I need to support a ridge beam on one end with a Douglas fir 6 x 12 x 12 ft long header. The load will be on a single point in the center and will be about 8000 lbs total. I can't tolerate sag as there is an expensive door/window assembly installed below. I cannot find single point header tables anywhere and don't care to enlist an engineer as most will not work on a single component basis. My experience and gut says it's good but I want to prove the math. Any suggestions?
Yes, a 6 x 12 Douglas Fir-Larch (#2 and better) with a 12’ span will support 8,000 lbs. at mid-span. It’s deflection will be less than 1/3 inch when fully loaded.
If the 6 x 12 is a Select Structural, then it will support 10,300 lbs. and deflect about 1/4”.
BTW, I recommend the window (vinyl, wood, whatever) that you are going to install below this beam should NOT be secured at the head in the middle one-half of the span.