Related resources

Related resources

Related resources

Mold control on the job site

Molds are naturally occurring substances that are found everywhere. Excessive mold growth can be detrimental to a building or its inhabitants. Some molds can deteriorate woods or other organic materials, while other molds may cause or contribute to adverse health effects. For those people who are affected by mold exposures, there can be a wide variation in how they react. People at greatest risk of health effects are individuals with allergies, asthma, sinusitis or other respiratory conditions. Health issues associated with mold exposure typically include runny nose and eye irritation.

Mold grows in conditions of moisture, darkness and stagnant air. Mold growth results in the release of millions of spores that may be inhaled by workers. Moisture control is the critical step for controlling mold growth. Moisture control in buildings requires cooperation between owners, designers, contractors and occupants.

During construction, contractors can affect the presence of building moisture and should not allow sources of moisture to affect the materials and structure at the job site. Contractors who use poor workmanship may negate design features that are intended to control moisture. This page highlights steps to take to prevent conditions that promote mold growth.

Site management

  • Inspect all shipments of construction materials for visible mold or excessive moisture.
  • Do not unload lumber or other moisture-sensitive materials in the rain, unless protected from exposure.
  • Schedule deliveries to minimize the amount of time moisture-sensitive materials are stored on site.
  • Store materials off the ground and away from sources of moisture.
  • Loosely cover materials with plastic sheets or tarps to protect the materials from rain or snow.
  • Anchor material covering from the top and keep the cover materials away from the sides and bottoms to promote air circulation and decrease moisture retention.

Construction practices

  • Protect building interiors from prolonged rain and snow exposures.
  • When framing lumber has been exposed to rain or snow, allow it to dry out before enclosing the structure.
  • Clean and treat visible mold growth before wood products are sealed.
  • Check building water services for leaks and improper installation.
  • Provide ventilation to remove moisture from buildings during construction.
  • Provide proper ventilation in attic and crawl spaces.
  • Ensure that all stove vents, dryer vents and other spot ventilation exhaust to the outside.
  • Ensure that all building penetrations, intersections and openings are properly flashed to prevent leaks.
  • Ensure that building sealants are compatible with adjacent building materials.
  • Seal any tears, openings or punctures that are found in vapor diffusion retarders and air barriers before covering with other materials.
  • Drain downspouts away from the foundation.
  • Ensure that building siding does not come in contact with ground surfaces.

Work practices

  • Do not eat, drink or smoke in work areas.
  • Avoid breathing dusts.
  • After an area has been cleaned and is completely dry, vacuum the area with a HEPA vacuum. HEPA vacuums are also recommended for cleaning up dust that may have settled on surfaces outside the work area.
  • After working, wash thoroughly, including hair, scalp and nails.

Additional information is available at Occupational Safety and Health Administration (OSHA)'s Safety and Health Topics webpage on mold.

Copyright ©2020, ISO Services Properties, Inc.

This material is provided for informational purposes only and does not provide any coverage or guarantee loss prevention. The examples in this material are provided as hypothetical and for illustration purposes only. The Hanover Insurance Company and its affiliates and subsidiaries (“The Hanover”) specifically disclaim any warranty or representation that acceptance of any recommendations contained herein will make any premises, or operation safe or in compliance with any law or regulation. By providing this information to you. The Hanover does not assume (and specifically disclaims) any duty, undertaking or responsibility to you. The decision to accept or implement any recommendation(s) or advice contained in this material must be made by you.

LC NOV 2018 10-268 H
171-0974 (12/18)