General Contractor Practice Exam

What is the rough opening required for store-front windows on the fifth floor with a 40 inch knee wall?

1. 4 feet

2. 4 feet 5 inches

3. 4 feet 11 inches

4. 5 feet

The correct answer is: 4 feet 11 inches

The calculation of the rough opening for store-front windows above a knee wall involves taking into account both the height of the knee wall and the desired height of the window. A standard window height is typically around 5 feet, but when there’s a knee wall present—such as a 40-inch (3 feet 4 inches) wall—the rough opening needs to compensate for this. To find the correct rough opening height, start with the standard height for a window, which is generally adjusted to allow proper installation and operation. When you align the bottom of the window's rough opening with the top of the knee wall, you need to add the knee wall height to the desired opening height of the window. When you add the height of the knee wall to the standard window height, you arrive at a rough opening height of 4 feet 11 inches. This takes into consideration that the window typically sits above the knee wall, rather than starting at the floor. Thus, the rough opening required for store-front windows on the fifth floor with a 40-inch knee wall is indeed 4 feet 11 inches. Understanding this calculation is crucial for ensuring that the window is installed correctly and meets building codes, while also considering aesthetics and functionality.