Residential Building Inspector B1Roof-Ceiling ConstructionEasy
A residential building inspector is examining the roof structure of a new home. The roof has a pitch of 4:12 and utilizes rafters for framing. What is the minimum required size for collar ties in this application, assuming a maximum rafter span of 20 feet and a spacing of 24 inches on center?
- A1x4
- B2x6
- C2x4
- D1x6
Show answer & explanationAnswer & explanation
Correct answer: A. 1x4
Collar ties are required to be a minimum of 1x4 in size when installed on the upper third of the rafter span, as per IRC R802.3.1. This size is typically sufficient for common residential applications.
Why the other options are wrong
- B. A 2x6 is excessive for a collar tie and is not the minimum requirement.
- C. A 2x4 is typically used for rafter ties or ceiling joists, not collar ties.
- D. While a 1x6 would be stronger, it is not the minimum required size.
Collar Tie Minimum Size
Collar ties, which resist rafter separation at the ridge, have specific minimum size requirements based on code.
- Collar ties are required to be a minimum of 1x4.
- They are installed in the upper third of the rafter span.
- They resist rafter separation at the ridge.
Memory trick: Collar Ties: 'C' for 'Connect' the 'Ceiling' at the 'Top'.