Insulation is measured in R-values—the higher the R-value, the better your walls and roof will resist the transfer of heat. DOE recommends ranges of R-values based on local heating and cooling costs and climate conditions in different areas of the nation. State and local code minimum insulation requirements may be less than the DOE recommendations.

If you are considering increasing your current insulation package, insulation is cumulative.  If your attic currently has an R-22 (9”) and you add another R-22 (9”) you will have an R-49 (18”).

• Inside of a thunderstorm there are strong updrafts of warm air and downdrafts of cold air.
• If a water droplet is picked up by the updrafts...it can be carried well above the freezing level. With temperatures below 32F...our water droplet freezes.
• As the frozen droplets begin to fall they are carried by cold downdrafts, but it may thaw as it moves into warmer air toward the bottom of the thunderstorm
• The half-frozen droplets may also get picked up again by another updraft...carrying it back into very cold air and re-freezing it.
  

Ventilation of the home attic is important for two reasons. During the summer, excess heat that builds up in the attic during the day results in high energy costs for cooling. Also, moisture produced within the home may move into the attic if ceiling vapor barriers are not used. If this moisture is not exhausted from the attic it can condense and cause insulation and construction materials to deteriorate. Thus, temperature and moisture control are the major reasons for providing attic ventilation.