FM Frequency: Elementary, My Dear Watson (Part 2)
By Jeff Crane, P.E., LEED® AP
Published in the December 2008 issue of Today's Facility Manager
October's FM Frequency column "Elementary, My Dear Watson (Part 1)" asserted that facility managers (fms) are often detectives—gathering facts, asking questions, and conducting thorough investigations while solving complex riddles. The article introduced an intriguing mold investigation, offering 10 brief facts about a small rental cottage with visible mold spores on the interior ceiling.
In the article, readers were invited to offer advice and suggestions or submit additional questions to Watson, our investigator, in his quest to solve the mold problem. The October column concluded with Watson approaching the cottage in question for the first time, armed with only those few facts.
Let's resume the investigation, aided by these suggestions from readers:
- Scott Sisemore (facilities supervisor with Central United Methodist Church) observed that since the mold spores were on the ceiling, Watson should inspect the attic space and confirm it's properly insulated. If batt or blanket type insulation was used, the vapor barrier should face down (toward the occupied space); but if the insulation was blown in place, Watson should check for gaps or air pockets that could have resulted from settling. He was one of many contributors suspicious of the attic ventilation.
- Jason Meeks felt the mold culprit might be elevated humidity levels inside the cottage, due to its proximity to the ocean and the intermittent use of air conditioning. One solution Meeks offered was to air condition the building continuously, even when it's not in use.
- Scott Fleury (facilities manager with the City of Marquette, MI) was another contributor who wanted Watson to check attic ventilation and insulation. He suggested looking for signs of rodents or bats in the attic and mentioned reviewing construction reports for evidence of unusual rain incursions that may have occurred before the roof was completed.
- Frank Harrison (architect) again suggested confirming proper attic ventilation and consistent HVAC operation. He also asked if curtains or drapes were covering the windows and suggested checking to see if moisture might be migrating from the attic space through the finished ceiling and condensing on the inside. Harrison next prompted Watson to check the crawl space to see if it was ventilated and protected with at least a 10 mil thick vapor barrier covering the ground (under the cottage).
- Terry Harp (building and zoning director, Village of Swansea, IL) not only suggested inspecting the crawl space to confirm proper ventilation and vapor barrier (with 6" overlapped seams) on the ground, he also mentioned checking the relative humidity in the space (and looking for mold spores on the floor joists). In a new twist, Harp wanted Watson to search for evidence of cracking from expansion and contraction around the stone chimney and to inspect the flashing where the stone chimney mates with the metal roof (which should also be checked for condensation on its underside). Harp was another one who suspected the attic ventilation/insulation.
- Bill Parker (facilities coordinator with Windermere Cronin & Caplan Realty) wanted Watson to inspect the heating/cooling units and any uninsulated water lines in the attic. Like Harp, Parker wanted Watson to inspect the metal roof's connection to the trusses and look for evidence of any condensation or slow drips/leaks that could cause high moisture levels in the attic's insulation and ceiling materials.
- Thomas Brekke (director of facilities, Campus of St. Scholastica) suggested investigating the kitchen and bathroom exhaust to see if warm, moist air from cooking or showers was being properly removed from the space. He also suggested using a meter to check the moisture content of walls and ceiling areas. Brekke was suspicious of the attic ventilation as well.
- Tom Giacobassi, RPA, FMA, SMA (manager, Metro Region of Blue Cross Blue Shield of Michigan and Blue Care Network of Michigan) used his powers of deduction to head straight for the attic. Several trapped moisture culprits were mentioned in his report to Watson, and he suggested a thorough investigation and humidity monitoring to help determine what moisture levels were present. He also wanted to track weather conditions to see if they could be be adding to the problem.
- John M. Edwards (director of office services, Perkins Coie LLP) was another contributor who asked if insulation was installed so the vapor barrier was on the attic side. He was also suspicious of the ventilation in the crawl space and attic. Other possible areas of investigation for Edwards were the bathroom and kitchen—undeniable sources of moisture buildup if not properly ventilated. Checking for minimum operating standards for the mechanical systems was another strategy from Edwards.
- Mark Oldham (a seasoned IAQ investigator) contributed some extensive additional feedback regarding placement of the air conditioner condenser. He suggested measuring relative humidity (RH) at different elevations in the cottage and guessed that occupants kept doors and windows open while the air conditioning was operating, thus allowing the warmer outside air to collect in the vaulted ceilings and then get cooled there. Since massive amounts of mold spores are already present in the outside air, they're more than happy to feed on the pre-finished wood paneling. His conclusion: "Basically, the unit has weather. Not enough to generate clouds and rain, but enough to create a moisture problem."
- Chris Grawburg, P.E. (The HVAC Training Institute, Inc., Raleigh, NC) wanted Watson to verify wall and roof insulation (including correct installation of the vapor barrier) and asked him to check for leaks around windows and doors. Grawburg was the only investigator to mention the fact that some high end homes have dedicated outside air brought to their HVAC units. He pointed out that some municipalities require a damper on the outside air to close when the air handler unit is not running; if this damper is not there, fans will suck in humidity.
A few other anonymous "virtual detective" tips for Watson included:
- Inspect all plumbing lines, connections, and drains in the crawl space, especially under the bathroom and kitchen. Look for evidence of current or past leaks and related moisture and mold.
- Check gutters, downspouts, and proximity of trees to the building. Clogged and overflowing gutters can result in damaged soffits, walls, floors, and mold.
- See if there is heavy vinyl wallpaper in the cottage. Certain types are not permeable and can act as an unintentional vapor barrier, trapping moisture between interior and exterior walls. This moisture can amplify over time and cause serious mold outbreaks.
- When in the attic, look for rust or calcium streaks, which may indicate slow leaks in the metal roof.
- Check for standing water in the crawl space or evidence of improper storm drainage around the foundation. Moisture can travel into the conditioned space above, especially when the fireplace is used and the cottage is under negative pressure.
- Inspect doors, windows, and any other penetrations to the building envelope. Look for evidence of rotting window sills and door frames. Make sure any wall penetrations for electrical wires, refrigeration pipes, etc. are properly sealed.
- Confirm temperature, humidity, and dew points in the building, attic, and crawl space. See if the temperature and dew point within a few inches of the ceiling is very different from conditions at the thermostat.
- Check the size of the air conditioning system and the location of the thermostat and supply/return grills. An oversized air conditioner could be cycling on and off too quickly for proper dehumidification. Also, if the evaporator is in the attic, see if it has a clogged or sweating condensate line dropping moisture on the attic insulation and ceiling materials.
- Use a moisture meter to inspect walls and floors around showers, sinks, toilets, refrigerator, and washing machine connections. Look for water marks or staining that could indicate current or former leaks.
- These are all excellent suggestions from a variety of facility sleuths with decades of combined experience. Now let's compare them to Watson's site visit notes, observations, and recommendations for the cottage owner. As with many mold problems, we probably won't be shocked to find multiple "smoking guns."
- No indications of roof leaks or problems with chimney flashing or stone work.
- Adequate blanket insulation properly installed with vapor barrier facing down (toward living space).
- Insulation and attic are dry. No indications of roof or plumbing leaks.
- Electric attic exhaust fan in the west gable is controlled by thermostat in attic, but fan motor is locked up. Owner has no idea how long it has been out of service.
Recommendation. Disconnect broken attic exhaust fan, and cut a ridge vent into the roof. This would be more reliable than powered exhaust and requires no electricity.
- Many mature trees grow close to cottage, and gutters are full of leaves and pine needles. Minor soffit damage is evident behind dysfunctional gutters, but moisture meter detects no damage to exterior siding or interior walls. However, two windows sills (south facing wall) are beginning to show paint/caulk failure and water intrusion.
Recommendation. Clean gutters, repair/replace/repaint damaged soffits and window sills. Consider capping system allowing water (but not debris) to enter gutters. Regularly inspect gutters or remove them from cottage.
- Single 3.5 ton heat pump (split system with emergency electric heat) with air handler/evaporator in attic cools and heats cottage. Return air filter and condensate trap are relatively clean. HVAC unit appears to be in excellent condition and cycles on and off when thermostat is manually activated.
Recommendation. See note about interior conditions and heat pump size.
Crawl Space Inspection
- Found puddles of standing water (possibly caused by improper rain diversion away from the building), inadequate plastic vapor barrier on the ground, high moisture levels, and mold spores on the floor joists.
Recommendation. Install appropriate vapor barrier over ground in the crawl space and adjust property's grading to divert rain around foundation. If that's impossible, consider installing a gravel trench and sump pump and/or a permanent dehumidifier in the crawl space after sealing up vents. Ask mold abatement firm for assessment of crawl space to determine the best options for removing mold.
- Toilet's wax seal has failed. Flooring and joists immediately around toilet are damp and black with mold. Moisture meter confirms that floor damage extends about 18" to 24" around toilet. This plumbing leak might not be related to the mold on the ceiling, but it's best to repair the problem before the floor becomes unstable.
Recommendation. Replace wax ring on toilet along with damaged flooring.
- No vinyl wallpaper and no traces of roof, window, door, or plumbing failures (other than the aforementioned wax seal).
- Relative humidity and dew points in cottage are abnormally high (RH well above 60%), and temperature is about 68?F. Readings near plank ceiling (adjacent to mold) are even higher. Interior space feels damp and clammy.
Recommendation. Hire a mechanical engineer to run load calculations on cottage to confirm heat pump size and placement of supply/return diffusers. The current unit is probably too large for the cottage, and if it is "short cycling" (running for very short periods of time), that would help explain the excess humidity, high dew points, and inadequate circulation inside building. Replace HVAC system if engineer determines it is oversized.
Also, install a programmable thermostat limiting operator control from 70 degrees F to 78 degrees F in cooling mode and 65 degrees F to 75 degrees F in heating mode. Educate owner about keeping space properly conditioned all year, even when not in use.
- Many abnormal and inconsistent gaps exist between wood ceiling planks. It's possible to detect drafts moving through ceiling planks, despite faced blanket insulation.
Recommendation. Ask a qualified carpenter if ceiling planks can be properly adjusted/sealed, or find out if the entire ceiling must be replaced.
- Black mold spores are widespread on damp ceiling planks. It's unclear how deep the mold has penetrated the ceiling material.
Recommendation. Ask a mold abatement firm for assessment of ceiling to determine best options for removing mold.
Additional general recommendations. Place portable dehumidifier in cottage to dry out interior while repairs are in progress. Then monitor temperature/humidity for at least one year (visually inspect attic and crawl space quarterly) to confirm problems are all resolved. Finally, hire a competent facility manager (and a different general contractor) to manage construction and operation of additional facilities! Finally, thanks to all the TFM readers who offered such great feedback.
Crane is a mechanical engineer and regional property manager with Childress Klein Properties, a leading real estate developer and property management services provider in the Southeast.
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