Rio said:
Whoops! How does 5'-10" and 2 jack studs on each side sound?
I would have to say that I agree with you because I got the same answer. Either we are both right or we both made the same mistake. I'll explain how I think we came to the same conclusion.
Remember we are looking for a 40# GSL which is not on the Table so we have to split the difference between the 30 & 50
Using Table 502.5(1) from the IRC, I went down to the section that supports a center bearing floor above, ceiling and roof. When I took the row for (2)2x10 and went to the 28' wide column under the 30psf GSL, I got 6'2" of maximum span.
I then continued over to the same column in the 50# GSL for a 28' wide building and got 5'6". Both required double jack studs for this header size. The difference between 5'6" and 6'2" is 8" so we split the difference and have a choice of either subtracting 4" from 6'2" or adding it to 5'6". Either way we come up with 5'10".
So the answer is that the maximum span for a double 2x10 header on an exterior wall that supports a center-bearing floor above, ceiling and roof with a 40# GSL is 5'10" and must include double jack studs.
If, however, the 30 had given us single jack studs and the 50 gave us double jack studs, I would err on the side of caution and require 2 jack studs just to be safe.
