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Resource · Law & complianceNYC Mold Rules: A Licensed Contractor Is Required at 10 Square Feet
HPD mold violations require licensed remediation — not a handyman with paint.
Reading time 8 minutes · Legal explainer
The Law Gives Tenants Rights and Landlords Deadlines — Here Is Both
Two layers of law govern every mold obligation in this city: one state, one municipal.
The state layer is Article 32 of NY State Labor Law, effective 2016 and administered by the NY State Department of Labor mold program. It creates the licensing regime: who may assess mold, who may remediate it, and the requirement that those two roles be held by separate entities on the same project. It sets the 10 square foot threshold above which licensed work is required.
The municipal layer is Local Law 55 of 2018, the Asthma-Free Housing Act, codified at NYC Admin Code §27-2017.1 through §27-2017.12. It makes indoor mould an owner responsibility in multiple dwellings, requires owners to investigate and remediate, and gives HPD its enforcement powers. HPD’s adopted indoor allergen hazard rules set out the work practices owners must follow.
If you are a tenant: you can report a mould condition and have it inspected. Where the condition exceeds 10 square feet, licensed professionals are required. You can file a complaint through 311 if the owner does not act.
If you are a landlord or building owner: you must respond to an HPD violation within the correction period stated on the notice, and that response must involve licensed professionals for any condition above the threshold. Paint and cleaning do not satisfy the requirement.
Both sides come with documentation requirements. The law specifies what must be produced in writing before work begins and after it ends. That paperwork is what closes the violation — not the physical work alone.
What Happens After an HPD Mold Notice
HPD issues mold violations to building owners when a tenant complaint is substantiated during an inspection.
HPD classifies mould conditions by severity, and the classification determines the correction window. The most serious class — Class C, immediately hazardous — carries a 21-day correction period, and violations can be upgraded if an owner fails to certify or correct. Penalties attach to violations that stay open.
Here is what correcting actually means, and where owners most often run into trouble. Sending a maintenance worker to clean or paint over a mould condition above the threshold does not satisfy the requirement. Remediation must be performed by a licensed mould remediation contractor operating under a written work plan prepared before work begins.
HPD re-inspects. If licensed remediation has not happened — documented with the required paperwork — the violation stays open. An open violation accrues civil penalties and creates problems at lease renewal, sale and refinancing.
The threshold is measured by affected area, and it does not require a single contiguous patch. Multiple smaller areas in the same unit can combine to cross it.
What the Rules Actually Require: The Full Picture
Provision by provision — read what applies to your situation.
The 10 Square Foot Threshold
Article 32 establishes the point at which licensed work is legally required: any mould condition at or above 10 square feet. Below it, remediation is not a licensed activity, though owners of multiple dwellings still carry obligations under Local Law 55 and must follow safe work practices.
One detail many property owners miss: the threshold applies to the affected area overall, not per patch. If one moisture source has caused mould in three locations totalling 12 square feet, the licensed requirement applies to the full scope.
The Mold Remediation Work Plan
Before a licensed contractor begins remediation above the threshold, a written work plan is required — a document specifying the affected area, the containment design, the removal methods and the post-clearance testing protocol.
The work plan is not optional. It establishes what the job covers and what conditions must be met before occupants return. Without one, there is no legal baseline for the remediation that follows, and it must be prepared by or under the direction of a licensed mould remediation contractor.
The Assessment Requirement and the Two-Company Rule
Mould assessment is a separate licensed activity from remediation, with its own credential. The assessor inspects the condition, identifies the moisture source, and produces a written assessment that defines the remediation scope.
The assessor and the remediation contractor cannot be the same company on the same project. That separation is written into Article 32 specifically to remove the incentive to overstate a problem in order to sell a larger job. Mold Water Remediation is the licensed remediation contractor; the assessor is independent of us.
Post-Remediation Clearance
After remediation is complete, clearance testing is performed by the independent assessor to confirm that airborne spore levels have returned to acceptable conditions. It demonstrates that the condition has been corrected and the space is safe for re-occupancy.
The clearance report is the document that closes the violation. Without it, the record stays open even where the physical work was done correctly.
Tenant Protections During the Work
Where remediation requires a tenant to vacate, the owner carries responsibility for the displacement and must give written notice of the work scope, the timeline and the arrangements.
Owners should confirm the current requirements with counsel or HPD before scheduling, as the notice obligations depend on the building type and the scope of work.
Common Scenarios in NYC Buildings
Three situations that come up regularly across New York City’s rental building stock.
The Bronx owner who used maintenance staff
A South Bronx owner receives a complaint about roughly 14 square feet of mould on a bedroom exterior wall. A maintenance worker cleans and repaints it in an afternoon. HPD re-inspects and the violation is still open: no licensed contractor, no work plan, no clearance. The owner now faces an open violation, re-inspection, and the same licensed job still ahead. Engaging licensed professionals from the start resolves the requirement correctly the first time.
The Brooklyn tenant who filed a complaint
A tenant in Flatbush notices a dark pattern along the base of a bedroom wall and estimates it at 8 square feet. She contacts 311. HPD inspects and measures the condition at 11 square feet — above the threshold. A violation is issued, and the owner is now required to produce a work plan, arrange licensed remediation, and submit clearance documentation to close it.
The co-op board that acted quickly
A Jackson Heights board discovers mould in a shareholder’s unit after a roof leak. The managing agent engages an independent assessor and a licensed remediation contractor. A work plan is produced within 48 hours, remediation follows, and clearance testing is performed when work is complete. The violation closes without penalty, and the documentation supports the building’s insurance claim for the leak event.
From the field
Why the Paperwork Matters as Much as the Work
“HPD does not close a violation based on what was done. They close it based on what can be verified.
When a building gets a mould violation, the instinct is to fix the problem as fast as possible. That is the right instinct. But fast and documented are not the same thing.
Running remediation jobs across New York City since 2016, I have seen this pattern consistently. The work plan, the clearance report, the contractor licence number — those are what get reviewed when the paperwork arrives. If any piece is missing, the violation stays open.
The Bronx carries a high concentration of open mould violations because the borough has dense pre-war housing stock with aging plumbing and inadequate ventilation. We reach South Bronx jobs via the Major Deegan Expressway and northern Bronx jobs via the Cross Bronx. Neither route requires going through Midtown.
When we take a job, the work plan is written before anyone enters the unit with equipment, and the independent assessor is scheduled before remediation is complete rather than after. That sequence is what produces a usable clearance report on the first attempt.
Mold Water Remediation Corp holds NY State Mold Remediation Contractor License #24-6A4P4-SHMO, issued July 2, 2024 by the Division of Safety and Health in Albany. It is verifiable through the state, and every job produces written documentation structured to support violation closure.
When the Rules Require a Licensed Contractor
The legal threshold is 10 square feet. The practical decision point is usually earlier.
- The visible mould area is at or above 10 square feet — a single patch or combined areas
- You have received an HPD violation notice for a mould condition
- The mould has returned after a previous cleaning attempt
- The moisture source was a pipe leak, roof leak or flooding event — not just surface condensation
- Multiple areas in the same unit are affected
- An inspector is scheduled to re-inspect an existing violation
- The condition involves a wall cavity, subfloor or ceiling assembly rather than a visible surface only
Below the threshold a licensed contractor is not legally required, but the underlying moisture source still needs addressing — mould returns when moisture returns. Even below it, a written record of what was done demonstrates good-faith compliance if the condition recurs. Where the question is simply which side of the line you are on, our DIY versus licensed remediation guide covers it directly.
How to Verify a Contractor Before You Hire One
Every licence in this system is checkable, and checking takes minutes rather than days.
Mould remediation licences and mould assessment licences are both issued by the New York State Department of Labor, and both are verifiable through the NY State Department of Labor mold program. Ask for the licence number before work is scheduled, not after.
Two things are worth confirming specifically. First, that the credential matches the work — an assessment licence does not authorise remediation, and a remediation licence does not authorise assessment. Second, that the assessor and the remediator are genuinely separate entities, because a single company holding both roles on your project is not permitted.
A contractor who cannot produce a licence number, or who offers to both assess and remediate the same job, is offering something the law does not allow. Mold Water Remediation Corp operates under License #24-6A4P4-SHMO as the remediation contractor, and the clearance assessment on every job is performed by an assessor independent of us.
Areas We Serve
Mold Water Remediation serves all five New York City boroughs from our Brooklyn dispatch location.
Our licensed crews respond to HPD violation situations, post-inspection remediation jobs, and conditions identified during routine building maintenance. The dispatch at 1419 Coney Island Ave reaches every borough without routing through Midtown.
Understanding the Law Is the First Step. Licensed Remediation Is the Next.
Have your building address, the violation number if one has been issued, and a description of the affected area ready. We will tell you what the job requires and what the documentation will cover.
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