of fuel you use to acclimatize your home can also have an impact on energy consumption.
According to an EPA study, homeowners in our area can save an average of 9% on heating and cooling costs. An average of 6% can be saved on total energy costs. All that by air sealing their homes and adding insulation. Possible locations might include attics, floors over crawl spaces, and accessible basement rim joists. This estimate is based on energy modeling of cost-effective improvements made to ’typical’ existing U.S. homes.
How Much Attic Insulation Should I Add
When installing additional insulation in your home you will want the highest R-value in the attic and cathedral ceilings. Walls have less thermal load. That’s why solar panels work better on roofs. Let’s look at a home in zone two, which is our area of southeast Texas. And narrow it down to a ZIP Code beginning with 770, which is the general Houston area. At the time of the study this “average house” had a natural gas heating system and an electric cooling system. In that case, R-38 was recommended in attics and cathedral ceilings, R-13 in floors and R-15 in wall cavities.
The most common area to add insulation in an older home is in the attic. Before you know how much insulation you should add, you will need to determine how much is already installed. This information lies in the type of insulation. The most common types of insulation found in our area are Loose Fibers and Batts.
Batt insulation is almost always composed of fiberglass materials. They are lightweight and come in several colors including yellow, pink, and white. So, you just need to measure what’s already there. You can estimate an R-value of about 3.2 for each inch of thickness.
There are two common types of loose (blown-in) fiber insulation. Loose fiber insulation that is lightweight having a color of yellow, pink, or white is most often fiberglass. It will have an R-value of about 2.5 for each inch of thickness. Loose fiber insulation that is composed of small gray flat pieces of fibers is made from recycled newspaper. Because of its density you can expect an R-value to be about 3.7 for each inch of thickness.
New Home Attic Insulation Requirements
New home insulation requirements are mandated by the International Energy Conservation Code (IECC). That includes attic insulation and all other required areas. Be aware that many municipalities have yet to adopt any code. And enforcement of any building code outside of a municipal jurisdiction is as rare as hen’s teeth. Good luck when buying a house in those areas without a strong understanding with the builder prior to construction. Back that understanding up with a solid contract.
If you are purchasing a new home where the IECC has been adopted, your builder is required to meet the minimum standards for insulation. You might want to consider having The Wildcat Inspections Team perform a New Home Inspection.
If you are shopping insulation for a DIY project, you should insist on the most current requirements as set out by the Federal Trade Commission (FTC). FTC enforces the R-value rule, which ensures that you get accurate, honest information about the R-value of your insulation before you buy it, have installed, or buy a new home. Manufacturers must label their packages of insulation; installers and retailers must provide fact sheets; and new home sellers must include this information in Sales contracts.
Air Sealing Your Attic
You should know that regardless of the type of attic insulation that you choose it only limits air movement, and only in the space that the insulation occupies. Those limitations should not be confused with “air sealing” the attic. Air sealing is the restriction of air movement from all sources. Seal air leaks throughout the house. Focusing on leaks to the attic space, through the foundation, and around windows and doors. The goal is to achieve a 25% reduction in total air infiltration.
Air sealing in the attic is generally a challenging DIY project, but the benefits can be substantial. However, the EPA warns that sealing and older home may trap indoor air pollutants and create unsafe conditions. Those include carbon monoxide, radon and volatile organic compounds (VOCs). Addressing this properly may require additional effort. For instance, ventilation fans might be needed to maintain safe air quality in the home. Also, there might be repairs to reduce or eliminate the sources of indoor air pollutants.
