A ventilated insulation bat having longitudinal channels formed in the top of the bat. The channels are resiliently compressible and flattenable when the bat is rolled, but the channels resume their depth when the bat is unrolled. The channels are manufactured by means for forming such as by molding or melting the channels into the bat or by affixing a flattenable perforated corrugated device to the bat. The transverse distance across the flattenable perforated corrugated device extends less than the width of the bat. The flattenable device when flattened is smaller than the bat to prevent the device from extending beyond the width of the bat when the bat is compressed and rolled into a roll for storage or transportation.
