Peer-to-Peer Standards Exchange

Both ASCE 24 and 44 CFR Parts 59 and 60 have long prohibited sub-grade parking under residential in flood zones.

But both allow sub-grade parking under non-residential in flood zones.

ASCE 24 allows sub-grade parking under mixed-use in flood zones.

The allowance for mixed-use is problematic.  A tiny amount of non-residential added to an otherwise residential building allows sub-grade parking.

44 CFR Parts 59 and 60 avoid the loophole with the introduction of "other residential".  The current draft revision of ASCE 24 still suffers from the loophole.

A related issue:  does the mere addition of sub-grade parking to an otherwise residential building make it mixed-use?

The definition of mixed-use would improve if sub-grade parts of a building were excluded from counting as a non-residential use.