I'm building a 12x24 building with 8' of the roof 10psf. being supported with one 2x12 on each side cantaleverd 8'from the other 16' of the building. Will a single 2x12 on either side of the 8 x 12 roof support the roof being cantaleverd?

  • So you're building a 12x16 building with a roof that cantilevers 8'-0" beyond the exterior wall? "Cantilever" means a diving-board-like structure without any support at its tip. This is what you have in mind? No posts at the tip? And this 10psf? This is a dead load? Live load? Snow load?
    – popham
    Nov 4, 2023 at 8:30
  • Please post a plan, a hand drawn one is fine Nov 4, 2023 at 10:04
  • Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking.
    – Community Bot
    Nov 4, 2023 at 10:05
  • I suppose it depends on the uncantilevered length...
    – Huesmann
    Nov 4, 2023 at 17:44

1 Answer 1


The International Residential Code (IRC) that governs most residential construction in the US provides for short cantilevers in some situations. 8'-0" cantilevered from a 16'-0" is way out of bounds for IRC tables. You would need an engineer to size beams for this cantilever.

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