Interpretation #9533
Published May 20, 2026
Original Request
- Code Version
- 2023
- Code
- EXTBLDG
- Code Description
- Chapter
- 8
- Section
- 807.4 & 807.5
- Topic
- Level 2/3 alteration
Question
Does section 807.4 & 807.5, exception 1, assume that an existing structural element was originally designed to or near 100% utilization? If so and if the existing structural element is not reduced in capacity, then can this exception be satisfied by only considering the additional demand? Refer to additional information in comment section.
Answer Published 05/18/2026 at 9:05 AM
The referenced code sections do not assume anything. The engineer must calculate the capacity of the beam, its current loads and the proposed loads. In the example, if the beam had plenty of capacity there is no need to utilize the exception. The exception is only used if the proposed additional loads exceed the beams capacity calculated according to the current codes. Then the beam is ok if the proposed load only exceeds the current load by 5% max.
Commentary
None.