Residential Building Inspector B1Floor ConstructionMedium
An inspector is reviewing plans for a new residential structure where the floor system includes a girder supporting multiple floor joists. The plans specify a built-up wood girder consisting of three 2x10 members. According to the IRC, what is the minimum number of continuous rows of nails required to connect these members together?
- A4 rows
- B1 row
- C3 rows
- D2 rows
Show answer & explanationAnswer & explanation
Correct answer: D. 2 rows
The IRC specifies that individual members of built-up wood girders composed of three or more pieces of dimension lumber shall be fastened together with not less than two continuous rows of nails, one near the top and one near the bottom, staggered appropriately.
Why the other options are wrong
- A. Four rows are excessive for the minimum requirement and not specified by the IRC for this application.
- B. One row of nails is insufficient for a built-up girder of three or more members.
- C. Three rows are not the minimum requirement, though more rows would provide additional strength.
Built-up Wood Girder Nailing
Built-up wood girders, especially those with three or more members, require specific nailing patterns to ensure they act as a single unit.
- Two continuous rows of nails for 3+ members.
- Nails staggered at 32 inches o.c. for each row.
- One row near top, one near bottom.
Memory trick: Three-member girder needs two rows to bind.