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By Curtis Liscum
January 2004 -
Roofing Article Use Policy
Many maintenance and engineering managers have begun to fully comprehend the potential ramifications of mold for indoor air quality (IAQ). These ramifications can manifest themselves as damaged building materials, degraded IAQ, sick building symptoms, and potential lawsuits.
Mold commonly occurs in most organic building materials. It is common to see lichens, or mold, growing on the top exterior surface of roofs, within wet organic roof insulation boards, and on wet wood nailers, interestingly enough on both treated and non-treated materials. The one thing that all these surfaces have in common is that they are are above the roof deck and, therefore, have minimal impact on IAQ.
When mold growth develops on interior surfaces, IAQ can be affected and building occupants start asking questions. Most organic building materials can support mold growth if temperature and moisture conditions are within supportive limits. Typical materials include ceiling tiles, gypsum board, wallpaper, insulation, adhesives, wood trim and wood framing materials. These materials have been used for years in construction, many never experiencing mold growth.
What is the catalyst for mold growth: temperature or moisture? Temperature seems to be unlikely, as many similar building types have similar interior environments, and some have mold, while others do not. It appears that moisture might be the single most probable catalyst to affect mold growth. This seems likely as most observed mold growth is associated with leaks and condensation problems in roofs, windows or walls. Studies have proven that leaks in a building can contribute to mold growth within as little as 48 hours.
Mold has been observed in ceiling tiles near repeated roof leaks or where a lack of insulation creates condensation. Mold can spread in gypsum board behind vinyl wallpaper where roof, window and wall leaks or condensation create a moist environment.
The vinyl wallpaper prevents moisture from drying out. Moisture in “paper” wallpaper, organic adhesives, insulation materials and wood products also provides a delectable environment for mold development.
The obvious first step in any manager’s effort to prevent roof leaks — and mold growth — is proper installation of the original system. Beyond that, if roof leaks are a major contributor to mold development, then keeping water out of organic building materials is paramount to preventing mold growth. Managers must establish an aggressive leak response program. Technicians must investigate leaks, determine origin points and address deficiencies in a timely manner. Otherwise, old infestation is assuredly the expected outcome. Leaks must be stopped within 48 hours and the wet materials dried out, or mold growth is possible.
Leak response, though important, is reactive, and materials often get wet before a problem can be identified. A better approach would be to develop and preserve an aggressive roof-maintenance program. This program would include the following steps:
Periodically inspect every roof to identify deficiencies. It is best to perform these inspections in each spring and fall. Inspections should be performed by individuals capable of determining not only apparent immediate problems but also conditions that could become problems in the near future. The inspections should concentrate on high-risk areas such as around roof hatches, drains, mechanical equipment and high-traffic areas.
In addition to semi-annual inspections, perform inspections after severe storms, repair or alterations to rooftop equipment, or reroofing projects in adjacent roof areas.Perform repairs in a timely manner. Once inspectors have identified deficiencies, a qualified roofing mechanic must make the repairs. A properly executed roof maintenance program should not only reduce leaks — and minimize mold development — but also should increase roof longevity.If managers suspect mold has infested a building material, a visual inspection is the primary and most important step in identifying a possible mold-contamination problem. Inspectors should visually assess the extent of water damage and mold growth and investigate all organic materials.The inspectors also should take extreme care and diligence to thoroughly investigate hidden and hard-to-see surfaces. They should use moisture meters to determine excessive moisture contents that could promote fungal growth. Bulk sampling generally is not required unless there is a need to identify a specific fungal type. Managers then can develop remedial strategies on the basis of the visual inspection.Safety firstWhen investigating for mold, it is important for workers to adhere to these safety tips:
Once visual assessment determines the extent of mold, remediation is the next step. The goal 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 materials, such as metal decks, and semi-porous materials, such as wood or concrete, that are structurally sound can be cleaned with a detergent. Porous materials such as wallpaper, insulation, acoustical or fireproofing materials, gypsum boards and ceiling tiles generally require removal and disposal.Clean-up considerationsRemediation procedures depend on the building occupancy, the area of contamination, the material to remediate and the size of the area affected. Typical procedures are include these:
It appears that mold growth and roof leaks are directly related. As a result, annual roof maintenance might be the first line of defense against mold development.If leaks exist, they must be investigated and repaired immediately. To stop mold development, managers must take the position that roof leaks are not acceptable and that they must not be tolerated. An aggressive preventive maintenance program not only should provide tangible results in mold prevention but should go along way in improving public relations.
If a roofing project is begins during cold weather, it is important to realize that weather affects most roof-system installations. Managers should consider these points for cold-weather roofing application.
Most materials used in any roof system are affected by cold weather. Left unprotected, they can get wet or too cold. Installing them if they are wet or before they have arrived at the proper temperature is likely to create problems with blisters or wrinkles. This is particularly problematic for materials such as SBS-modified bitumen that needs to “relax” before installation.
Many membrane and insulation adhesives can only be installed when the ambient air temperature is 40 degrees and rising. They also must be kept at acceptable temperatures during storage. If the adhesives are installed below these temperatures or are allowed to freeze, they might never achieve proper adhesion.
Several adhesive manufacturers restrict shipment of water-based products to the snow belt during the winter months. If a project is specified with these adhesives, they might be unavailable when work begins. This could require delaying the project or using alternative adhesives that might have objectionable odors or fumes.
Managers can mitigate several of these limitations with proper planning, such as temporary heated storage. Understanding the cold-weather limitations of the roof system and discussing the options before undertaking the project will help parties make informed decisions that help complete the project successfully.
— By Derek Josephson, a staff consultant with Benchmark Inc. in Cedar Rapids, Iowa