This appears to be a great site for calculating header and beam requirements: http://learnframing.com/wood-beam-calculator/ But it distinguishes between interior and exterior beams -- and the results are very different. I am adding an addition to my one-story house. I am knocking a 10' wide door between the existing building and the addition. This door is going into the existing "exterior" wall. But when things are finished it will be in an "interior" wall. I have calculated the weight, and added the weight of the new roof to the existing. But I can't understand the tool's differences for interior vs exterior and hence not sure which to use.

  • Seems to me after reconstruction on the exterior wall would be defined as an interior wall while the new external header carries the new external load of the roof and 2nd floor – Tony Stewart Sunnyskyguy EE75 May 14 '18 at 1:31

Think of it as “bearing” and “non-bearing” walls.

Although, when I tested the beam calculator out, it is not accurate. It’s very conservative...especially the end bearing requirements.

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