Roaches from basement to first floor

[Meng W.]

Hi BP. I am having a bit of a conflict, hope someone can help me. 

My previous basement tenants were vendors that sold food out on thw street. They would make the food in the basement and sell in the morning. The tenant moved out months ago and ever since i renovated the basement my first floor who lived here 6 years has been complaining more heavily on the roach situation. First floor claims and believes that it is coming from the basement and after the renovation more roaches are coming to them. Keep in mind that the first floor has a backyard and they cook alot also.

Now my question is since i live in nyc am i ( the landlord) responsible for roach issues. I have given them treatments for it i.e. powders, and traps. I read the guidelines for nyc however im getting different opinions.

Please advise anyone