What is the minimum size for a roof ridge board?
A ridge board must be at least 1 inch nominal thickness and no less in depth than the cut end of the rafter (IRC R802.3).
Where rafters meet at a ridge, they must be placed directly opposite each other and nailed to a ridge board. The ridge board supports and aligns the rafter ends in a conventionally framed roof.
The IRC requires the ridge board to be at least 1 inch nominal in thickness and not less in depth than the cut (plumb) end of the rafter, so the full bearing of the rafter is supported.
A non-structural ridge board is different from a structural ridge beam; a ridge beam is sized by engineering when it carries roof loads instead of relying on ties.
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Ask Donnie →General information based on the International Residential Code (a model code). This is AI assistance to verify — not legal advice. Confirm the adopted edition and any local amendments with your local building department (AHJ) and a licensed professional before you build.