(Bob Ruby, Home Inspection Solutions Missoula Montana, 406-646-6182)

House fires caused by dryers are much more common than generally believed.
Fires caused by dryers in 2005 were responsible for approximately 13,775 house fires, 418 injuries, 15 deaths, and $196 million in property damage. Most of these incidents occur in residences and are the result of improper lint cleanup and maintenance. (National Fire Protection Agency)

Fortunately, these fires are very easy to prevent.

How your dryer works: 
Clothes dryers evaporate the water from wet clothing by blowing hot air past them while they tumble inside a spinning drum. Heat is provided by an electrical heating element or gas burner. Some heavy garment loads can contain more than a gallon of water that will become airborne water vapor and leave the dryer and home through an exhaust duct, more commonly known as the dryer vent.

A vent that exhausts damp air to the home's exterior has a number of requirements:
•       It should be securely connected to the vent tube. The connection is usually behind the dryer but may it be under it. Look carefully to make sure it’s actually connected.
•       It should not be restricted. Dryer vents are often made from flexible plastic or metal duct tube, which may be easily kinked or crushed where they exit the dryer and enter the wall or floor. This is often a problem since dryers tend to be tucked away into small areas with little room to work.
Vent tubes should also be as straight as possible and cannot be longer than 25 feet. If there are any 90-degree turns in the vent reduce the allowable 25-foot requirement by 5 feet, since these turns restrict airflow. Air flow restrictions are a potential fire hazard.
However, special vent hardware is available that is designed to turn 90 degrees in a limited space without restricting the flow of exhaust air. 
•       One of the reasons that restrictions pose a fire hazard is that, along with water vapor evaporated out of wet clothes, the exhaust stream carries lint – highly flammable particles of clothing made of cotton, wool and polyester.
Lint can accumulate in an exhaust duct, reducing the dryer’s ability to expel heated water vapor, which then accumulates as heat energy within the machine itself. As the dryer overheats, a subsequent mechanical failure can trigger a spark, which can cause the lint trapped in the dryer vent to burst into flames. This condition can cause the whole house to catch fire.  Fires generally originate within the dryer but spread by escaping through the ventilation duct, incinerating trapped lint, and following its path into the home’s walls.

Moisture Problems & Defective Installations

• Your dryer exhaust vent should terminate at the exterior of your home. A dryer vent that terminates in the crawlspace or attic, it can deposit moisture there, which can encourage the growth of mold, wood decay, and other structural problems.  This is a defective installation & should be corrected.
  
• A vent that terminates just under the attic ventilators is also a defective installation & should be corrected..
• Make sure that your dryer vent terminates at the exterior and away from any doors and windows so that damp, exhausted air won’t re-enter the home. If not this should be corrected.
• The end of your dryer vent should have a free-moving damper closeable gravity or automatic damper (a backdraft damper) installed to keep out birds and other pests that like to build nests in this warm environment.  In the past screens were used for this purpose, screens are now considered a defective installation because a screen can block lint and other debris, causing it to accumulate and leading to a house fire.  If it’s safety accessible, make sure your dryer vent is unobstructed and that the damper works properly.

What Is Mold?  (Bob Ruby, Home Inspection Solutions Missoula Montana, 406-646-6182)
Mold is classified as a fungus and is part of the natural environment.  Outdoors, molds are essential for breaking down dead organic matter, such as fallen leaves and dead trees.  But indoors, mold growth should be prevented.  Not only is it unpleasant, as evidenced by its musty odor and unsightly staining, but it can cause significant and irreparable damage to a home’s structural components, as well as furnishings and carpeting. 

How does it grow?
Molds reproduce by means of tiny spores, which are invisible to the naked eye and float through the air.  Mold may begin growing indoors when its spores land on surfaces that are wet.  There are many types of mold, but none of them will grow without water or moisture, which is why mold prevention begins by maintaining clean and dry surfaces wherever possible.

Health Effects of Mold
Molds have the potential to cause health problems by producing irritants, allergens (which are substances that can cause allergic reactions), and even potentially toxic substances called mycotoxins.  Inhaling or touching mold or mold spores may cause allergic reactions in sensitive individuals and even in those not generally allergic.  These reactions can include hay fever-type symptoms, such as sneezing, a runny nose, watery eyes, and skin rash (dermatitis).  Allergic reactions to mold are common, and they can be immediate or delayed.  Molds can also cause asthma attacks in people with asthma who are allergic to mold.  Very serious respiratory ailments can result from prolonged exposure to mold.
 

How do I get rid of mold?  
The key to mold control is moisture control.  If mold is a problem in your home, you should clean up the mold promptly and fix the moisture problem, because mold cannot grow unless it has a water source, which usually means a plumbing leak or some structural damage that’s allowing water intrusion from the outside.
 If you discover a leak or have experienced flooding, it’s important to completely and thoroughly clean and dry any water-damaged areas and items within 24 to 48 hours to prevent the onset of mold growth.  Vinegar is effective on porous surfaces, and bleach is best on non-porous surfaces.  Some severely water-damaged items that cannot be fully dried out or cleaned may need to be disposed of, such as books and rugs. 

Be aware that it’s impossible to get rid of all mold and mold spores indoors.  Some mold spores may be found floating through the air and in household dust.  This is normal.  But mold spores will not grow into mold if moisture is not present.   If you clean up the mold but don't fix the water problem, then, most likely, the mold problem will recur.  If mold damage is extensive, professional intervention may be required.  The easiest way to prevent mold growth indoors is by keeping your home clean and dry and monitoring indoor humidity levels.