Zoning laws do not have limits as to the depth of a basement or the height of the first floor as long as the first floor does not exceed the height restriction for the structure. Height restrictions for a structure in residential neighborhoods of single family homes are determined by the local zoning laws.
The local building department is responsible for approving the sight engineering plans that effect the water run off of the property and it's effect on surrounding properties.
All this information is available as public record, contact the building department and zoning department to get the information you require for the property next door.
Best Regards
Bill Vojta
Associate Partner
Keller Williams Prestige
60 Long Ridge Rd.
Stamford CT 06902
p: 203.425.9868
url: http://billvojta.youkwagent.com