The attic level of a building can permit cool drafts into the building during colder months and heat in during the summer months, which not only makes the building uncomfortable but can also increase the energy bill. However, insulating attic spaces and attic door insulation provides comfort in every season as well as a quieter space to live and work and can even help lower energy bills.
The Different Types of Attic Insulation
Attic insulation varies in type from foam spray to fiberglass batts and even recycled newspaper; however, they all perform the same duty and that is to retain small pockets of air that retard the flow of heat into and out of a building.
Insulation is rated by its R-value, or its ability to resist the movement of heat into and out of a building. The greater the R-value, the smaller the energy bill will be.
There are two basic methods for installing insulation in the attic: spray insulation and batt insulation. Some common forms of attic insulation as well as how to insulate an attic include:
Installing Unfaced Batt Fiberglass Insulation
There are two types of fiberglass batts: faced and unfaced. Usually, experts recommend using unfaced fiberglass batts as opposed to faced fiberglass batts because they contain a paper or foil layer, which can trap moisture in the ceiling.
To install unfaced fiberglass batts, position the batts across the ceiling joists, on top of the previously installed insulation. As you continue to lay the batts, be sure they are pressed snugly together at all end joints and edges. Once you reach the outside of the attic, position the insulation up to the roof rafters but away from plywood roof sheathing.
Be advised that fiberglass batts need to be installed properly, or snugly fitted to all sides of the framing cavity, in order to achieve its true R-value. Note that it is important to wear gloves, a long sleeve shirt, eye protection, and a dust mask when installing attic insulation in order to avoid skin and lung irritation.
Installing Faced Batt Fiberglass Insulation
Faced batt attic insulation is a good option for attics that have never been insulated. It is installed similarly to unfaced batt insulation, except you staple as you go.
Begin the insulation in one corner, pushing the batt securely into the cavity, face side down, and be sure to cover the top plate. Staple at least every eight inches. Continue to lay the batts, pushing them tightly against each other so that there are no gaps.
As with unfaced insulation, be careful not to cover roof or socket vents. In fact, you should use rigid foam or cardboard baffles to cover vents. In addition, avoid placing faced batt insulation more than 3 inches away from hot areas, such as recessed lighting fixtures, to prevent overheating.
Installing Cotton Batt Insulation
Cotton batts are comprised of recycled denim acquired from jean factories, and they are fire and insect resistant. Install cotton batts similar to other unfaced insulation batts, and as always, remember to wear a face mask and plastic gloves when installing insulation to prevent lung and skin problems.
Installing Foam Spray Insulation
Spray foam is the most recommended form of insulation because of its ability to expand and fill all gaps and hard to fill areas such as spaces with air handler ducts, intricate framing details, and behind light fixtures and electrical sockets etc.
Using a 2-part low-density polyurethane foam spray, which can be purchased online or from an insulator contractor, and a fan width nozzle, spray each dry, clean wall or ceiling cavity approximately 1 1/2 to 2 inches deep in an up and down motion until the cavity is filled and there are no gaps. Continue this process until the entire attic is insulated.
Cover electrical sockets securely with plastic in order to prevent the spray from entering the sockets. Also note, it is important to wear a respirator mask and plastic gloves when installing spray foam insulation in order to avoid lung and skin issues.
Installing Cellulose Insulation
Cellulose insulation, which is milled recycled newspaper that is treated with boron to resist fire and pests, is another type of insulation that is sprayed or blown into wall or ceiling cavities to provide insulation.
The process of installing cellulose installation is similar to the spray foam process with the exception that it is blown harder into cavities using a specialized blower. Once the insulation is dry, typically within a day, it is then shimmed back to the studs with a stud scrubber for even coverage.
As with any insulation process, be sure to wear a face mask and plastic gloves to prevent skin and lung irritation.
The Benefits of Installing Attic Insulation
The attic undergoes great temperature extremes, which can significantly affect the overall temperature of the building; therefore, the main benefit of installing attic insulation is that it keeps the building comfortable all year round, which can also help lower the energy bill. In addition, insulation also provides a more peaceful space for living and working.
The Cost of Installing Attic Insulation for Large Projects
Attic insulation cost varies depending on the materials; however, those with a greater R-value, such as foam insulation, can be a bit more expensive, which experts suggest is worth the price.
According to reports, on average, cotton batts with a 3.7 per inch R-Value, cost anywhere from 70 to 75 cents per square foot, while fiberglass batts with a 3 to 4 per inch R-Value typically runs about 38 cents per square foot.
Low-density polyurethane spray foam with a 4-inch R-Value can run 4 times higher than the cost of fiberglass batts, or about $1.42 per square foot, while cellulose insulation with a 3.8-inch R-Value typically costs about 17 cents per square inch.
Other insulation choices include loose-fill fiberglass, which costs 21 cents per square foot on average, and mineral wool, which costs about 19 cents per square foot.
In the end, the best attic insulation for your building will depend greatly on your local building codes and regulations, which will determine the R-Value and insulation type applicable to your specific building.