Hello. 
I wanted to get some advice on insulating the first floor of a two family home in zone 4A. The second floor would not get insulated. I have aluminium siding with the older asphalt siding beneath it. There’s no sill plate. The floor joists are embedded in the rim joists. Also, the wall cavity on the first and second floor is seperated by what I assume to be floor boards. 
My contractor said he can take down the aluminium siding, drill holes and blow cellulose in the walls. 
I wanted to know if this will cause any moisture or mold problems down the road since only our unit would be insulated. 
Thank you!