A friend who is designing an elevated beach house asked me a question about the wind load underneath the house. He could not find provisions in ASCE 7. Should he consider wind load under the house? If no, why not? If yes, how?
There will of course be wind pressure (both suction and compression) on the first floor level. The reality is, however, that this is never likely to control the design. I doubt that designers of these buildings consider it (but don't know). The live load design for the floor (40 psf), factored by 1.6 will greatly exceed any factored wind load suction pressure. It would be difficult to get significant wind pressure pusing upward, but it would be a good idea to block the floor joists so that in the unlikely event this happens, the joists don't laterally torsionally buckle.
If the engineer wants to prove all this to himself, he could treat the floor as a "roof" and apply the associated pressure coefficients from ASCE 7