When a Housing Preservation and Development inspector finds a condition in an apartment or a common area, the violation is graded by how hazardous it is. Three letters do that work — A, B, C — and the city's file carries a fourth, I, which is not a hazard grade at all.
The three hazard classes
| Class | Means | Typical conditions | Records |
|---|---|---|---|
| A | Non-hazardous | Chipped paint in a low-risk unit, a missing sign | 2,550,073 |
| B | Hazardous | Leaks, mould, defective flooring, inadequate lighting | 5,223,999 |
| C | Immediately hazardous | No heat or hot water, lead paint risk, rodents, broken self-closing doors | 2,564,864 |
The classes carry different correction deadlines — an immediately hazardous condition has to be addressed far faster than a non-hazardous one — and they are certified back to HPD when the work is done.
A real Class C
This is an open violation recorded on 2 August 2026, quoted as the city wrote it:
§ 27-2005, 27-2007, 27-2041.1 HMC … REPLACE OR REPAIR THE SELF-CLOSING DOORS THAT IS MISSING OR DEFECTIVE LATCH SET AT VESTIBULE DOOR AT PUBLIC HALL, 1st STORY
A self-closing door sounds minor until you know why it is Class C: those doors are what stop a fire spreading into a public hallway. The class is a judgement about consequence, not about how big the repair is.
The fourth letter
Class I appears on 805,531 records, and it is not a hazard grade. Every one sampled carries the same charge:
§27-2107 ADM CODE OWNER FAILED TO FILE A VALID REGISTRATION STATEMENT WITH THE DEPARTMENT … AND IS THEREFORE SUBJECT TO CIVIL PENALTIES, PROHIBITED FROM CERTIFYING VIOLATIONS, AND DENIED THE RIGHT TO RECOVER POSSESSION OF PREMISES FOR NONPAYMENT OF RENT UNTIL A VALID REGISTRATION STATEMENT IS FILED.
Most residential buildings must register with HPD annually and name real people — a head officer and a managing agent — rather than only the company on the deed. A Class I violation records that this was not done. The consequences it lists are worth reading twice: an unregistered owner cannot certify their own violations as corrected, and cannot bring a non-payment case, until they register.
So a building with a Class I violation is not a building with an extra hazard. It is a building whose owner has not filed the paperwork that says who they are. If that is the question you came with, how to look up your NYC landlord covers where the ownership records live.
Not the same as the other agencies' classes
HPD's letters grade apartment conditions. The Department of Buildings uses type codes and a status category for its own violations — see DOB violation classes — and ECB summonses use numbered severities: what an ECB violation is. A class C and a Class 1 come from different agencies about different things.
Reading a building's record fairly
Volume alone says little: a large building has more apartments, more inspections and therefore more records. What is worth looking at is how many violations are open, how serious they are, and how long they have stayed open. A violation is a documented inspection finding on a date — not a statement about the people who live in the building, and not something to use in deciding whether to rent to somebody.
Sources: NYC Housing Preservation and Development — Housing Maintenance Code Violations (wvxf-dwi5). Counts are live totals on the date queried. General information about public records; not legal advice and not a tenant-screening tool.