• A typical 2500 sq.ft. home has over 1/2 mile of cracks and crevices, even if new construction.
  
• Enough air escapes through a typical house every day to fill 2 Goodyear blimps.
  
• Increasing R-values may deliver minimal returns:
  

Fouriers law of Thermodynamics states that 93% of conductive heat flow is already stopped in R-12 insulation specification. Increases above R-12 may not deliver expected payback.It's the fact of having a "tight home" that provides you with the greatest savings. Up to 40% of energy loss in a home is related to air leakage not R-value in the home. Fiberglass insulation will achieve the R-value it specifies only in the ideal situation. Once fiberglass is exposed to drafts or difference in air pressure between the exterior of the home and interior of the home its' R-value drops significantly, this does not happen with spray foam insulation which in fact makes it far superior to Fiberglass as an insulation material.