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Attic Insulation 101: Types, Costs, Benefits & More

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Attic Insulation 101

The attic is a space in your home that is often forgotten about. Most homeowners don’t even consider it until there is something wrong that needs attention, such as a leak in the ceiling or a rodent infestation. However, before you adopt the out of sight out of mind mentality, there are a few things you should know about the benefits of attic insulation.


Attic Insulation Prolongs the Life of Your Roof

In winter, warm air rises and escapes through the ceiling and into the attic. Both these instances cause your heating and cooling system to work hard to maintain a comfortable indoor temperature. In the summertime, improperly insulated attics can reach temperatures of up to 140 degrees. As a result, the strength of the wood is being pulled out as it sweats from the heat. Over time, sap and amber crystals start to form, plywood will pull apart, and your rafters will start to split and crack. If left unaddressed, you will be faced with structural problems requiring costly restoration that requires a professional assessment from a structural engineer. In addition, any qualified roofer won’t touch your house with a ten-foot pole. So, if you are in need of a new roof you will be out of luck. 

Another issue homeowners face as a result of improper attic insulation is wood rot. When you heat your home the hot air from the inside rises and meets the frigid air in the attic creating condensation. This condensation if left unattended will rot the wood in your roof from the inside out. In addition, the nails used to create your roof structure also get cold and start to create “cat eyes” which exacerbate wood rot, eventually leading to major damage. 

Even in mild climates, an improperly insulated attic creates an opportunity for wood rot. Every day the average house creates 2 gallons of moisture. And where does the moisture go? Up into the attic.

Attic insulation prevents the damages mentioned above and also prolongs the life of your roof by: 

  • Preventing gradual damage to your home caused by heat and moisture and preventing water vapor from seeping in and eroding your walls or causing mold to form. 
  • Slowing down heat buildup in your attic, which can cause the shingles on your roof to swell and crack or cause the plywood on your deck to soften. 
  • Preventing ice dams from forming when melting snow refreezes on your roof’s edge. 

Attic Insulation Increases the Energy Efficiency of Your Home

In the cooler climates, improperly insulated attics result in up to 50% of your home’s heat being lost directly through your roof. In fact, the US Department of Energy estimates that boosting attic insulation can lower heating costs by 10 to 50%, saving the average homeowner about $780 per year.

Savings don’t stop at heating costs. A properly insulated attic also reduces energy costs in the spring and summer months by reducing the need for air conditioning systems. It also reduces the stress on your mechanical systems, prolonging the life of your furnace and air conditioning units. 

In addition to financial savings, attic insulation makes your home more comfortable year-round by stabilizing your home’s indoor temperatures. Have you ever been annoyed at the drastic temperature difference between the first and second floors of your home? With improper insulation, the large open space of your attic contains a hot cloud of air just sitting there. This contributes to your house being hot upstairs and nice downstairs and can be eliminated with proper insulation. 


Radiant Barrier Insulation: Your Attic’s Secret Weapon

A radiant barrier is specialized roof insulation that reduces attic temperatures by up to 30 degrees in the summer. It is used in conjunction with regular attic insulation to further stabilize the temperature of your home and also protects your attic from the damaging effects of heat on its structure. 

Imagine the sun shield you put in the front window of your car when you leave it parked in the sun for a long period of time. The shield reflects the heat of the sun back out of your car, thus reducing the inside temperature so you aren’t sweltering when you get in. 

A radiant barrier acts in the same way, reflecting the heat of the sun back out of your home through the roof, thus reducing the temperature of your attic. Its application is simple, attaching to the bottom side of the rafters and in warmer climates, it reflects and reduces the radiant energy of the sun by 97 percent. In the winter months, radiant barrier insulation pushes the warm air from your furnace back down into your home and reflects the cold air back out through the roof.

Insulation alone can handle up to a 20-degree temperature change from your attic to your home. Meaning, if the temperature in your attic is 120 degrees in the summer, the interior of your home might get down to 100 degrees which is still too hot. By adding a radiant barrier, you reduce the temperature of the air in your attic first, by 30 degrees with this barrier attached to your attic’s ceiling. Then, you further reduce that temperature with the regular insulation barrier on the floor of your attic. Now, your home went from 120 degrees to 90 degrees, to 70 degrees. A much more manageable temperature.  

This “double-duty” system works both in the summer and the winter, stabilizing the temperature in your attic and transferring that stabilization into your home. 

Common types of attic insulation:

Batt Insulation

  • Common and cost-effective, batt insulation provides basic coverage. It’s quick and affordable, comes in various thicknesses and widths and comes with or without a paper facing.
  • Installed by hand rolling on the attic floor. 
  • Works best for attics with standard joist spacing, few obstacles to work around and sufficient headroom for maneuvering during installation. 

Blown-in Insulation

  • With a high percentage of recycled content, blown-in is eco-friendly and very energy efficient. It provides a dense, effective barrier against heat loss in attics. 
  • Installed with special machinery to blow in place to the desired depth and density. 
  • Works best for attics with irregular joist spacing, lots of obstacles, and limited headroom for maneuvering. 

Spray Foam

  • Least common for residential applications as it is expensive and cannot be removed. It comes in two varieties—open-cell and closed-cell and is by far the best insulator on the market. 
  • Installed with special machinery to spray it onto the roofline of your attic where it expands and creates a vault-like seal.
  • Works best for attics with structural and mechanical elements that will not need to be accessed in the future. 

Understanding R Values 

R-value tells you your insulation material’s ability to resist transmitting heat. The higher the number in the R-value, the more effective the insulation is. If your attic insulation R-value is correct for your house, it means that you’re likely working at high efficiency based on the current attic insulation standards. Houses built before the 1970s probably have an R-value of 11 or less, but today’s standards call for R-values as high as 38 or more, depending on the codes in your home’s location. 

Check out these helpful graphics from to discover the recommendations for your location.


Once you have determined your homes recommended insulation level, check out your current situation. If you do have insulation, you can assume that one inch of insulation is equal to an R value of 3. Therefore, the depth of the insulation will determine its overall R value.

However, if you notice that your insulation is water stained, deteriorated, compressed, or moldy, the integrity is compromised and it is not working properly. If you see shiny flecks in your insulation these could be vermiculite from a mine with asbestos deposits and should be tested and removed by a professional. 

What Should My Attic Look Like?


According to the North American Insulation Manufacturers Association (NAIMA), 90% of single-family homes in the US are under-insulated. Is your home one of them? 

Investing in proper attic insulation is a one and done project that lasts a lifetime. And, let’s face it, roof repairs aren’t cheap, and most insurance companies won’t cover roof replacements due to negligence or lack of proper home maintenance. At Kapella Roofing, we typically install 17” of blown-in insulation to an R-value of 49. We will come inspect, measure, and give you an attic insulation quote free of charge and obligation. 

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