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Everything you Need to Know About Attic Insulation

attic insulation

Insulating your attic can significantly reduce your utility bill. Without insulation, you can lose up to 45% of your air conditioner’s energy through the roof during the summer. Imagine what that does to your electric bill!

Keeping your home at a comfortable temperature is not the only benefit to come out of having good attic insulation. Moisture and condensation can be a nuisance at best and downright unhealthy at worst. When there’s too much moisture and condensation in your home, dampness and mold are soon to follow. Insulation protects from outside noise as well. That’s just a little added bonus.

How Does it Work?

During summer, the air outside the home is heated up, while the air inside the home is cooled by air conditioning. Without proper attic insulation, the hot air from outside the home gets inside, thus raising the temperature and putting an extra load on the air conditioning system.

Insulation works by trapping air inside of it. This prevents hot air from coming into contact with the air inside the home. The same principle applies in cold regions, where insulation prevents cold air from entering the home.

Blanket Insulation

Blanket insulation, also called batt or roll, are large pieces of insulation made of interweaving fibers with adhesive binders to hold it together. Batts are available as fiberglass, mineral wool, plastic fibers, and natural fibers. Batts insulation is often packaged in rolls of various widths and thickness. Sometimes they come with a vapor barrier that protects against moisture, and they can be installed in multiple layers for added insulation. Batts are best used in attics with standard joist spacing, few obstruction, and attics where you have enough headroom for maneuvering during installation.

Fiberglass is the most common type of blanket insulation. Fiberglass consists of extremely fine glass fibers. R-values (capacity to resist heat flow) for fiberglass batts range from 3 to 4 per inch. Medium and high-density fiberglass have slightly higher R-values than standard batts. The denser products are intended to be used in areas with limited cavity space, like cathedral ceilings. Fiberglass batts can do a poor job of resisting air flow, so it is essential for them to be installed in a sealed cavity. Fiberglass tends to be very irritating to the skin and lungs, so protection is required.

There are two types of mineral wool insulation, rock wool and slag wool. Rock wool is man-made consisting of materials like basalt or diabase. Slag wool is also a man-made material. It is fabricated out of blast furnace slag, which is the scum that forms on the surface of molten metal. Mineral wool contains an average of 75% post industrial recycled content. Because it consists of inorganic materials, it doesn’t require any additional chemicals to make it fire or pest resistant. The R-value of mineral wool is about 3.7 per inch.

Plastic fibers consist mainly of recycled plastic milk bottles. The fibers get formed into batts similar to high-density fiberglass. It is treated with fire retardant. Although it doesn’t burn readily, it melts when exposed to flame. Relatively non-irritating to work with but it can be difficult to handle and cut. Plastic batts may not be readily available in many areas of the U.S. Plastic fiber batts have an R-value of 3.8 to 4.3 per inch.

Cotton and wool are two types of natural fibers used to make batts. They are treated with borate to resist fire, pests, and mold. Cotton is made of about 85% recycled cotton and 15% plastic. Wool can hold large quantities of water but repeated wetting and drying out can leach the borate and decrease its resistance to fire, pest, and mold. Both cotton and wool are non-toxic and don’t require any kind of skin or respiratory protection. The R-value of this material is the same as fiberglass. Unfortunately, natural fiber batts cost about 15%-20% more than fiberglass.

Loose-fill Insulation

Loose-fill insulation is generally made out of small bits of fiberglass, cellulose, and mineral wool. These small particles can conform to any space without disturbing the structure or fixtures. It must be applied using an insulation blowing machine. This type of insulation is best used in attics with irregular joist spacing, attics that have a lot of obstructions that you have to get around, and attics that have existing insulation which needs to be topped off. It is also great for low clearance attics in which you do not have a lot of room to maneuver. Open blow applications are typically used for attic spaces. Closed cavity applications are used for inside walls or covering attic floors. There is generally a settling that occurs with loose-fill insulation.

Loose-fill fiberglass insulation is molten glass spun or blown into fibers. Most manufacturers use 20-30% recycled glass content.

Cellulose is made of recycled paper products, primarily newsprint. The paper is first reduced to small pieces then fiberized. Many manufacturers add mineral borate to ensure fire and insect resistance. Cellulose packs tightly in building cavities and inhibits airflow. It usually requires no moisture barrier and won’t settle in the building cavities when installed at proper densities. The R-value for cellulose is about 3.6 to 3.8.

Spray Foam Insulation

Spray foams are made of two components that are mixed together as they are sprayed. The liquid foam fills all the nooks and crannies. A chemical reaction occurs to make it harden. The most common type of spray foam insulation is polyurethane and can be found as an open cell or closed cell foam.

Open cell foams are permeable to moisture and impermeable to air. This means that open cell foams allow moisture through, but not air. Open cell foams have an R-value of 3.6 which is lower than closed cell foams so you may need a thicker layer.

Closed cell foams are more expensive but have a higher R-value (6.5). They stop air and moisture from penetrating. It can also add strength to the structure it is applied to due to its thick, glue-like gripping quality.

Is Insulating Your Attic a DIY Project?

It depends on the type of insulator you use, but the short answer is yes. The two types of attic insulation available for DIY are loose-fill insulation and batts insulation.

Further attic insulation can be done with attic tents which insulate the attic drop-down stairs and slice your energy bill by about $145 annually. You also have radiant barriers, which can result in a further 8-12% reduction in your annual air conditioning expenses.

Are You Ready to Start?

Talking to a professional contractor is a good idea, even if you intend to make it a DIY project. A professional can perform an audit to determine the exact amount of attic insulation that you need, and determine whether you need to remove any of the previous insulation or material in your attic, or if there are any leaks that need to be fixed.

You also want to check whether your project is up for rebates and tax credits. 

Investing in attic insulation is a great way to decrease your energy bill and create a much more comfortable living space. Contact us today if you’d like to know more.

 

Sources:

https://energy.gov/energysaver/insulation-materials

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