figure out number of joists needed
Instructions. Measure the length and width of the room in inches. Calculate the number of joists you need by dividing the length of the room by 16. You use 16 because the floor joists will be placed no more than 16 inches apart. Measure the distance between each floor joist.While the standard distance is 16 inches, the gaps may be smaller.Add these measurements together to determine the amount of lumber you need for the blocking.ou use 16 because the floor joists will be placed no more than 16 inches apart. Measure the distance between each floor joist. While the standard distance is 16 inches, the gaps may be smaller. Add these measurements together to determine the amount of lumber you need for the blocking.