Massachusetts Construction Supervisor License (CSL) Practice Test

What is the maximum allowed projection of a nosing on a set of stairs with solid risers in a single family dwelling?

1. 1 inch

2. 1.25 inches

3. 1.5 inches

4. 2 inches

The correct answer is: 1.25 inches

The correct answer is that the maximum allowed projection of a nosing on a set of stairs with solid risers in a single-family dwelling is 1.25 inches. This guideline is specified in the building codes to ensure safety and accessibility in stair design. A nosing is the part of the stair that protrudes beyond the riser, and its projection is crucial for various reasons. First, having an adequate nosing helps to increase the tread depth, which can assist people in traversing the stairs more safely. A projection of 1.25 inches balances safety requirements with structural integrity. It provides enough surface for foot placement while not risking excessive overhang that could be susceptible to wear or damage. In regards to other potential projections, options such as 1 inch, 1.5 inches, and 2 inches either do not conform with current safety standards or could pose a risk. For example, a projection that exceeds 1.25 inches could create a tripping hazard, especially if the nosing wears down or accumulates debris over time. On the other hand, a projection of only 1 inch may not provide sufficient space for safe foot placement, which can lead to slips or falls. Therefore, the 1.25 inches