HPD Mold Violation — What NYC Landlords Must Do Next (Class B vs Class C)

The HPD violation notice arrived. Maybe it came after a tenant filed a 311 complaint you did not know was coming. Maybe it was the result of a routine inspection. Either way, you now have a legal document with a cure date, and the clock is running.

In Inwood’s pre-war rental buildings – six-story masonry walk-ups, aging plumbing, buildings that took on water during Sandy and Ida – mold violations are not rare. What is rare is a property owner who has a clean, documented process ready to respond. This guide covers exactly what the law requires, what the documentation needs to look like, and how to get a Certification of Correction filed before the cure window closes.

What is the difference between a Class B and Class C HPD mold violation?

HPD classifies mold violations by the size of the mold in a room. Class B (10-29 sq ft) is hazardous with a 30-day cure window. Class C is immediately hazardous (30+ sq ft of mold in a room) with a 21-day cure window. Both require a Certification of Correction filed with HPD after the landlord completes repairs.

In Inwood, most mold violations are Class A or B. In 2025, HPD issued 190 Class A, 173 Class B, and 33 Class C mold violations in ZIP 10034, across 128 buildings. See the year-by-year breakdown in our Inwood mold data report.

Class B – Hazardous. Approximately 30 days to correct the condition and file a Certification of Correction with HPD. Daily fines apply after the cure window if the violation remains open. This is the most common mold violation classification and covers most visible mold findings in residential apartments.

Class C – Immediately Hazardous. A shorter cure window – 21 days to correct the condition and file a Certification of Correction. Higher fines, faster escalation, and more urgent legal exposure. HPD classifies mold by size, not by who lives in the apartment: Class C is issued when there are 30 or more square feet of mold in a room.

Both violation types require the same legal process to correct – the difference is the timeline and the severity of consequences for non-compliance. Either way, the most important thing you can do after receiving the notice is start the process immediately, not at day 25 of a 30-day window.

How quickly do I need to act after receiving an HPD mold violation?

Immediately. Class C violations require correction within 21 days. Class B violations allow up to 30 days. Both timelines start from the date of the violation notice – not the date you read it. Contact a licensed Article 32 assessor within 24 to 48 hours of receiving any HPD mold violation.

Here is why the timing pressure is real even for a Class B with a 30-day window: the legal compliance process for mold in New York has multiple sequential steps, each of which takes time. You need to engage a licensed mold assessor – who needs to schedule a site visit, conduct air and surface sampling, send samples to an accredited lab, and produce a written remediation plan. Lab turnaround alone can take 5 to 7 business days. The written plan then needs to go to a licensed mold remediation contractor – separately licensed, because the same company cannot assess and remediate under Article 32. The contractor needs to schedule the work, complete it, and then a different assessor needs to conduct clearance testing before you can file the Certification of Correction.

In Inwood’s older buildings, where the moisture source often requires investigation – a slow pipe leak inside a wall cavity, a parapet flashing failure on the roof, a foundation drainage issue – the assessment phase can take longer than it would in a simpler building. Start immediately.

Does an HPD mold violation require a licensed contractor in NYC?

Yes, for mold projects over 10 square feet in buildings with 10 or more units. Article 32 requires a licensed mold assessor to write the remediation plan and a separately licensed mold remediation contractor to do the work. The same company legally cannot do both. Individual worker licenses also matter – a company license does not cover unlicensed workers.

Under NYS Labor Law Article 32, any mold remediation project above the 10-square-foot threshold requires:

1. A licensed Mold Assessor – conducts the initial assessment, produces the written remediation plan, and performs post-remediation clearance testing. Must be separately licensed from the remediator.

2. A licensed Mold Remediation Contractor – carries out the remediation per the written plan. Cannot be the same company or individual who did the assessment.

3. Individual Mold Abatement Workers – the workers who physically perform the remediation must hold individual Article 32 licenses, not just work for a licensed company.

A building super with a bucket of bleach does not satisfy any of these requirements. A general contractor without specific mold licensing does not satisfy them either. A Certification of Correction filed without licensed contractor documentation leaves you legally exposed – the correction is not valid, the violation remains open, and if the tenant or a judge looks at the paperwork, the absence of license numbers is immediately visible.

You can verify any New York mold license – assessor, remediator, or abatement worker – for free at dol.ny.gov. Do this before engaging any contractor, not after.

What is a Certification of Correction and how do I file one with HPD?

A Certification of Correction is a formal document submitted to HPD confirming that the violation condition has been fully remediated. For mold violations, a bare certification without supporting documentation is not sufficient – the Certification needs to be backed by a paper trail that demonstrates the work was done legally and thoroughly.

What that paper trail should include:

The assessor’s written remediation plan – produced before any work began, specifying the affected areas, contaminated materials, containment method, remediation approach, and moisture source findings.

Licensed contractor documentation – the remediator’s Article 32 license number, the specific scope of work performed, and the abatement workers’ individual license numbers.

Independent clearance testing results – air and surface samples taken by a licensed assessor who did not perform the remediation, with lab results from an accredited laboratory confirming the space is clean. This is the independent verification that the work was actually done correctly, not just that it was claimed to be done.

You file the Certification of Correction at hpdonline.hpdnyc.org or through HPD’s violation correction portal. After filing, track the violation status online – it should move to “certified” once HPD accepts the correction. If HPD re-inspects and finds the condition still present, the violation remains open and fines continue.

What happens if I ignore an HPD mold violation?

Ignoring an HPD mold violation triggers automatic fines that compound daily past the cure deadline, increases to more severe violation classifications, and opens the landlord to tenant HP Action proceedings in Housing Court. HPD can also initiate emergency repairs and bill the landlord at a premium rate.

Daily fines. HPD charges daily fines for violations that remain open past their cure window. These accumulate and can become significant over weeks and months.

HP Action in Housing Court. Once a tenant sees an open violation on hpdonline.hpdnyc.org, they have everything they need to file an HP Action in Housing Court. A judge can order you to complete repairs on a court-imposed timeline and impose contempt sanctions for non-compliance. You are now a defendant in a court proceeding rather than managing a violation on your own schedule.

Property record impact. Open violations appear in your property’s public record. They are visible to prospective buyers, lenders, title companies, and anyone conducting due diligence on the property. An open HPD mold violation is a material encumbrance that affects financing, sales, and refinancing.

HPD permit implications. Owners with open violations can face complications obtaining other HPD permits and approvals. If you have any planned renovation or capital work requiring permits, an open mold violation can become a blocking issue.

Ignoring the violation does not make it go away. It compounds the legal and financial exposure with every week that passes.

What typically causes mold violations in Inwood’s pre-war buildings?

We see a predictable set of root causes in the buildings along Payson Avenue, Seaman Avenue, Post Avenue, and the Dyckman corridor. Understanding them matters because the remediation plan – and the Certification of Correction – is only valid if the moisture source is addressed, not just the mold.

Supply riser leaks inside wall cavities. The copper risers in 1920s masonry buildings develop pinhole leaks that can saturate wall cavity materials for weeks before reaching the surface. The visible mold is in the apartment; the actual moisture source is inside the wall. Remediation that addresses the wall surface but not the riser will fail – the mold will return, usually within a season, and you will have a second violation.

Bathroom exhaust failure. Original exhaust systems in these buildings often run into shared shaft systems that no longer provide adequate draw. Bathroom moisture has no exit path and condenses repeatedly on walls and ceilings. Remediation without addressing the ventilation failure is a short-term fix.

Sandy-era and Ida-era foundation moisture. Buildings along the lower-grade streets east of Broadway – and basement units throughout the neighborhood – still carry legacy moisture from 2012 and 2021 storm events that was never professionally dried. Mold in these locations is often deep in wall cavities and concrete block, and it requires more than surface treatment to address.

Roof and parapet leaks. Top-floor mold violations frequently trace to failing roof membrane sections or parapet flashing that is not obvious from inside the apartment. The assessor’s written plan needs to identify this as the moisture source, or the remediation will not hold.

How we help Inwood landlords respond to HPD violations

We handle the Article 32 licensed assessment side for Inwood landlords responding to HPD violations – the independentt evaluation, written remediation plan, and post-remediation clearance testing that the Article 32 process requires and that a Certification of Correction needs to stand on.

We know Inwood’s building stock. We know where the moisture typically comes from in a six-story pre-war walk-up, what a legitimate scope of work looks like for the common violation conditions in these buildings, and what clearance testing needs to show before you file a Certification that will hold up. We work with property owners who need to move fast, and we understand the cure-window pressure.

Call (917) 694-9003. Tell us the violation class and the location. We will tell you what the assessment process looks like, how long it takes, and whether the timeline works for your cure window.