Conversion of two family to three

[Ryan Judy]

Does anyone have any experience converting a two family to a three, or doing major renovations of a two / three family?

It is somewhat town specific but I am having trouble interpreting fire code for automatic sprinklers on a large renovation. Town says I will need to install them but If I am reading code correctly it should only apply to new construction buildings over 4 units. 

https://malegislature.gov/Laws/GeneralLaws/PartI/TitleXX/Chapter148/Section26i

They also don't seem to give specifics on what "substantially renovated is" But a court case ruling gave this clarification: 

“… in order to require the installation of sprinklers in an existing multi-unit residential building, the rehabilitation must be so substantial that the physical structure is rendered ‘the equivalent of new construction,’ i.e., in essence as good as new. Where the rehabilitation is suitably substantial in this regard, a corollary is that the cost of installation of automatic sprinklers ordinarily will approximate the cost of installing sprinklers in a comparable newly constructed building.”