Fire code issue? Need to fix on older properties ?

[Jason Bilbrey]

I’m looking at buying a duplex from 1974 in Wisconsin. The garages don’t have firewalls up to the roof to separate off the halves. This wasn’t a requirement for buildings when it was built. If I buy this property, could a tenant at some point mention its not up to current code and force me to fix it? The question is a general one for older buildings. If it was up to code when it was built, are older buildings grandfathered in?