Insulating your attic is an excellent way to protect your home from temperature extremes and moisture damage. Insulating also is an effective way to reduce heating and cooling costs. Insulation acts as a barrier to prevent the transfer of heat from the inside to the outside of the house in winter or from the outside to the inside in summer.
An experienced DIYer can install most types of insulation, but if you aren’t sure how to complete the task, consider hiring a professional. Gaps in insulation can quickly reduce its effectiveness. This guide explores the different types of insulation, factors and tips to consider when shopping for insulation, and some of the best types of attic insulation on the market.
- BEST OVERALL: Owens Corning R-38 Kraft Faced Fiberglass Insulation
- BEST BANG FOR THE BUCK: Frost King CF1 “No Itch” Natural Cotton Insulation
- BEST BLANKET: Owens Corning R-30 EcoTouch Fiberglass Insulation
- BEST SPRAY FOAM: FROTH-PAK 620 Sealant – 2 Component Foam Insulation
- BEST RADIANT FOIL: US Energy Products Double Bubble Foil Insulation
- BEST FOAM BOARD: Owens Corning Pink Insulation Foam 1/2″ Thick
Before You Buy Attic Insulation
In most circumstances, it makes sense to add attic insulation. However, in a few situations, installing insulation can cause serious problems, such as in older homes that were built with large gaps between the walls to account for the moisture that naturally leaks into homes. The gaps allowed the moisture to dry without causing damage to the structure, but if these spaces are filled with insulation, it can absorb the moisture and lead to mold and rotted wood.
If you have an old or wood-shingled roof and you attempt to install insulation on the ceiling of your attic, a similar situation can occur. These older roofing materials were made to get wet, breathe, and dry, but with insulation blocking the wood, the moisture will only accumulate. Also avoid using insulation anywhere near knob and tube wiring, which is an outdated electrical system that’s a major fire risk and should be replaced as soon as possible.
Types of Attic Insulations
Attic insulation is available in several different types, including blanket, spray foam, radiant foil, and foam boards, each with benefits and shortcomings.
Blanket insulation is one of the most common types of insulation for walls and attic floors; however, don’t use it in open spaces because the fiberglass particles can affect the air quality in your home. Cut the thick pieces of insulation to fit tightly between the gaps in wooden frames or around pipes, wires, and other obstacles.
While this insulation is also one of the most inexpensive and easiest types to install, it isn’t as effective as spray foam insulation. When installing blanket insulation, wear a breathing mask and protective gloves so it can’t irritate your lungs and skin.
Spray foam insulation is the primary type of attic insulation. Pair it with blanket insulation to better insulate edges and corners, and use it to seal gaps in existing walls. The most expensive type, it can be a hassle to remove; however, it’s the most effective option for insulating your home against the transmission of hot and cold air.
The spray foam is made of liquid polyurethane, which, when sprayed into the cavity of your wall or attic, expands and hardens into a solid foam. If you haven’t used spray foam before, consider hiring a professional to install it to ensure your home is adequately protected.
Because it’s designed primarily to reflect heat away from your home, radiant foil insulation is more common in warmer climates. It works through its reflective foil barrier, which is attached to kraft paper or polyethylene bubbles. The bubbles help prevent the transfer of heat through the barrier because they provide a pocket of air, which reduces the rate that heat can move through the substance.
While standard insulation reduces the flow of heat, radiant foil reflects it. Because of this difference, radiant foil cannot be measured using the same factors attributed to blanket, spray, or foam board insulation. Radiant foil usually is the most affordable type of insulation.
Low in cost and easy to install, foam board insulation is generally made of polyurethane, polystyrene, or polyisocyanurate. Sheets of foam board can be cut to fit tightly between wall studs or attic ceiling joists. Because they are not as effective at insulating, foam boards are not as popular as blanket insulation.
However, foam boards don’t cause moisture accumulation and mold growth as can blanket insulation, because the solid foam doesn’t absorb a lot of moisture. Instead, it dries in a relatively quick time frame.
What to Look for When Buying the Best Attic Insulation
Finding attic insulation for your home isn’t difficult once you’ve determined which type of insulation to purchase. However, there are other factors to consider, including the R-value and material.
Attic insulation ranges in effectiveness, so to help people find the best attic insulation for their homes, manufacturers and industry professionals typically reference insulation’s R-value. R-value is a measurement of insulation’s resistance to the flow of heat. The higher the R-value rating of a product, the more effective it is at reducing energy costs in your home.
R-value is usually listed in the product description or on the product packaging. However, radiant foil insulation isn’t measured by R-value because it’s designed to reflect heat instead of reducing the transmission of heat. The optimal R-value for the insulation in your home also depends on your geographic location. Review this Energy Star R-value chart to learn the estimated R-value for your geographic region.
Attic insulation can be constructed from a wide range of materials, including cellulose, fiberglass, mineral wool, liquid polyurethane, and polystyrene.
- Cellulose was used regularly in building insulation for most of the last 100 years. It consists of cellulosic materials like newspaper, cardboard, cotton, straw, hemp, and sawdust. At just 3.8 per inch of cellulose insulation, the R-value is relatively low.
- Fiberglass insulation is made from tightly woven fibers that are light, malleable, and relatively simple to cut and install. This material is regularly used in blanket insulation and has an R-value of 2.7 per inch.
- Mineral wool has an R-value of 3.3 per inch. It’s a stone-based mineral fiber insulation that contains basalt rock and recycled steel slag.
- Liquid polyurethane is the main ingredient in spray foam insulation. The R-value of this type of insulation ranges from 3.5 per inch to 6.5 per inch, depending on whether you’re using open-cell (3.5) or closed-cell (6.5) spray foam.
- Polystyrene is used to create foam board insulation with a variable R-value of 3.8 per inch to 5 per inch, depending on whether it’s expanded polystyrene (styrofoam) or extruded polystyrene, which can be identified by the blue or pink color.
Tips for Buying and Using Attic Insulation
Keep in mind that insulation cannot be installed just anywhere in your home. For instance, if blanket insulation is placed over air intake vents, the harmful particles can circulate through your home. Additionally, placing insulation near exposed electrical connections or over the top of heat vents could cause a fire.
Based on the type and style of the home, also consider how and where to place the insulation. Older homes and homes with wooden shingles may be built with a design that allows the natural evaporation of excess moisture. Insulation installed in these areas acts as a sponge, soaking up the moisture instead of allowing it to dissipate. As moisture builds up, mold can grow and eventually rot out the wood.
With blanket insulation, cut spaces in the insulation to allow it to fit around obstructions like drainage pipes, large water pipes, and HVAC ducts. When blanket insulation becomes compressed, it’s less effective at insulating your home, such as when you forcibly install a piece of insulation around a pipe instead of cutting a gap to allow it to fit comfortably.
- Don’t install insulation over air vents, near electrical circuits, or in any other areas where it poses a risk.
- Carefully inspect older homes before installing insulation to ensure it won’t cause moisture accumulation that can lead to mold and rot.
- Blanket insulation is not as effective if it’s compacted during installation, so cut spaces for large drainage pipes and other obstacles instead of forcing the insulation to fit around them.
Our Top Picks
The top-rated products below were chosen for their quality, price, and customer satisfaction to help you find the best attic insulation to protect your home from high- and low-temperature extremes.
Install this insulation from Owens Corning in an uninsulated attic or add it as a second layer to increase the R-value potential of a home and cut heating and cooling costs. The insulation is made of 35 percent recycled content, and it’s designed to be non-absorbent. As a result, it can resist moisture absorption even in areas that experience higher humidity.
This package includes eight pieces of fiberglass attic insulation, and each piece measures 4 feet by 2 feet. Using all eight pieces without cutting them covers a 64-square-foot space with 8.25-inch thick insulation. This blanket-style attic insulation is easy to cut and install, and the thick insulating material also helps reduce noise and vibration in your home.
Affordable and effective, this natural cotton attic insulation by Frost King is 1 inch thick and measures 16 inches by 48 inches. Use one or more pieces of this insulation on attic walls, ceiling, and floors, or cut or rip up smaller pieces of insulation to fill in gaps around pipes, ducts, windows, and doors.
Made with cotton denim that’s resistant to mold, mildew, and fire insulation, this is an all-natural alternative to woven fiberglass. Moreover, natural cotton denim is safe and easy to install with just your hands and a utility knife.
This blanket insulation from Owens Corning is easy to cut, position, and install in just about any space. The woven fiberglass insulation is made with more than 99 percent natural ingredients, including minerals, plant-based compounds, and 65 percent recycled content.
This blanket insulation comes in a 9-inch-thick roll. It boasts an R-value of 30, keeping your home warm in colder months and cooler in the warmer months. The insulation aids in reducing the transmission of noise.
This closed-cell polyurethane spray foam attic insulation by FROTH-PAK has an approximate R-value of 6.5 per inch, and the kit includes 51.7 cubic feet of spray foam, which is enough to spray approximately 620 square feet of foam at a 1-inch thickness.
The spray foam attic insulation kit includes a 15-foot hose, a spray gun dispenser, 16 cone nozzles, and eight fan nozzles that offer precision, no matter the application. Once the foam is sprayed, it will expand, solidify, and fully cure in under one minute.
This radiant foil attic insulation by US Energy Products is a solid option when paired with another insulating material like foam board or blanket insulation, because radiant foil can reflect up to 97 percent of radiant heat. The secondary insulator resists the flow of the residual heat. This insulation is easy to cut with a utility knife or scissors and simple to install with staples, nails, or an adhesive.
The insulation acts as a sandwich with two layers of reflective metalized aluminum polyester film on the outside and two layers of polyethylene air bubbles on the inside. The air bubbles reduce the flow of heat, while the foil reflects the radiant heat. This construction keeps homes cool in warmer climates and warm in colder weather.
Foam board insulation is rigid and lightweight, making it easy to carry and install on floors, walls, ceilings, and around windows. Use a warm utility knife to slice through this foam board from Owens Corning with a high degree of precision. This method allows users to form the insulation to the exact size requirements or even to cut rounded shapes in the foam board so heat isn’t lost around pipes or other obstructions.
The package includes seven foam boards with an R-rating of 3.0. This insulation is moisture-resistant and ideal for sealing narrow gaps around windows and doors where significant amounts of heat can be lost from a home in the winter months.
FAQs About Attic Insulation
Before investing in new attic insulation, take a look at these frequently asked questions and their answers.
Q: What is the best R-value for attic insulation?
The best R-value depends on the typical temperature fluctuations in your city or state, but average R-value recommendations for attic spaces range between R-30 to R-49.
Q: Which type of insulation is the most effective?
Spray foam insulation is the most effective type, with a maximum R-value of 6.5 per inch.
Q: Can you put too much insulation in the attic?
Yes, you can. If this occurs, moisture can become trapped inside the space, causing mold and air quality problems.
Q: Should you remove the old attic insulation before adding new insulation?
You can remove the old attic insulation before adding new insulation, but it isn’t necessary unless the old insulation is wet, made with hazardous materials (like asbestos), or simply degrading too quickly to serve any remaining purpose.