Based on our over 500 proactive school IAQ walkthrough assessments – and numerous technical site visits in response to concerns – mold is still a major IAQ issue for schools. We estimate mold was either the primary, or one of the top, issues of concern in our site problem investigations. This is true for both old and new schools.
The recipe for mold is “just add water,” so of course buildings located in wet climates experience more challenges. But all regions have precipitation and we find that buildings in drier climates sometimes aren’t as water-resistant as those located in high moisture areas. And of course all schools have plumbing (at least we hope so).
It’s the Moisture
Unfortunately, the majority of schools we visit have water leaks. Most of these leaks are from design and construction deficiencies and deferred maintenance practices. Flat roofs, lack of sufficient overhangs, walls and windows that leak, schools built in wetlands, slab-on-grade concrete floors without moisture controls, and downspouts routed through the interior of buildings are all examples of pushing our luck on design versus performance. In addition to rain and snow melt infiltration and plumbing leaks, condensation on cool indoor surfaces (below "dew point") from high relative humidity is an issue we need to keep in mind when checking around our buildings.
Prevention Pays
It costs significantly more to fix problems than to prevent them in the first place. Fixing occupant perceptions and restoring trust is often even more difficult! Prevention of moisture problems is relatively simple:
1. Routine inspection of the building’s drainage planes
a. Roof and flashings
b. Gutters and downspouts
c. Siding, windows, doors, other joints and penetrations
d. Site drainage
e. Irrigation and sprinkler systems
f. Concrete slab-on-grade floors
2. Routine monitoring of indoor water sources
a. Restrooms
b. Classroom plumbing (especially elementary schools, art, science)
c. Locker rooms
d. Kitchen
e. Custodial
f. Water fountains
3. Ventilation with outside air to control indoor relative humidity levels
a. Flushing buildings with the recommended amount of outside air removes moisture (the cooler the outside air, the more the drying effect; see side panel, “Ventilating With Cool Outside Air”).
b. Ensure exhaust fans are functioning properly and are effective in capturing and removing moisture before it spreads to other parts of the building.
4. Monitor indoor relative humidity levels and cold surfaces
a. Check for high moisture levels and eliminate the moisture source
b. Check surface temperatures and compare to the “dew point” temperature. Solutions include adding insulation to keep the surface warm, lower the relative humidity, or replace the surface material with mold resistant product (foam, masonry, plastic, metal, rubber, etc.)
Are You Sure It's Mold?
The best way to conduct a mold investigation is with visual inspection, aided by the use of tools. Don’t be afraid to use invasive techniques to rule-in or rule-out the existence of moisture or molds in building cavities. Invasive measures include cutting holes, removing baseboards, looking behind sidings and window casements, etc. Careful and thorough inspections are necessary to determine first if there is a problem and second the cause and extent of any contamination. The thorough inspection also leads to a permanent solution of the moisture problem, and adequate cleanup of molds.
If the moisture problem can’t be solved immediately – and there are plenty of reasons why this is often not easy, affordable, or practical (e.g., three feet of snow on a roof) – then at least the mold food can be removed to eliminate/reduce future mold growth until the moisture problem is fixed. Wet materials aren’t the problem, but wet mold foods are!
Every mold problem is a contamination problem. Schools need to first decide whether the problem is to be handled in-house or in conjunction with an outside contractor. Both approaches need a well-thought-out plan of action. The plan should include a communications component at all phases.
Get Outfitted
OK, we know facilities and custodial staff are sometimes over-worked as it is. We need to provide these professionals with diagnostic equipment for them to work smarter not harder. Here are the tools needed:
- Moisture meters: pin-type and contact-type (approx. $200-$300)
- Laser surface temperature meter (less than $100)
- Digital relative humidity and dew point meter (less than $100)
- Infrared camera – excellent tool but expensive. Saves time and is very useful for other tasks such as energy savings, electrical problems, water savings, etc. ($3,000 and up)
How Much Mold Can We Handle Ourselves?
Follow the Environmental Protection Agency (EPA)'s or other equivalent methods of remediating mold. The publication Mold Remediation in Schools and Commercial Buildings is available at www.epa.gov/ mold/mold_remediation.html or call 1-800-438-4318 to request a free copy.
Table 2 in the mold publication offers the following EPA “Guidelines for Remediating Building Materials with Mold Growth Caused by Clean Water”:
SMALL - Total Surface Area Affected Less Than 10 square feet.
• Minimum Personal Protective Equipment (PPE) - N-95 respirator, gloves, goggles
• No containment required
MEDIUM - Total Surface Area Affected Between 10 and 100 square feet.
• PPE - limited or full - N-95 respirator, gloves, goggles, coveralls
• Limited containment - polyethylene sheeting, HEPA filtered negative-air fan, block supply and return ducts
LARGE - Total Surface Area Affected Greater Than 100 square feet (or potential for increased occupant or remediator exposure estimated to be significant)
• Full PPE - full body clothing, head gear, foot coverings, full-face respirator with HEPA filter
• Full containment - two layers fire-retardant polyethylene sheeting, air lock chamber plus HEPA negative-air fan, block HVAC vents
Respond to Fungal Problems
IDENTIFY
• Extent of moisture damage and contamination
• Dynamics of moisture sources
• Appropriate containment and worker protection
DRY wet areas in the short term. Use heat to evaporate the moisture and exhaust ventilation to remove this moisture-laden air. Dehumidifiers may be needed. Be sure to contain the work zone! And direct the exhaust to a safe outdoor location.
DESIGN
• Long-term intervention to address the moisture dynamics
• Fungal clean-up procedures and clearance criteria
DISCARD - DECONTAMINATE contaminated material
• Poly BAGS
• Dispose as regular construction waste
IMPLEMENT repairs and program changes to prevent future problems.
VERIFY that the work was complete, the containment adequate, and the space thoroughly cleaned.
The first consideration is to protect occupants, workers, and contain the mold contamination – and prevent future exposures. Unless it’s a minor (10 square feet) area, treat the job like an asbestos job – careful containment, personal protection equipment, negative air, thorough disposal and final cleanup.
Make absolutely sure you know the cause of the mold growth and institute a permanent fix – if not, remove mold food from the source of moisture. Contain, capture, re-direct the moisture or water entry until a permanent fix can be provided. Again, keep mold food away from the moisture and maintain a careful watch on the situation.
Remember, even dead and dormant molds pose an exposure issue. Dry molds are easily dispersed into the air. So, don’t just dry moldy materials, but promptly clean or discard them while they are still wet to avoid increasing exposures due to airborne molds.
Cleaning molds doesn’t mean killing molds. Cleaning basically means getting the mold out of the building safely. Think about containment of the work area, personal protection for the cleaning crew, and the proper cleaning equipment and supplies.
Most guidance does not recommend bleach as a cleaning agent. Bleach kills molds, but is not an effective cleaning agent. Use a dilute solution of biocide and detergent. The goal is removal and cleaning, not killing the molds. “Clean-enough-to-eat-off-of” is a good rule to follow. Detergent is generally sufficient to clean surfaces.
If the mold is consuming gypsum wall board, ceiling tiles, and other “paper” products, it’s generally best to discard these materials. Valuable books and papers can sometimes be rescued by freeze-drying and HEPA vacuuming. Solid lumber and other materials with surface mold can generally be salvaged. Start with a HEPA vacuum followed by thorough scrubbing. Moisture can compromise the structural integrity of particle board, plywood, oriented strand board and other such materials – get professional advice on whether to salvage or replace.
You want to put the issue to bed once and for all – don’t leave any skeletons in the closet or invite second-guessing. Do the remediation once and do it right. Again, your best investment is in prevention.
Communicate
Always keep occupants informed of your approach, timelines, and quality assurance measures to alleviate any misunderstandings, skepticism, or rumors. If, for whatever reason, your credibility is in question, involve concerned staff in the decision making and protocols and monitoring of the process to ensure satisfaction. Invite inspections and other participation by skeptics. Offer to show them the area after cleaning and before renovation to satisfy their need to know (or curiosity) that all contamination has been addressed. Get expert help when needed, and since water management can be as much an art as a science, don’t be afraid to seek more than one opinion.
Again, follow EPA or other equivalent methods of remediating mold. EPA’s Mold Remediation in Schools and Commercial Buildings is available at www.epa.gov/moldmold_remediation.html or call 1-800-438-4318 to request a free copy.
Source: IAQ News
© 2010 Washington State University Extension Energy Program
