My Pennsylvania house was built in 1978. The insulation was improperly installed with the vapor barier placed to the outside. There does not seem to be moisture damage to the framing in the two rooms where we have removed a small section of dry wall to check. Shoud we replace the insulation even though there appears to be no damage after 25 years. Is there any method to this mad installation technique? We have heated the 2080 sq. ft. of living space with only 500 gallons of oil each year for the 16 winters we lived here.