In reply to SV reX :
Very true. 
Easy enough to lower the window opening before hand. Give me the room depth and overhang width and I can detail the overhang. Minimum roof pitch is 4/12 for shingles.
In reply to SV reX :
Very true. Easy enough to lower the window opening before hand. Give me the room depth and overhang width and I can detail the overhang. Minimum roof pitch is 4/12 for shingles.
In reply to VolvoHeretic :
True, but I am assuming there is a reason for the small header. (For example, the window height conflicts with the foundation knee wall height, or other pre-existing condition)
In reply to SV reX :
I did request pictures earlier. 
Just build it conventionally with individual headers and keep it simple.
Nothing about this is conventional. The roof is steel. It will be a 2:12 pitch. Yes, I know that is shallow even for a steel roof, but it can be done with the proper precautions. And yes, I've calculated the soffit return.
The total wall height on the inside is 6'6" (old farmhouse, low ceilings throughout)
Need bottom of window to be at least 32" above top of floor for planned cabinets/ work counter
Thought about using 30" high windows instead of 36", but Mrs. VCH wants max light.
Window spacing is non-negotiable from ends, due to symmetry of the inside rooms (there's going to be a dividing wall; one room will have 4 windows and one room will have 3)
Is there a structural issue to using 2x6's horizontal (6" side flat) vs. vertical? In other words, is there any difference if I run (3) 2x6's standing up (total height 5.5") vs 4 flat (total height of stack 6")?
In reply to volvoclearinghouse :
Yes.
It's not a header if you lay them flat. It's a quadruple top plate.
On the one hand, I've already said that you don't even need a header. On the other hand, I NEVER build an exterior opening in a wall without a header.
If your rafters are stacked on top on your studs, it's fine. But that will make weird spacing for your rafters.
Your inspector probably won't like it.
Wall section: Uses 2x10 roof rafters with 8" fiberglass insulation (r-25) and leaves about 3/4" of air gap under the roof sheathing for ventilation. No problem with 24" overhangs. I would just add one more 2x6 laid flat to bring the top of the window down a little from the soffit. Typical t.o. door and window is around 6'-10".
I would install 24"x42" (2'-0" x 3'-6") windows.
In reply to SV reX :
Right. Either I stack the rafters on top of the wall studs for direct load-in-bearing, or I header the windows with 2x6's. If I go the direct load-in-bearing approach, I calculate I'll need 16 rafter beams, so there's no spacings greater than 2-0 and every rafter sits directly over a stud . But that messes with the insulation, as typically insulation rolls are 16" or 24". Basically would have to cut a few strips narrower. Bleh, I hate fiberglass.
If I go with window headers I'll need 14 rafters, and regular insulation roll widths/ standard rafter spacing. And its more conventional.
In reply to volvoclearinghouse :
That 24" span will support the roof without a header. How much does the 1-1/2" extra span width add to the load on the top plates? Adding an extra 2x6 above the window will only add capacity. I think that load transfer travels in a 90 degree cone, so 45 degrees downward on either side of the rafter.
Here is the IRC regarding top plates in relation to wall stud and roof rafter spacing.
The above is from the 2018 version of the IRC, but it should still be relevant. Several of the rafters are 5-1/4" away from the nearest stud but that is moot because as drawn there are (3) 2x6 top plates.
Any pictures yet?
In reply to VolvoHeretic :
A building inspector who wants to be a stickler could (theoretically) say that doesn't apply, because the windows make the stud spacing 25 1/2" oc, not 24" oc.
I know that seems nitpicky, but Ive definitely met that guy.
In reply to SV reX :
I agree. Too bad the only way to know is to ask a structural engineer and get their blessing and stamp of approval.
We still need to know the depth of the addition to calculate the loads on that window wall.
In reply to VolvoHeretic :
Meh. He's already said he's using 2x6s. He'll be fine.
Considering this entire assembly is a structural header, the inspector isn't going to give a tin whistle about whether it is a double or triple top plate.
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