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Stesso

Calculate Rafter Length

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Learn framing fast 👍 hope this helps #learn #framing #carpentry #rafters

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What happens here

For rafters, first, measure the 'full measurement' from outside to outside of your framed wall. Let's say this is 40 inches. Split this measurement in half (20 inches). From this half measurement, subtract half the width of your ridge beam. If the ridge beam is 1 1/2 inches wide, subtract 3/4 inch (half of 1 1/2 inches). This gives you the 'run' (e.g., 19 1/4 inches). Next, determine your 'rise' or pitch; for example, a 6:12 pitch. Using a construction calculator, input the run (19 1/4 inches) and the pitch (6:12). The calculator will provide the 'rafter length' (e.g., 21 1/2 inches).

Goal: Calculate the precise 'run' and 'rafter length' based on wall width and desired roof pitch

Tools and materials

  • Construction Calculator — Calculating rafter run, rise, and length
  • Pencil — Making notes on the whiteboard
  • Tape Measure — Measuring the full width of the framed wall
  • Whiteboard — Demonstrating calculations

What they say

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rafters, the full measurement outside to outside, and we get 40. We'll split the measurement in half, and we get 20. And then, we subtract half the ridge beam. And this will give us 19 and a quarter for our run. Our rise will be a 6/12, but can be any number you choose. When we put the run and pitch in a calculator, it'll show our rafter length is 21 and 1/2. So, regardless if this goes up and down, this measurement does not change. The only thing that could change is the height of your seat cut. But typically, this will be the width of

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