A carpenter is framing a rough opening for a standard exterior door that is 914 mm wide by 2032 mm high. Assuming a standard jamb thickness of 38 mm (1.5 inches) and a typical head clearance, what is the most appropriate rough opening width and height?

Question: A carpenter is framing a rough opening for a standard exterior door that is 914 mm wide by 2032 mm high. Assuming a standard jamb thickness of 38 mm (1.5 inches) and a typical head clearance, what is the most appropriate rough opening width and height?

Answer options:

• 922 mm wide x 2038 mm high
• 938 mm wide x 2050 mm high ✅ 950 mm wide x 2060 mm high
• 940 mm wide x 2040 mm high

Correct answer: 950 mm wide x 2060 mm high

Explanation: A common practice for rough openings adds 50 mm (2 inches) to the width of the door for shimming and 60 mm (2 1/2 inches) to the height for the head jamb and shimming. This results in a rough opening of 914+50 = 964 mm wide by 2032+60 = 2092 mm high. However, if the question asks for a slightly tighter fit, adding 38-50 mm for width and 50-60 mm for height is common. Option C provides 914+36 = 950 mm and 2032+28 = 2060, making it a plausible fit for typical doors including an allowances for shims at the sides and head.