Hi Chris. I'm building in Lower Alabama, near Pensacola, about 25 miles upriver from the coast.
L/900, not h/900. I'm referring to deflection of wood beams. Code specifies a maximum deflection of L/360 which is allows a deflection of 1/360th of the span. For instance, a 20' beam loaded to 60# plf at L/360 would have an allowable deflection of 0.667". The same beam at L/900 has a maximum deflection of only 0.287". I'm designing this house to be much stronger than code requires. This is last house I expect to build.
Code is quite inadequate, if you ask me. For instance, designing for 15 lb. psf roof live load meets code. I believe that a 125 mph hurricane wind with a duration of a very long time (seems like forever) will load a structure far beyond code requirements.