Numbers of roommates allowed in San Diego?

[Steven Nguyen]

Hi everyone, we are a family of three lived in a 5 bedrooms in San Diego.  Currently we rented out three spare rooms to 4 unrelated people as roommates.   My next door neighbor is not happy about that for whatever reasons.  My questions are: 

1) how many roommates am I allowed to have legally?

2) How do the city even enforce it if four roommates are too many?

3) if someone from the city came out to check,  can they get in the house if I don’t want them to?

Thanks