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4 Types of Insulation That Work Every Time

Insulation keeps your home warm in the winter and cool in the summer. There are several common types of insulation: fiberglass (in both batt and blown forms), cellulose, rigid foam board and spray foam.  Each type of insulation has advantages and disadvantages.  When correctly installed with air sealing, each type of insulation can deliver increased comfort and lower energy bills during the hottest and coldest times of the year.


  • Most effective when used in the high density batt formulation for interstitial wall areas (i.e. inside stud walls.)
  • Loose fill blown in fiberglass is the most common new construction insulation. However, loose fill fiberglass has very low density per cubic foot and suffers from convective R-Value degradation.
  • Actual realized R-Value on blown in fiberglass can be as low as 50% of the theoretic value in certain applications, so the R-Value advertised is not what you are actually yielding in the home.  It is a best practice to adjust your blown in totals to account for the realistic R-Values projections.  


  • Cellulose is the most effective of the loose fill insulations.
  • The higher density per cubic foot of cellulose largely eliminates the convection issue and provides a much more accurate R-Value per inch.
  • Be sure to specify borate only stabilized cellulose and avoid all ammonium-stabilized products.  Borate only stabilized cellulose does not have VOC content and does not off-gas in the same manner as ammonium sulfate stabilized cellulose or formaldehyde containing fiberglass.
  • While more expensive than blown fiberglass insulation, the energy savings with the higher actual realized R-Value will balance out the initial investment over time while maintaining a higher comfort level within your home.

Rigid Foam Board

  • Rigid foam board has excellent application value in the right scenarios.
  • It is very effective for usage in basement wall insulation projects as well as behind knee walls and under “hot” roof decks.
  • Rigid foam board is great at maintaining its R-Value regardless of conditions and can more easily be installed in vertical applications as well as is used to create a complete thermal break.
  • Be sure to check with your local fire and building codes to see if they require a thermal or ignition barrier to be code compliant.

Spray Foam

  • Spray Polyurethane Foam (SPF) insulations are very versatile and have a great capability range.
  • SPF is an excellent air barrier as well as insulator, so it serves two purposes by helping to reduce air infiltration while insulating the space.
  • Closed Cell foams also function as a vapor retarder and can be used in lieu of, in permitted applications.
  • SPF is expensive and therefore is not as widely used as other insulations.

Hiring a professional Weatherization Company with ENERGY STAR rating ensures real energy savings and safe results, without causing problems with indoor air quality or moisture.  To speak with one of the energy experts from Windows on Washington about how the correct type of insulation can be applied to your home for the greatest increase in comfort and highest return on investment, click below or call us at 703-378-1190.

Air Sealing and Insulation eBook

Topics: Air Sealing and Insulation