Final answer:
The maximum allowed depth of a notch in a bearing wall can vary, but newer research suggests a maximum depth of 15 times the diameter of the notch.
Step-by-step explanation:
The maximum allowed depth of a notch in a bearing wall varies depending on the age of the rule. An older "rule of thumb" suggested a maximum depth of 7-8 times the diameter of the notch. However, newer research suggests that the maximum depth can be as much as 15 times the diameter of the notch.