Understanding the 25 Contiguous Square Feet Rule

Do You Need a Licensed Mold Contractor? Understanding the 25 Contiguous Square Feet Rule

Updated September 2026: This article has been revised to reflect more recent guidance concerning which surface materials are included when determining whether mold contamination affects 25 contiguous square feet or more

When Texas homeowners, property managers, or contractors discover mold, one of the first questions is whether the work must be performed by a licensed Mold Remediation Contractor.

The answer depends on more than the dimensions of the visible spots. Under the Texas mold rules, the calculation is based on the contiguous area of surface material that needs to be cleaned or removed to remediate identified visible mold contamination. However, otherwise unaffected surfaces are not automatically included merely because they are inside containment or will receive routine cleaning.

The Rule in Plain English

Texas Occupations Code §1958.102 provides a licensing exemption for a person who is not licensed under the Texas mold law when the mold contamination affects a total surface area of less than 25 contiguous square feet.

The threshold is 25 square feet or more, not more than 25 square feet. An area measuring exactly 25 contiguous square feet is not considered “less than 25” and therefore does not qualify for the minimum-area licensing exemption.

The Texas mold rules define “total surface area of contiguous square feet” as:

“the contiguous area of surface material that needs to be cleaned or removed to remediate visible mold contamination.”

The important question is not simply how much visible discoloration can be measured. The question is how much contiguous surface material must reasonably be cleaned or removed to remediate the identified visible mold contamination.

Visible Mold Markings and the Remediation Area

The area included in the calculation is not necessarily limited to the precise outline of visible mold markings.

For example, visible fungal growth may affect part of a drywall panel, but removing only the visibly discolored section may not be practical or sufficient. A larger contiguous section of drywall may need to be removed to reach clean, dry, and unaffected material. When that additional removal is reasonably necessary to remediate the visible mold contamination, the larger section may be included in the calculation.

The same principle may apply to cabinetry, insulation, framing, or other building materials. What counts depends on the materials, the extent and configuration of the contamination, and the remediation reasonably required.

This does not mean that every nearby surface must be counted. There must be a reasonable relationship between the identified mold contamination and the surface material that needs to be cleaned or removed.

What Does Not Automatically Count?

Mold remediation projects commonly involve containment, HEPA air filtration, HEPA vacuuming, damp wiping, and final cleaning. These procedures help control dust and remove particulate disturbed during the work.

Routine cleaning does not automatically make an otherwise unaffected surface part of the mold-contamination area.

The following surfaces should not be included automatically merely because they receive routine cleaning:

• Walls and flooring inside containment
• Unaffected cabinetry or countertops
• Personal belongings protected or cleaned during the project
• HVAC registers or components located within the work area
• Surfaces receiving precautionary HEPA vacuuming or damp wiping
• Surfaces treated only as a preventive measure
• Critical barriers and other containment materials

The size of the containment area also does not determine the square footage of mold contamination. Containment may be larger than the affected material because workers need sufficient space to perform removal, operate equipment, package debris, and prevent particulate migration.

Similarly, the possible presence of microscopic or settled spores does not automatically make every nearby surface part of the regulated surface-area calculation.

How the 25 Square Feet May Be Evaluated

The following examples demonstrate the difference between affected material and routine project cleaning.

• Mold-Affected Drywall

Visible fungal growth affects a portion of a drywall surface. The remediation requires removal of a larger contiguous section to reach clean and unaffected material.

The drywall section reasonably requiring removal may be included in the calculation. Unaffected flooring and adjacent walls that receive routine cleaning inside containment are not automatically added.

• Mold Inside a Sink Cabinet

Visible mold contamination affects the cabinet bottom, shelf, and adjoining cabinet components. Those materials may require cleaning or removal and should be evaluated as part of the affected surface area.

The kitchen floor, countertop, unrelated cabinets, and personal belongings do not automatically count merely because they are located near the work area or will be cleaned as a precaution.

• A Small Area Inside a Larger Containment

A limited area of drywall requires remediation, but a larger containment is established to isolate the work.

The containment dimensions do not determine the mold-contamination area. Routine final cleaning of unaffected walls and flooring within the containment does not, by itself, increase the affected surface area.

• Concealed Mold Discovered During Removal

An area initially believed to be less than 25 contiguous square feet is opened, revealing additional mold contamination inside the wall or cabinet assembly.

The newly discovered material may increase the actual contiguous area requiring remediation. If the total reaches 25 contiguous square feet or more, the project may no longer qualify for the minimum-area exemption. The scope and applicable regulatory requirements should be reevaluated before work continues.

Should Separate Mold Areas Be Combined?

Separate, noncontiguous areas should not automatically be added together and treated as one contiguous area without an appropriate regulatory basis.

For example, an affected area under a kitchen sink and a separate affected area in an upstairs bathroom are not necessarily one contiguous mold-contamination area simply because both will be addressed during the same project.

However, what initially appears to be separate contamination may be connected through a shared wall cavity, continuous building material, cabinetry, an HVAC component, or another concealed area. The determination depends on the actual configuration and extent of the affected materials.

This is one reason square footage cannot always be determined reliably from photographs or estimates provided before an inspection.

What Happens at 25 Contiguous Square Feet or More?

When mold contamination affects 25 contiguous square feet or more, the minimum-area licensing exemption does not apply.

Unless another statutory or regulatory exemption applies, the project may be subject to requirements established by Texas Occupations Code Chapter 1958 and 16 Texas Administrative Code Chapter 78. Depending on the project, these requirements may include:

1. An assessment performed by an appropriately licensed mold assessor.
2. A mold remediation protocol prepared by a licensed Mold Assessment Consultant.
3. A mold remediation work plan prepared by a licensed Mold Remediation Contractor.
4. Submission of a Mold Remediation Notification to TDLR.
5. Remediation performed by appropriately licensed or registered individuals.
6. Compliance with applicable documentation and minimum work practices.
7. Post-remediation assessment and clearance.
8. Completion of the applicable Certificate of Mold Damage Remediation process.

Mold assessment and mold remediation are separate activities under Texas law. The assessor evaluates the extent of the mold contamination and prepares the remediation protocol. The remediator prepares the work plan and performs the remediation.

Because the law includes exemptions in addition to the minimum-area exemption, reaching 25 square feet does not determine the requirements for every project without considering the particular circumstances.

The Licensing Exemption and TDLR Notification Are Separate Issues

The minimum-area provision is a licensing exemption for certain persons performing work involving less than 25 contiguous square feet.

TDLR’s notification requirement is separate. TDLR states that a Mold Remediation Notification is required when mold contamination affects a total surface area of 25 contiguous square feet or more and mold remediation will be conducted, unless an applicable exemption changes that requirement.

A project affecting less than 25 contiguous square feet does not require a TDLR Mold Remediation Notification. However, this does not mean that every person performing the work is exempt from all provisions of the mold law and rules.

Licensed Mold Remediators Remain Subject to the Rules

A licensed Mold Remediation Contractor who accepts a project is not exempt from the mold law and rules merely because the affected area is less than 25 contiguous square feet.

TDLR explains that the minimum-area exemption applies to persons who are not licensed to conduct mold remediation and was intended to allow small projects to be handled more simply. When a consumer hires a licensed Mold Remediation Contractor for a small mold-remediation project, the contractor must comply with the requirements applicable to the license.

According to TDLR, this includes preparing a work plan that follows a remediation protocol developed by a licensed Mold Assessment Consultant. A notification is not required when the mold contamination affects less than 25 contiguous square feet.

Other Texas Mold Exemptions

The less-than-25-square-feet exemption is not the only exemption available under Texas law.

Texas Occupations Code §1958.102 and 16 Texas Administrative Code §78.30 contain separate exemptions that may apply to certain property owners, tenants, managing agents, employees, residential properties, construction or improvement activities, and other defined circumstances.

Each exemption has its own conditions and limitations. A project should not be assumed exempt solely because it involves a homeowner, residential property, maintenance employee, or construction contractor.

The applicability of an exemption should be evaluated using the current law and rules and the specific facts of the project. TDLR can provide regulatory guidance, while questions requiring legal advice should be directed to a qualified Texas attorney.

Why an Accurate Assessment Matters

Determining the affected surface area may require more than measuring visible spots. A mold assessment may consider:

• The type and dimensions of the affected materials
• Whether the materials can be cleaned or require removal
• The practical limits needed to reach clean and unaffected material
• Moisture readings and the suspected source of moisture
• Whether contamination may extend into concealed areas
• Whether affected surfaces are actually contiguous
• The possibility that the remediation scope may change during removal

A remediation protocol should distinguish between mold-contaminated material requiring remediation and otherwise unaffected surfaces receiving routine containment or final cleaning.

If concealed mold contamination is discovered, the remediator should notify the appropriate parties so the scope and regulatory status of the project can be reevaluated.

Frequently Asked Questions

Does exactly 25 square feet qualify for the minimum-area exemption?

No. The exemption applies to mold contamination affecting less than 25 contiguous square feet. Exactly 25 square feet is not less than 25.

Does the entire containment area count?

No. The containment boundary does not determine the affected surface area. The calculation concerns the contiguous surface material that needs to be cleaned or removed to remediate visible mold contamination.

Does every surface that receives HEPA vacuuming count?

Not automatically. Routine HEPA vacuuming, damp wiping, or final cleaning of otherwise unaffected containment surfaces does not, by itself, make those surfaces part of the mold-contamination area.

Is the calculation limited to the exact visible mold markings?

Not necessarily. A larger section of contiguous surface material may be included when cleaning or removing that material is reasonably necessary to remediate the identified visible mold contamination and reach clean, unaffected material.

Can concealed mold change the original determination?

Yes. Additional contamination discovered during removal may increase the actual area requiring remediation. If the area reaches 25 contiguous square feet or more, the minimum-area exemption may no longer apply.

The Bottom Line

The 25-contiguous-square-feet calculation is based on the surface material that needs to be cleaned or removed to remediate identified visible mold contamination.

It is not automatically based on the size of the containment, every surface receiving final cleaning, the possible presence of settled spores, or every material listed in a remediation protocol.

At the same time, the calculation is not necessarily limited to the exact outline of visible discoloration. Additional contiguous material may count when its cleaning or removal is reasonably necessary to complete the remediation.

Because concealed conditions and the configuration of affected materials can change the determination, property owners and contractors should avoid relying on photographs or rough estimates alone when a project appears close to the threshold.

Related Articles

• Texas Occupations Code Chapter 1958
• TDLR Mold Laws and Rules
• TDLR Mold FAQs
• TDLR Mold Remediation Notifications

• Understanding the Texas Mold Law
• When Is a Licensed Mold Consultant Required in Texas?
• Mold Assessment vs. Mold Testing
• What Is a CMDR?
• Post-Remediation Verification

Dennis Butts is a Texas licensed Mold Assessment Consultant and principal of NTX Enviro Consulting Services, providing mold inspections, remediation protocols, and post-remediation verification services throughout North Texas.

NTX Enviro provides professional mold inspections and moisture evaluations for homeowners throughout North Texas.