School Indoor Air Quality Programs: Preventing Summer Mold Before It Starts

---

Every summer, school districts across the country face the same avoidable problem. Teachers and staff return to prepare classrooms for the new school year only to discover musty odors, visible mold, elevated humidity, or water-damaged materials.

In many cases, the issue is not caused by a major flood or obvious leak. It develops gradually while school buildings sit unoccupied during summer break.

Schools that are not fully climate controlled during warmer months can experience higher-than-normal indoor temperatures and relative humidity levels. HVAC systems may also operate on reduced schedules to conserve energy. When these conditions continue for several weeks, moisture can accumulate in building materials, furnishings, and HVAC components, creating an environment where mold can develop.

By the time the problem is discovered, the district may be facing an urgent mold assessment, remediation work, damaged materials, temporary classroom closures, and possible delays to the start of school.

The good news is that many summer mold problems can be prevented or minimized through a proactive indoor air quality program.

Why Mold Problems Develop During Summer Break

During the school year, buildings receive regular attention from teachers, custodians, administrators, and facilities personnel. Heating, cooling, and ventilation systems also tend to operate more consistently while buildings are occupied.

Summer conditions are different.

Many schools reduce HVAC operation when students and staff are not present. At the same time, warm, humid outdoor air can enter through doors, windows, ventilation systems, and gaps in the building envelope.

Summer maintenance activities can also introduce moisture. Carpet cleaning, floor care, painting, construction work, roof leaks, plumbing issues, and condensation may all contribute to damp indoor conditions.

Materials commonly found in schools can absorb and retain moisture, including:

• Ceiling tiles
• Drywall
• Carpeting
• Books and paper products
• Upholstered furniture
• Insulation
• Wood and composite materials

Areas with limited air circulation may be particularly vulnerable. These can include storage rooms, libraries, portable classrooms, basements, rooms along exterior walls, and spaces located at the ends of HVAC zones.

Because these areas may receive little attention during summer break, developing problems can go unnoticed until staff return.

The Cost of Waiting Until August

A mold problem discovered in June or July may be manageable. The same problem discovered days before students return can quickly become an operational emergency.

A reactive response may require:

• An urgent indoor air quality or mold assessment
• Moisture testing and investigation
• Development of a remediation plan
• Mold remediation and cleaning
• Removal and replacement of damaged materials
• HVAC cleaning or repair
• Temporary classroom closures
• Relocation of students or staff
• Accelerated contractor schedules
• Communication with parents and employees

School districts may also face additional costs when work must be completed under a tight deadline. There may be less time to compare contractors, plan work efficiently, or coordinate repairs around normal operations.

In more serious situations, affected classrooms or buildings may not be ready for occupancy when the school year begins.

That can create first-day delays, room changes, scheduling difficulties, and understandable concern among parents, teachers, and administrators.

Proactive IAQ Programs Help Identify Problems Earlier

A proactive indoor air quality program allows school districts to identify moisture, humidity, ventilation, and building-condition concerns before they become larger problems.

Depending on the needs of the district, evaluations may be conducted quarterly, biannually, or at key times during the school calendar.

A proactive program may include:

• Visual inspections for mold, moisture, and water damage
• Indoor temperature and relative humidity measurements
• Review of summer HVAC schedules
• Inspection of areas with previous moisture problems
• Moisture measurements of suspect materials
• Review of building-envelope concerns
• Identification of condensation
• Recommendations for corrective action or continued monitoring

The goal is not simply to test the air for mold. Mold spores are naturally present in indoor and outdoor environments.

The more important objective is to identify whether building conditions are allowing unwanted mold growth and to correct the source of the moisture.

Why Summer Is the Right Time to Evaluate School Buildings

Summer provides an important opportunity to evaluate how school buildings perform during warm, humid, and reduced-occupancy conditions.

An inspection during the summer can help facilities teams determine:

• Whether indoor humidity is under control
• Whether HVAC systems are operating as intended
• Whether certain rooms are warmer or more humid than others
• Whether leaks or condensation are affecting materials
• Whether carpet cleaning or other maintenance activities introduced excess moisture
• Whether previously affected areas remain dry
• Whether there is enough time to complete corrective work before staff return

A district that identifies elevated humidity in July may be able to adjust HVAC schedules, repair equipment, improve air circulation, dry affected materials, or address a leak before extensive mold growth develops.

That is more manageable than discovering the same condition immediately before the first day of school.

---

Practical Steps Schools Can Take

School districts can reduce summer mold risk through several practical measures.

Maintain Humidity Control

An unoccupied building still requires appropriate moisture control. HVAC schedules should be based on indoor humidity and building conditions, not temperature alone.

Conduct Routine Walkthroughs

School buildings should be inspected periodically throughout the summer. Staff should look for musty odors, condensation, staining, damp materials, and visible mold growth.

Monitor High-Risk Areas

Portable classrooms, basements, libraries, storage rooms, locker rooms, and areas with a history of leaks should receive additional attention.

Address Water Intrusion Promptly

Roof leaks, plumbing failures, window leaks, and drainage issues should be investigated and corrected quickly. Wet materials should be dried as soon as possible.

Manage Cleaning Activities Carefully

Carpet cleaning and floor maintenance should be scheduled when sufficient air movement and drying time are available.

Check HVAC Components

Drain pans, condensate lines, coils, filters, and controls should be inspected to confirm that systems are operating properly and not contributing to excess moisture.

Track Recurring Conditions

Repeated humidity or moisture issues may indicate a larger HVAC, roofing, drainage, or building-envelope problem that requires further evaluation.

---

The Broader Value of Good Indoor Air Quality

Preventing summer mold is only one part of an effective indoor air quality program.

Good IAQ management supports healthier, more comfortable, and more functional learning environments throughout the year.

Poor indoor environmental conditions may contribute to respiratory irritation, allergies, asthma symptoms, headaches, odors, and occupant discomfort. They can also lead to complaints, absenteeism, maintenance problems, and damage to building materials.

A proactive IAQ program can help districts:

• Reduce emergency remediation costs
• Protect school buildings and furnishings
• Identify recurring moisture problems
• Improve planning and maintenance
• Minimize classroom disruption
• Support student and staff comfort
• Prepare facilities for the first day of school

It can also provide valuable documentation showing that the district is actively monitoring and maintaining indoor environmental conditions.

---

How Hillmann Can Help

For over 40 years, Hillmann has helped school districts, educational institutions, municipalities, facility managers, and building owners evaluate and address indoor environmental concerns.

Our Environmental Health & Safety and Building Sciences professionals provide practical, science-based support tailored to each facility’s conditions and operational needs.

Hillmann’s capabilities include:

• Indoor air quality assessments
• Mold and moisture investigations
• Temperature and relative humidity monitoring
• Moisture intrusion evaluations
• HVAC and ventilation evaluations
• Mold remediation protocols
• Remediation oversight and clearance services
• Building-envelope evaluations
• Proactive IAQ program development
• Quarterly and biannual IAQ assessments

Our team works to identify the source of an indoor environmental concern, explain the findings in the proper context, and recommend practical corrective actions.

A proactive indoor air quality program can help school districts reduce costs, protect building assets, minimize disruption, and ensure facilities are ready when students and staff return.

Preparing your schools for the upcoming academic year? Contact Hillmann to discuss a proactive indoor air quality assessment or an ongoing IAQ program for your district.

---

Frequently Asked Questions

Why do schools develop mold during summer break?

Schools may experience elevated indoor temperatures and humidity when HVAC systems operate on reduced schedules. Warm outdoor air, leaks, wet cleaning activities, and insufficient dehumidification can all contribute to mold growth.

Can mold grow without a major leak?

Yes. Elevated indoor humidity, condensation, and damp building materials can support mold growth even when there is no obvious roof or plumbing leak.

How often should schools conduct IAQ assessments?

The appropriate schedule depends on the building, climate, history, and operating conditions. Quarterly or biannual evaluations may be helpful for districts seeking a proactive approach.

Is mold testing always required?

A thorough assessment typically begins with a visual inspection, moisture evaluation, and review of HVAC and building conditions. Sampling may be recommended when it can answer a specific question or help define the extent of a concern.

Learn More: Explore Hillmann’s Indoor Air Quality and Building Sciences services to see how our team helps schools proactively manage indoor environmental conditions.

---

Additional Resources

• EPA IAQ Tools for Schools – Practical guidance for developing and maintaining effective indoor air quality programs in K-12 schools.
• EPA Mold Resources – Information on preventing, identifying, and responding to mold and moisture issues in educational facilities.