A referendum to place the duties of the Recorderâs Office into the County Clerkâs Office was passed by the voters of McLean County on November 6, 2012 and took effect December 31, 2013.
Depending on where you live, itâs recommended that attics have a minimum R-value of R-30 in warm climates to R-60 in cold climates. Recommended Insulation by Climate. By dividing the recommended R-value for your area by the R-value of your particular type of insulation, you find that an attic should have on average: Warm Climates (R-30 to R-49): 1  Fiberglass (blown): 14â â 18â. 2  Fiberglass (batts): 11â â 14â. 3  Cellulose (blown): 11â â 13â. 4  Rock Wool (loose): 12â â 18â. 5  Foam (sprayed): 5â â 11â.
Along with knowing the R-value of a particular insulation, it is also important to calculate the R-value of a total system. For example, a wall with 3 Â½â fiberglass batting (R-value of 11) may have an overall R-value of nearly 14 because of siding, sheathing and drywall.