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https://www.homebuildingandrepairs.com/engineering/index.html - Ever wonder why the International Residential Code (IRC) requires a floor joist to sit a minimum of 1.5 inches on a wall framing plate or beam? In this video, we break down the actual math structural engineers use to come up with that number.
Using a standard residential living room example (20-foot span, 16" O.C. spacing, 40 lb live load, and 15 lb dead load), we walk step-by-step through how to calculate the reaction force and the exact surface area your joist needs to safely rest on the plate.
While 1.5 inches works for most standard builds, longer spans and heavier loads change the math completely. We'll also cover what to do when your calculations require more bearing length, including how to eliminate the rim joist in favor of full bearing and blocking on a 2x4 or 2x6 wall.
In this video, you will learn:
The IRC minimum bearing distance for joists
How to calculate the reaction force of a floor system
Factoring in live loads, dead loads, and joist spacing (16" O.C.)
How to calculate the required surface area based on wood strength
Framing solutions for long spans that exceed the 1.5-inch rule
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