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Add insulation to your attic to increase the R-value

R-value measures the resistance of a material to heat flow. A higher R-value provides more insulation, which saves you money by reducing heating and cooling costs. A well-insulated attic can make your home more comfortable and quieter, reduce the risk of moisture damage, enhance fire safety, make your home more disaster-resistant, and help guard against pipe freezing.

 
 
Costs Annual Savings Time
DIY*: varies money*: varies DIY*: 6-8 hours
Pro*: varies carbon*: varies  
   
Difficulty Recurrence  
medium None  
 

Installing Attic Insulation
Better insulation in the attic can cut energy use in some homes by 40%.
The minimum required R-value of your insulation varies according to the state or region in which you reside. Typically, you should insulate your attic to at least R-38, or approximately 10-15 inches, depending on the type of insulation you use. Insulate to a higher R-value if you live in a colder climate.
In a typical home, half or more of the energy loss is through the exterior walls, floor and roof. Proper insulation, as well as sealing air leaks in your home's shell, is vital to reducing these energy losses. Insulating to a higher R-value would provide additional energy savings.
If you decide to have extra insulation professionally installed in your attic, the approximate price range is $.80-$1.10 per square foot. Prices vary by region, type of insulation, and the level of accessibility of your attic.

How To

1. Determine whether the existing insulation in your attic is adequate. If you can see the floor joists, you should add more insulation. If you can't see the floor joists, you likely don't need to add more insulation.
2. Seal any large air leaks in your attic and basement. Leaks in both the attic and the basement can change the effectiveness of your attic insulation.
3. If you choose to add more insulation, decide whether to install it yourself or have a contractor install it. The easier it is to access your attic and move around in it, the easier it will be to install insulation yourself.
4. Buy the correct width of insulation materials. You can determine the width you will need by measuring the area between the joists in your attic.
5. Before installing the insulation yourself, make sure you are completely covered up by wearing long pants, a long sleeved shirt, goggles, gloves and a face mask. Avoid breathing in insulation fibers and getting them on your skin and in your eyes.
Important: If your attic has vermiculite insulation, it may contain asbestos. Be sure to get this type of insulation tested by an approved lab before making any changes to it. To get the names of approved labs, contact your local health department.

Tools and Materials

  • Insulation
  • Instructions that came with the insulation
  • Staple gun and staples
  • Work lights or flashlight
  • Utility knife
  • Straight edge
  • Broom handle (for positioning insulation in harder-to-reach places)
  • Attic rafter vents/baffles
  • Plywood to create a temporary walk-way across the insulation

Tips and Tricks

  • A higher R-value is better. Insulation needs to be thick enough to keep out the elements. Have an inspector look at your existing insulation's R-value, or its resistance to transferring heat. You should have at least an R-38 for attic space (depending on where you live) and R-13 for walls so your air-conditioning or heating system doesn't have to work as hard.
  • Compare contractors' bids based on R-value. When comparing contractors' bids, make sure they are for the same insulating value (R-value), not just the same number of inches.
  • Attic access helps determine the type of insulation to use. If access to your attic is limited, blown-in cellulose or fiberglass insulation is your best bet.
  • Consider using cellulose insulation. If you are doing the installation yourself, consider using cellulose. Cellulose insulation is less expensive and has a higher R-value per inch than fiberglass, and will not irritate your skin and lungs.
  • Check for holes in the attic floor. Make sure all holes in the attic floor are sealed before you install insulation.
  • Check for a vapor retarder. Make sure there is a vapor retarder between the attic floor and the insulation to help prevent excess moisture from condensing on the insulation. However, if you are adding insulation on top of pre-existing insulation, don't install a vapor retarder, since it may trap moisture in the old insulation underneath.
  • Do not block the attic vents with insulation. Proper attic ventilation is important in maintaining an R-value. Attic ventilation also helps your home stay warmer in the winter and cooler in the summer while using less energy.
  • Check the evenness, thickness, position, and dryness of your insulation. The insulation on your attic floor should be uniformly thick and distributed evenly with no gaps. The vapor barrier side should be facing downward -- toward the living space you are trying to keep warm. Also, the insulation should be dry.
  • Before adding insulation, check for black-stained areas on the edges of fiberglass in your attic. Go into the attic and looking for black-stained areas on the edges of the fiberglass. That's dust, and it shows where air is flowing up out of the living space. Sealing that area first will do more good than simply piling on more insulation.
  • Observe the interaction of snow and ice with your house. Does snow melt from your roof rapidly? That means heat is escaping from your home through the roof and you should consider adding more attic insulation. Rapid formation of icicles without a thaw is another indication that you're losing heat through the roof. If you find that you are losing a lot of heat through your roof, evaluate the thickness and uniformity of the insulation on your attic floor.

* The amounts referenced are estimates and can vary significantly. Read the FAQ for more information.


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