How to Determine the Number of Risers Required for Stairs

How to determine the number of risers required and their unit rise?

When building a stair with a total rise of 7'7", the number of risers required and their unit rise is _____. Option 1: 14 risers with a unit rise of 6 inches. Option 2: 15 risers with a unit rise of 5 inches. Option 3: 16 risers with a unit rise of 6 inches. Option 4: 17 risers with a unit rise of 5 inches.

Answer:

The correct option is Option 3: 16 risers with a unit rise of 6 inches.

When building stairs, it is essential to determine the number of risers required and their unit rise to ensure the staircase meets the desired specifications. In this case, we are working with a total rise of 7 feet and 7 inches.

To determine the number of risers required and their unit rise, we need to divide the total rise by the desired unit rise. In this case, the total rise is 7 feet (84 inches) + 7 inches, which equals 91 inches.

Now, let's analyze each option provided:

• Option 1: 14 risers with a unit rise of 6 inches would result in a total rise of 14 × 6 = 84 inches, which is not enough to reach 7 feet 7 inches.
• Option 2: 15 risers with a unit rise of 5 inches would give a total rise of 15 × 5 = 75 inches, which is insufficient for the specified height.
• Option 3: 16 risers with a unit rise of 6 inches would provide a total rise of 16 × 6 = 96 inches, exceeding the required height.
• Option 4: 17 risers with a unit rise of 5 inches would result in a total rise of 17 × 5 = 85 inches, still falling short of the necessary height.

Therefore, Option 3 is the correct choice as it gives a total rise of 96 inches, which is more than the required 91 inches for a total rise of 7 feet 7 inches.

In conclusion, when building a stair with a total rise of 7 feet 7 inches, the optimal configuration is Option 3: 16 risers with a unit rise of 6 inches. This setup ensures the stairs reach the specified total rise effectively.