In a recent study of 90 buildings investigated by the University of Nevada, Las Vegas (UNLV), it was determined that more than a third of them had significant mold growth. This article will discuss current thoughts as it relates to the identification and remediation of mold in roofing systems.

Molds are a group of organisms that belong to the kingdom Fungi. There are over 20,000 species of mold identified in the world today. Molds can grow on virtually any organic substance, providing moisture and oxygen are present. Molds require water to grow.

A visual inspection is the primary and most important step in identifying a possible mold contamination problem. The extent of water damage and mold growth should be visually assessed. All organic material should be investigated such as roofing membranes, insulations, base sheets, organic deck materials, spray-applied acoustical / fireproofing materials, gypsum boards, ceiling tiles, and ventilation ductwork and filters.

Extreme care and diligence should be exercised to ensure that hidden and hard to see surfaces are thoroughly investigated. Moisture meters should be utilized to determine excessive moisture contents that would possibly promote fungal growth.

Bulk sampling is generally not required unless identification of a specific fungal type is desired. Air sampling is again not generally required. Remedial strategies can usually be made on the basis of a visual inspection. Reports have indicated that air monitoring for some fungi are prone to false negative results and therefore may not be conclusive in ruling out contamination.

Individuals trained in the proper sampling methods for microbial contaminates should obtain air and bulk samples. In addition, trained personnel from laboratories accredited by the American Industrial Hygiene Association (AIHA) should conduct microscopic identification of spores.

When investigating for mold it is important that you follow the following safety tips:

• Do not touch mold with your bare hands 
• Do not get mold or mold spores in your eyes 
• Do not breathe in mold or mold spores

The goal of remediation is to remove or clean contaminated materials in a way that prevents fungi and dust contamination from leaving the work area and entering an occupied or non-abatement area, while protecting the health of the abatement workers.

Non-porous (metal decks) and semi-porous (wood and concrete) materials that are structurally sound can usually be cleaned. Cleaning is usually done using a detergent cleaner.

Porous materials such as roofing membranes, insulation, acoustical / fireproofing, gypsum boards and ceiling tiles generally require removal and disposal.

Most information reviewed rejects the use of gaseous ozone or chlorine dioxide for remedial purposes. Both compounds are highly toxic and may pose a health threat to civilians and abatement workers.

Remediation procedures depend on the building occupancy, area or contamination, material to be remediated and the size of the affected area.

• The water entry point has been repaired

• The mold is completely removed

• Periodic revisits indicate no new mold growth

• Occupants experience no related health complaints or physical symptoms

The key to mold control is moisture control. A few mold prevention tips are as follows:

Fix roof leaks as soon as possible.

Watch for condensation and wet spots. Repair sources of moisture as soon as possible.

Prevent moisture due to condensation by installing vapor retarders, adequate insulation and adequate ventilation.

Maintain indoor relative humidity below 60%, ideally 30% - 50%, if possible.

Vent moisture-generating equipment to the outside where possible.

Clean, dry or remove wet material within 48 hours.

In all cases, the underlying cause of moisture intrusion must be stopped or fungal growth can occur. Evidence indicates that if water infiltration is not stopped, dried out and / or removed within 24-48 hours, organic material can support fungal growth. If the source of the water is elevated humidity, relative humidity levels should be maintained below 60% to inhibit mold growth. Emphasis must be placed on preventing, controlling and stopping roof leaks if we are to control fungal contamination and manage indoor environments appropriately.