Gypsum?

[Ean Savoy]

Any contractors/demo teams out there that have experience with older flooded houses? Currently doing a demo on my grandparents 1950s brick house that flooded in south Louisiana (Ascension Parish/St Amant). There is a 1/2 inch board (gypsum/pressed board?) nailed to the studs from the outside then brick installed outside that. My initial thought is that it needs to come out. Not sure how easy it will be to demo since its nailed from the backside. Does anyone know if I can just spray it with mold chemicals and paint over it with mold inhibiting paint instead of painstakingly knocking all this material out from behind the studs? Don't want to if we don't have to but I know the most important thing is to remove 100% of the mold before even thinking about going back up with Sheetrock. Thanks!