Mold's Relationship to Roof Maintenance

by Curtis Liscum, RRC

Are you beginning to think that mold really is a four-letter word?  Many building owners are starting to comprehend the potential ramifications of how mold affects indoor air quality (IAQ).  These ramifications can manifest themselves as damage to building materials, degraded IAQ, sick building symptoms and potential lawsuits.  

Mold commonly occurs in most households. Remember that bread that was left too long in the bread drawer?  Mold even exists in most organic building materials.  We commonly see Lichens (mold) growing on the top exterior surface of roofs, within wet organic roof insulation boards, and on wet wood nailers.  Interestingly enough, we also have seen it on both treated and non-treated materials.  The one thing that all these have in common, is that they are on surfaces that 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, providing that temperature and moisture conditions are within supportive limits.  Typical materials include ceiling tiles, gypsum board, wallpaper, insulations, adhesives, wood trim and wood framing materials.  These materials have been used for years in construction, many never experiencing mold growth.  So what is the catalyst - temperature or moisture?  Temperature seems to be unlikely as many similar building types have like interior environments and some have mold, some not.  It appears that moisture may be the single most probable catalyst to affect mold growth.  This seems likely as most observed mold growth is associated with leaks/condensation probelms in roofs, windows or walls.  Studies have proven that leaks in a building can contribute to mold growth within as little as 24 to 48 hours.  

Mold has been observed in ceiling tiles at areas of repeated roof leaks or areas where a lack of insulation creates condensation drips.  Mold can spread in gypsum board behind vinyl wallpaper where roof/window/wall leaks or condensation creates a moist environment and the vinyl wallpaper prevents the moisture from drying out into the interior of a room.  

If roof leaks are a major contributor to mold development, then keeping water out of organic building materials is paramount to preventing mold evolution.  An aggressive leak response program must be established.  Leaks must be investigated, origin points determined and deficiencies remediated in a timely manner or mold infestation is assuredly the expected outcome.  Leaks must be stopped within 24 to 48 hours and the wet materials dried out or mold growth is possible.

As important as leak response is, it is nonetheless reactive, and materials get wet prior to identifying the problem.  An improved approach would be to develop and preserve an aggressive roof maintenance program.  This program should include the following:  

Every roof should be periodically inspected to identify deficiencies.  It is preferable to perform these inspections in the spring and fall each year.  Individuals capable of determining not only apparent immediate problems but also those conditions that could become problems, must perform these inspections.  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, reviews should also be accomplished after severe storms, repair or alterations to the rooftop equipment or reroofing of adjacent roof areas.

Once the deficiencies have been identified, a qualified roofing mechanic must perform repairs in a timely manner.

A properly executed roof maintenance program should not only reduce leaks, thereby minimizing mold development, but as a secondary benefit it should increase roof longevity.

If you suspect mold has infested a building material, a visual inspection is the most important step in identifying a possible mold contamination problem.  The extent of water damage and mold growth should be visually assessed, and all organic materials should be investigated.

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.  Remedial strategies can usually be made on the basis of a visual inspection.

When investigating for mold it is important to following the following safety tips:

1.   Do not touch mold or moldy items with your bare hands

2.   Do not get mold or mold spores in your eyes

3.   Do not breathe in mold or mold spores

Consider using appropriate Personnel Protective Equipment (PPE).  The minimum PPE should be a respirator, gloves and eye protection.

Once the extent of mold is determined by visual assessment, remediation is the next chapter in the saga.  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 done using a detergent cleaner.

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

It appears that mold growth and roof leaks are directly related.  That being the case, annual roof maintenance may be the first line of defense against mold development.  If leaks do exist, they must be investigated and repaired immediately.  To stop mold development, we must take the position that roof leaks are not acceptable and that they must not be tolerated.  An aggressive preventive maintenance program should not only provide tangible results in mold prevention, but should go a long way in improving public relations as a concerned building owner.