Hello, the OSB is the sheathing which was placed under the new Hardie Board a few months ago. The House was built in 89 an had T1-11 and LP1 siding which was stripped. There was no backing behind the T1-11. The attic has 6 sofit vents on one side and 3 on the opposite. In addition, it has two gable vents. No roof vents. Thanks!