Cindy Boucher wrote:

24 ft span... 2x8...

With a perfect splice, S = bd^2/6 = 1.5x7.25^2/6 = 13.1 in^3 and
M = fS = 13100 in-lb and W = 8M/L = 8x13100/(12x24) = 365 pounds
of total load, ie 15.2 pounds per linear foot or 11.4 psf on 16"
centers, if I did that right.

So maybe we need more than a perfect splice, eg a kingpost
or a truss or a wall under the middle.

Nick