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Ken's E-Tip: Attic Insulation

If a person can only insulate one area, this would be the place to spend your money. Heat naturally rises and the attic insulation will do more to keep it in your home longer for you to enjoy. There are three basic types of attic insulation you can use in you home: 

  • Insulation Blankets - fiberglass or rock wool
  • Blown in Insulation - cellulose or fiberglass
  • Spray Foam - open or close cell

Our climate zone #5 calls for a total attic insulation value of R-39. By knowing the R-value per inch of various insulation materials, you can calculate how much is required to reach the desired insulation level.


Insulation Batts or Rolls - Fiberglass or Rock wool R-3+ per inch  

The most common attic insulation that can be purchased at home improvement stores is either fiberglass or rock wool insulation.  The tiny cotton candy like material earns its R-value by trapping air between tiny fibers. Be careful not to compress the material because it will squeeze out some of the air pockets reducing the R-value. Batts and rolls are basically the same with one difference. Batts are precut to fit common stud or joist cavities. Rolls are a long continuous version that one cuts themselves. 

Fiberglass and  rock wool are the least expensive insulation materials on the market. Be sure to wear protective clothing, gloves, and eye protection form tiny fibers that can cause skin and eye irritation.

The disadvantage of fiberglass or rock wool is that air moves through it and can greatly reduce it's insulating value. Also, the material loses most of it's properties if it becomes wet.


Blown In Insulation - Cellulose or Fiberglass R-3.5+ per inch         

This type of insulation is sold in compressed blocks which are broken down into tiny pieces by a powerful machine known as an insulation blower. The blower forces the insulation through a large hose. As the insulation flies out of the hose, the installer directs the flow of insulation into place. 

The most popular project for using blown in insulation is adding insulation to attics. Here, the insulation can be blown right over top of existing insulation to any depth or R-value. It's a fast and easy do-It-yourself project that two people can complete in an afternoon. 

Many cellulose products contain boric acid that has two great purposes. It is a fire retardant and insect repellant. Air does not move easily through cellulose, making it an excellent air barrier as well as an insulator.


Spray Foam Insulation  R-3 to R-8 per inch

Spray foam insulation is a combination of chemicals which are heated and sprayed out of a machine through a hose. The spray foam chemicals mix together at the tip of the hose creating a thick paint-like goo that sticks to anything it touches including wires, pipes and ducts. Within seconds, the foam begins to expand to trapping a gas inside billions of tiny bubbles. As the foam expands, it forms a continuous even layer of insulation and creates an air tight seal. There are two types of spray foam materials:

  • Open-Cell Spray Foam: The cheapest spray foam option is known as open-cell. So called because the bubbles inside of the foam never completely close. As the foam expands, air gets trapped in between the broken bubbles. This divides the space into billions of tiny air pockets that slow down heat as it tries to pass through. Open-cell spray foam is a much softer type of foam because of the broken bubbles. These bubbles allow water to pass through them, which can be good or bad depending on the application. Although open-cell spray foam does a great job at filling in and around wires, pipes and other obstacles, it's insulating power is not all that spectacular: R-3.5 per inch.
  • Closed-Cell Spray Foam: The bubbles or cells in closed-cell spray foam are closed and tightly packed together. This makes closed-cell spray foam much denser and stronger than open-cell spray foam. It will not absorb water or allow air to pass through it. This is because the bubbles in closed-cell foam are filled with a gas making them much smaller and a better insulator. Closed-cell spray foam tops the charts in insulating power with an impressive average of R-7 per inch. It is the most expensive form for insulating your attic, but gives a good payback in energy saved.


Now Is The Time 

Fall is a good time to complete sealing and insulating your attic for energy savings and comfort. Attic temperatures should be more tolerable and you will be doing your wallet a favor for years to come.



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