NASCLA Accredited Commercial General ContractorWoodHard
A structural engineer specifies the use of heavy timber construction for a new commercial lodge. According to the International Building Code (IBC), what is the minimum nominal dimension required for columns in Heavy Timber (Type IV) construction?
- A10 inches by 10 inches
- B8 inches by 8 inches
- C6 inches by 6 inches
- D12 inches by 12 inches
Show answer & explanationAnswer & explanation
Correct answer: B. 8 inches by 8 inches
According to IBC Section 602.4 (Type IV Construction), columns in heavy timber construction must have a minimum nominal dimension of 8 inches by 8 inches. Beams and girders require a minimum nominal dimension of 6 inches in width and 10 inches in depth, or 8 inches in width and 8 inches in depth. This question specifically asks for columns.
Why the other options are wrong
- A. 10x10 inches exceeds the minimum, but 8x8 is the code minimum.
- C. 6x6 is the minimum for beams/girders in one dimension, but not for columns, which require larger dimensions.
- D. 12x12 inches exceeds the minimum, but 8x8 is the code minimum.
IBC Heavy Timber Columns
Minimum nominal dimensions required for wood columns in Type IV (Heavy Timber) construction as specified by the International Building Code.
- Type IV construction relies on large timber members for fire resistance.
- Minimum nominal dimensions are specified for columns, beams, and arches.
- These dimensions provide inherent fire resistance through charring.
Memory trick: For heavy timber, eight by eight is the column's fate, to meet the code at the gate.