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What Causes Mold in a Daycare or Preschool Building?

Last updated October 23, 2026

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The short answer

Common Sources of Water Leaks

Leaking pipes behind walls or under sinks are a frequent source of hidden moisture in these buildings. Roof leaks, especially around flat sections or skylights, can allow water to seep into ceilings and insulation over time. Windows that do not seal properly may let in rain, and damaged exterior siding can lead to wall cavities getting wet during wet weather.

Even small, slow leaks from drinking fountains, sinks, or toilet supply lines can cause significant damage if they go unnoticed. These leaks often occur in cabinets or utility closets where they are not immediately visible. The persistent dampness from such a leak provides the continuous moisture mold needs to colonize building materials within days.

High Humidity from Daily Activities

The daily routine in a childcare center naturally generates a lot of moisture. Frequent handwashing, art projects with water, and cleaning activities all release water vapor into the air. Cooking and dishwashing in a kitchen area add more humidity. If this moist air is not properly exhausted, it condenses on cooler surfaces like windows and exterior walls.

Inadequate ventilation is a major contributor. Many older buildings have ventilation systems that cannot handle the high occupant load and activity level of a preschool. When warm, humid indoor air meets a cold surface, condensation forms. This constant dampness on walls, ceilings, and inside wall cavities creates an ideal breeding ground for mold without any visible leak.

  • Frequent handwashing at multiple sinks.
  • Steam from kitchen cooking and dishwashing.
  • Damp mops and towels drying in utility rooms.
  • Humidity from many children breathing and playing.
  • Water play tables and art activities.
  • Wet clothing and boots stored indoors.

Poor Building Maintenance Issues

Deferred maintenance allows small problems to become big mold issues. Cracked caulk around windows and doors, damaged roof flashing, and clogged gutters or downspouts can direct water into the building envelope. In historic buildings, original single-pane windows and older plumbing are particularly susceptible to failures that introduce moisture.

Worn-out sealant in showers or around drinking fountains can let water seep into walls. Failing HVAC systems may not dehumidify the air properly, and dirty air filters can restrict airflow, leading to condensation inside ducts. Regular inspections of the roof, plumbing, and building exterior are crucial to catch issues before they lead to mold growth.

Responding to Spills and Floods

Accidents like a major toilet overflow, a sink left running, or a broken water line can flood a classroom quickly. If the water is not extracted and the area dried thoroughly and rapidly, mold can begin to grow within 24 to 48 hours. Water can wick up drywall and soak into subfloors, creating hidden pockets of moisture.

Carpet cleaning with too much moisture or improper drying can also cause problems. If a large area rug or classroom carpet gets soaked and is not dried completely from the padding up, mold will grow underneath. The key is immediate water extraction followed by structural drying to remove all residual moisture from the affected materials.

How to Identify a Potential Problem

A musty odor is often the first sign of hidden mold, even when no visible growth is present. Look for water stains on ceilings, walls, or around windows. Peeling paint or wallpaper, warping baseboards, and a general feeling of dampness in a room are all indicators of a moisture issue that could lead to mold.

Check areas where moisture is common, like under sinks, around toilets, and in storage closets that share walls with bathrooms. Inspect ceiling tiles for discoloration, which can signal a roof leak above. If you find any signs of water damage or persistent dampness, it is important to address the source and dry the area completely to prevent mold.

  • A persistent musty or earthy smell in a room.
  • Discolored patches or staining on walls or ceilings.
  • Paint that is bubbling, cracking, or peeling.
  • Warped or buckling floorboards or baseboards.
  • Condensation constantly forming on windows or pipes.
  • Visible fuzzy or speckled growth on surfaces.

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Frequently asked questions

Is mold in a daycare dangerous for children?

Mold can cause health reactions, especially in young children who may have allergies or asthma. Common symptoms include coughing, wheezing, or itchy eyes. If mold is suspected, it is a health and safety priority to have it assessed and properly remediated by qualified mold professionals.

Who is responsible for fixing mold in a leased space?

Responsibility depends on the lease and the source of the moisture. The landlord typically handles structural issues like roof leaks, while a tenant may be responsible for plumbing fixtures they control. Review your lease agreement and communicate promptly with the property owner about any water damage.

What should I do if I discover a water leak?

Stop the water source if it is safe to do so, like shutting off a valve. Remove any valuables or porous items from the water. Contact local water damage pros for water extraction. The faster the water is removed and drying begins, the lower the chance for mold to develop.

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