What beam means
A beam is a horizontal structural member that carries loads across a span to posts, columns or walls.
Where it matters on a carpentry job
Beam size depends on span, load and species or product, so it comes from a table or an engineer. Check the bearing at each end too; a big beam on a skinny post is still a failure.
What the model code says
- The ends of each joist, beam or girder need at least 1 1/2 inches of bearing on wood or metal and 3 inches on masonry or concrete, or approved hangers. (IRC 2021, Chapter 5)
Check which code edition your building department enforces for beam before you quote.
Work it out
- Free calculator: Framing calculator
- Tools, templates and guides: Free carpentry resources
Sources: 2021 International Residential Code, Chapter 5, Floors (ICC). Checked October 9, 2026.