stlouislofts.com is a great spot for finding many different lofts that are either under development or are already completed in the Washington Avenue area. Any lofts that are in the 63103 zip code fall into the HUBZone.
Here are links to specific lofts around the area: Wash Ave, Soulard, CWE, etc. You will need to double check the addresses against the HUBZone locator to ensure that you are looking at a loft in the HUBZone. (https://eweb1.sba.gov/hubzone/internet/)