The size and shape of the Glu-lam beams is defined by the loading conditions imposed on them by their span and the roof configuration.  The roof cantilevers 5 feet beyond the western beam and 2' beyond the eastern beam increasing the reaction at the west beam.  This condition results in a loading of 472# per foot along the glu-lam.  In addition, the glu-lam has a 3 foot cantilever at the south end but a 12 foot cantilever at its north end with a span of 18',  this produces a maximum moment of 33,984 foot pounds.  For strength alone, the beam would need a section modulus of 218.7in3, which translated to a 15 inch deep beam with a 6 inch width . . . However, it must be designed to limit deflection to at least l/360 because of the glazing that frames into the ceiling . . . With the relatively low modulus of elasticity of Southern Cypress at 1,100,000psi, and using  the deflection formula for a cantilever beam to solve for I (moment if intertia of the section) we develop a section that is 6in wide by 24 in deep at the greatest stress point . . . at the northern support point at the truss.  Other points are calculated in the same manner to solve for depth of beam, then we sculpt the shape to smooth the curves . . . And we arrive at the final beams.