CSLB General Building (B)Framing and CarpentryEasy
A framing contractor is installing a new roof on a residential project. The plans specify a ridge board. What is the minimum nominal thickness required for a ridge board in a conventionally framed roof?
- A1-1/2 inches
- B2 inches
- C1 inch
- D3/4 inch
Show answer & explanationAnswer & explanation
Correct answer: C. 1 inch
According to the IRC (International Residential Code), a ridge board must be at least 1 inch nominal thickness (actual 3/4 inch). Its depth must be at least equal to the cut end of the rafter where it abuts the ridge.
Why the other options are wrong
- A. This nominal thickness (actual 1-1/2 inches) is more commonly associated with a ridge beam, not a ridge board.
- B. This nominal thickness (actual 1-1/2 inches) is typically for ridge beams, which are structural elements, whereas a ridge board is primarily for rafter attachment and alignment.
- D. While 3/4 inch is a common actual thickness, the nominal thickness requirement is 1 inch.
Ridge Board Minimum Thickness
The minimum nominal thickness required for a ridge board, which serves as a non-structural element to align and connect rafters at the peak of a conventionally framed roof.
- Nominal thickness of 1 inch (actual 3/4 inch) is typical.
- Depth must be at least equal to the rafter depth.
- Primarily acts as a nailer and alignment guide, not a structural beam.
Memory trick: Board for alignment, Beam for big loads.