Contact a Service Provider Now

Find

Near

Type a few letters of City name

Retrieving local listings...

Need help choosing a provider?

Call us at (800) 351-9563

Not sure what service you need?

(800) 351-9563

Live chat with a mold expert

Mold in attics due to ducting issues

Click on one of the images below to learn more about that item.

Jump to Slideshow

What types of mold problems are found in attics with faulty ducting?

Mold due to attic ducting failure

Disconnected, broken and improperly installed ducts are a major cause of sheathing degradation and mold growth. The reason is straightforward; if an exhaust duct, such as a bathroom vent, is disconnected, all the warm, humid air from the house is pumped directly into the attic.  This moisture condenses on the cool roof sheathing and eventually causes mold growth and sheathing failure. 

  • Systemic mold and moisture.  If the problem is severe and the attic has a compounding problem, such as poor ventilation, the moisture buildup can occur throughout the entire attic assembly.  This often occurs in houses with poor passive ventilation in the roof.  
  • Focused mold and moisture.  In many cases, the faulty ducting effects only the area immediately surrounding the disconnected duct.  Both moisture and mold growth will be limited to 5-10 sqft. area above the defective ducting.
Mold growth on sheathing due to ducting.

What other types of attic duct problems can occur?

  • Faulty supply ducts.  If a supply duct is broken or disconnected, warm, moist air from the furnace can escape directly into the attic.  
  • Faulty cold air return.  This is a much more common scenario, as most homes with forced air systems locate the supply ducts in the crawl space and return ducts in the attic.  If a return duct is damaged, air from the attic can be pulled directly into the HVAC system.  This air can bring along many undesirable particulates, such as mold spores, fiberglass insulation, rodent odors, etc. 

How do mold remediation contractors deal with attic ducting problems?

  1. Address the initial duct problem.  This may include simply reattaching a disconnected exhaust line or replacing an entire cold air return.  Typically however, the ducting repair is straightforward and inexpensive.
  2. Apply fungicide to areas with mold contamination.
  3. Dryout damp framing and sheathing.
  4. Apply encapsulant.

Photos

At the risk of stating the obvious, these photos represent how not to install attic ducting.  The first image highlights several problems.  First, they used dryer ducting.  Not only is this far less durable than standard exhaust fan ducting, it is uninsulated.  Second, the ducting exits the fan vertically then turns back down and exits the house through a soffit vent.  Not good.  Third, the ducting is attached with duct tape.  Bathroom exhaust fan ducting should be installed with heavy duty zip ties, foil tape and sheet metal screws.

bath fan ducting problems

Recent Inspection Report Involving Improper Ducting and Ventilation

Work #: 102074

General Information

  • The home owner has been experiencing respiratory issues and his doctor recommended an indoor air quality inspection of the home.

Furnace / HVAC

  • Electric forced air.
  • Recently cleaned.
  • Recently serviced.
  • Filter installed and clean.
  • Ducting very leaky, and in need of normal mobile home duct sealing.
  • Few rodent droppings noted in HVAC ducting.

Recommendations

  • Perform duct sealing to limit the loss of heated air and the infiltration of crawlspace air into the living space.

Living Room:

  • No increased moisture content noted in tested building materials.
  • No significant visible mold growth observed.
  • No suspicious temperature differentials noted on inspection with FLIR.
  • No obvious signs of water damage.
  • Minor water staining noted on window sills, likely secondary to periods of condensation.
  • Older, non-functional pellet stove located in this area.
  • RH: 37.3%     Temp: 68.4F     CO2 = 656ppm     CO = 0ppm

Recommendations

  • Do not use pellet stove unless serviced and certified by a licensed professional.

Kitchen:

  • Kitchen range exhaust hood functional and ducted to the exterior.
  • Small gap at ceiling around range exhaust hood ducting.
  • Absolutely no signs of past or present plumbing leaks.
  • No increased moisture content noted in tested building materials.
  • No significant visible mold growth observed.
  • No suspicious temperature differentials noted on inspection with FLIR.
  • No obvious signs of water damage.
  • RH: 38.3%     Temp: 67.9F     CO2 = 703ppm     CO = 0ppm

Recommendations

  • Air sealing may be performed around kitchen hood exhaust ducting to limit the loss of heated air and the infiltration of attic air into the home.

Laundry Room:

  • Furnace closet located in this area.
  • No exhaust fan currently installed.
  • No obvious plumbing leaks.
  • Large open chase in wall paneling behind washing machine.
  • Dryer exhaust ducting securely connected and vented to the exterior.
  • No increased moisture content noted in tested building materials.
  • No significant visible mold growth observed.
  • No suspicious temperature differentials noted on inspection with FLIR.
  • No obvious signs of water damage.
  • RH: 38.1%     Temp: 67.7F     CO2 = 681ppm     CO = 0ppm 

Hall Bathroom:

  • No exhaust fan currently installed.
  • No obvious signs of plumbing leak.
  • Small stained area on ceiling above tub, likely secondary to a historic roof leak that has been resolved.
  • No increased moisture content noted in tested building materials.
  • No significant visible mold growth observed.
  • No suspicious temperature differentials noted on inspection with FLIR.
  • RH: 37.8%     Temp: 67.8F     CO2 = 664ppm     CO = 0ppm

Recommendations

  • The exhaust ventilation in this area is inadequate, it is recommended that a Panasonic Whisper Green 80CFM exhaust fan be installed and set to run at 30CFM continuous flow, and for 60 minutes at 80CFM once motion-sensor has been activated.

Office:

  • No increased moisture content noted in tested building materials.
  • No significant visible mold growth observed.
  • No suspicious temperature differentials noted on inspection with FLIR.
  • No obvious signs of water damage.
  • RH: 38.2%     Temp: 67.2F     CO2 = 682ppm     CO = 0ppm

Master Bedroom:

  • No increased moisture content noted in tested building materials.
  • No significant visible mold growth observed.
  • No suspicious temperature differentials noted on inspection with FLIR.
  • No obvious signs of water damage.
  • RH: 39.3%     Temp: 66.7F     CO2 = 674ppm     CO = 0ppm 

Master Bathroom:

  • No exhaust fan installed in this area.
  • Increased moisture content noted in vinyl flooring behind toilet, suggesting a failure of the wax ring.
  • O/wise OK
  • Temp: 40.1%     RH: 66.4F     CO2 = 704ppm     CO = 0ppm

Recommendations

  • The exhaust ventilation in this area is inadequate, it is recommended that a Panasonic Whisper Green 80CFM exhaust fan be installed and set to run at 30CFM continuous flow, and for 60 minutes at 80CFM once motion-sensor has been activated.
  • Establish containment.
  • Install HEPA scrubber for negative pressurization throughout the duration of work.
  • Disconnect toilet.
  • Remove affected vinyl flooring around leaking toilet.
  • Remove damage subflooring and replace with appropriate materials.
  • Perform detailed HEPA vacuuming of the entire contained area.
  • Apply EPA-registered anti-microbial agents to the entire contained area via ultra-low volume fogger.

HWT Closet:

  • No increased moisture content noted in tested building materials.
  • No significant visible mold growth observed.
  • No suspicious temperature differentials noted on inspection with FLIR.
  • No obvious signs of water damage.
  • Temp: 40.1%     RH: 66.4F     CO2 = 704ppm     CO = 0ppm

Crawl:

  • Recently renovated.
  • Vapor barrier appears intact.
  • No obvious signs of leaking or standing water.
  • Preliminary evaluation appears normal, with an intact belly-wrap.

Find a Environix Certified Attic Mold Remediation Contractor: [show/hide]