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What Is The Best Type Of Insulation For An Attic?

types of attic insulation

Good attic insulation helps keep your home cool in the summer and warm in the winter. Effective insulation at peak performance will help save you money on your heating and cooling bills.

With all the insulation options, which one is the best option for your home? There are three main types of insulation: blanket insulation, loose-fill insulation, and spray foam insulation. Within each insulation type, there are different materials to choose from.

Blanket insulation is the cheapest option and an easy DIY product for any homeowner. The blanket insulation comes in sheets and is simply placed on the attic floor or section that needs to be insulated.

Loose-Fill insulation can also be a DIY option and simply sits in the area that needs insulation.

Spray foam is the most expensive option with the highest thermal rating. Spray foam requires a machine and a specialist to install.

We will cover each type of insulation in more detail and outline the pros and cons of the different options below while covering the thermal requirements suggested for each option. While every option will work to insulate your attic, the benefits and drawbacks will help decide if you want a long-term high-cost solution or a low-cost option that will work for you.

Insulation R-Value

Each type of insulation material is rated by an R-value. The R-value is the thermal regulation value given to each product to rate its ability to hold in heat. Typically exterior walls have an R-value between 13 – 23 depending on the product and price point, while ceilings and attics have a higher recommendation of 30 – 49 R-value.

Heat rises, and an attic is an easy place to lose heat from in your home. These recommendations are developed by the Department of Energy (DOE) and can change based on your local area. It is best to check the recommendations for your area before picking a product. Warmer areas like Florida and Hawaii require lower insulation ratings as the home does not need to be kept as warm.

You can also think of the R-value is a calculation that measures the “thermal resistance per unit area.” The measurement tells you how well the barrier you have chosen keeps heat in per unit of length.

Insulation R-Value Chart

insulation r value chart for attics walls floors and crawlspaces

Insulation Types

Blanket insulation

pink fiberglass blanket insulation

Blanket insulation is a low-cost insulation option. There are two types of blanket insulation batts: pre-cut industry-standard rectangles and rolls that come in large rolls that can be custom cut to any size.

Blanket insulation is well known as a cost-effective DIY product that any homeowner can purchase and install. It is still important to talk to a product specialist to ensure your attic has proper air ventilation to ensure the insulation does not get moldy and works at peak performance. It is also important to ensure the blanket insulation is rated high enough for your attic. This type of insulation, while easy to install, still needs to be installed tight to the floor to work at its best.

You can purchase blanket insulation in fiberglass, mineral wool, plastic fibers, and natural fibers. Fiberglass is the most common material used because of its cost to R-value options. The R-value on blanket insulation depends on thickness ranging from 8 inches at an R-value of 25 to 12 inches at an R-value of 38. The thicker the insulation, the higher the cost. You can expect the average cost of blanket insulation to run between $.15 cents to $.50 cents per square foot on average.

Benefits of Choosing Blanket Insulation

  • Low cost
  • Easy to install
  • Easy to replace (when required)

Drawbacks of Using Blanket Insulation

  • Lower thermal protection
  • Has to be checked and maintained to keep peak performance
  • Best when used in areas with limited to no obstructions
  • Possibility of mold and animal infestation

Loose-Fill Insulation

loose insulation for attic space

Loose-fill insulation is a spray-in insulation option that sits over the area as a loose filling. A loose-fill option is a great option if the attic has little to no headroom and lots of obstructions like vents and beams. Unlike the blanket installation that needs to be fit into place, loose-fill will fit into all nooks and crannies to create good coverage. Loose-fill insulation can also be placed on top of old insulation.

Loose-fill insulation comes in three different options fiberglass, cellulose, and mineral wool. Cellulose is the best rated loose-fill material as it is the most effective insulation with the highest R-value at the best cost per square inch. Cellulose is also rated as the best fire safety insulation as it packs itself in tightly and leaves little room for air, giving the fire little air to spread. Fiberglass is the most common loose-fill insulation purchased because of its cost to the R-value ratio.

The problem with loose-fill insulation is it can easily get moldy if moisture gets into the attic. It is also very dusty when installed. If a professional is used to install the product, they can add small amounts of water to cellulose material that lowers dust during installation and helps improve the price per square inch. Loose-fill insulation can be a DIY option, but it is suggested a professional installed it.

The product can be installed manually by spreading it, or for larger areas, a machine can spray the material. There is a fee to rent a machine to spread the product, but it is commonly a low cost or free rental if you get it when you purchase the insulation. The cost to have someone install the insulation for you is also commonly low.

The R-value of loose-fill insulation is calculated per square inch, with most products ranging between 2.2 to 3.8 depending on the product chosen as well as the depth and density of the filling.

Benefits of Choosing loose-fill insulation

  • Low cost
  • Easy to install
  • Easy to replace and can be placed over other insulation
  • Fire safety options available
  • Good for areas with lots of obstructions like beams and vents

Drawbacks of Using loose-fill insulation

  • Can easily move if there is a draft changing the rating in each area
  • Requires maintenance to keep it performing at its peak
  • Possibility of mold and animal infestation

Sprayed Foam Insulation

spray foam insulation used for attic space

Spray foam insulation is a foam that, when sprayed, bubbles up to fit a space. The Spray foam insulation is not a do it yourself option. It is best to have a professional come in to complete the installation. Spray foam insulation has the highest cost but also has the highest thermal protection, with R-values ranging from 3.5 to 6.5 per inch.

The rating depends on whether open cell or closed cell foam is used. Open-cell foam doesn’t close bubbles all the way, leaving the foam softer and more flexible. In comparison, closed-cell foam is denser with closed bubbles. Open-cell foam is cheaper with a lower R-value, while closed-cell foam is more expensive. The major difference between the two in cost and use is the expansion of the product. Open-cell expands and covers more area than closed-cell with fewer applications. Closed-cell foam cannot easily get into tight areas but can be used as a moisture barrier. Both open and closed-cell foam has air barrier protection.

Spray foam is made of polyurethane and commonly costs between $1 to $1.25 per square foot for open-cell foam and $1.25 to $1.50 per square foot for closed-cell foam.

Benefits of Choosing spray foam insulation

  • Does not require maintenance
  • Best thermal rating to protect your home
  • Moisture deterrent
  • Low indoor allergen production
  • Can help with sound reduction
  • Air barrier options

Drawbacks of Using spray foam insulation

  • Requires professional installation
  • High costs
  • Requires an airtight attic

There are pros and cons to each insulation type, and the decision should be made on the area in the attic that needs to be filled, the budget for the project, and the area that you live in. Make sure to check the R-value recommendations set by the DOE in your area as well as talk to a product specialist about what product will work best to fill the space in your attic.

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