The key to maintaining healthy indoor air quality in your home is by controlling temperature and humidity levels. For mold to colonize, the fungal spores need three ingredients: oxygen, food source and moisture.
The steps below illustrate the most common places to look for contamination in your home, based on a sub-tropical climate with a high humidity level.
1. Check your return filter
If there are roaches, lizards or geckos in your return filter it’s a sign that the return air cavity is open to crawl space. If insects can get in, so can contaminants.
2. Check your garden
If you have a garden next to brick, the soil level should not be higher than where the slab meets the brick. When you water the garden, the moisture absorbs into the wall and is sucked into the interior cavity, increasing the humidity in the cavity and causing mold growth. It is also a haven for termites in these conditions.
3. Check your attic
Inspect the color of the insulation around the equipment in your attic. If the color is darker near the unit or air ducts, this is a sign that the insulation is acting as a filter. This decreases the efficiency of the unit because of the amount of heat entering from the attic and reduces indoor air quality due to the amount of dust coming in.
4. Check your thermostat
Never set the fan in the “on” position while the system is in cooling mode. Once your thermostat reaches temperature, it turns the compressor off. If the fan is in the “on” position, it will cause warm air to go across the warm, wet coil which increases humidity and can cause mold to grow in the duct work.
5. Check your supply grills
Remove a few of the grills that are closest to the inside central unit and look at the insulation behind the grill for discoloration. If the box has internal insulation, the color should be completely black. If there is green discoloration and the insulation is murky to the touch, mold is likely present
6. Check all water sources
The most common places household mold is found are under sinks, cabinets and vanities, washing machines, dishwashers and window sills. It can take weeks for it to be noticed. If the inside of the cabinets are never inspected and you see the evidence of water on the floor under the cabinets, you may already have a serious black mold problem.
7. Check your filter
Make sure the filter is clean and replaced every 30 days. If it is a three month filter, replace every 45 days.
8. Check your supply air ducts for leakage
The supply ductwork on most homes that are 10 years old or older can become unsealed. Leaky ducts make your home run under negative pressure and can increase the dirt and humid air filtration into your conditioned space. This can also increase the heat load on your A/C system and cause your home to be dusty.
9. Check all of your exterior walls
If you have vinyl wallpaper on an exterior wall, it is very important to check for water intrusion. When humidity levels are high, the moisture comes through the walls to your conditioned space where it’s drier.
In addition, the glue on the wallpaper can act as a fungi food source. Under these conditions, the perfect environment for mold has arisen amongst the three ingredients for the mold growth: oxygen, food source and moisture.
10. Check your dryer vents
You should make sure your dryer vent is properly exhausted through either the side wall or the roof line. If the exhaust becomes dislodged and is exhausting moisture into the attic, it would encourage mold growth. This is usually noticeable by the amount of lint found in the attic.
If you meet any of the criteria above, you should seek the advice of a certified indoor environmentalist or indoor air quality specialist to resolve these issues correctly.
About this Angie's List Expert: Pablo Maique is the owner of IAQ Services, providing air duct cleaning in Metairle, La. IAQ Services specializes in home air quality, mold remediation, HEPA filtration systems, dehumidifiers and dryer vent cleaning and is a recipient of the 2012 Angie’s List Super Service Award.
As of July 8, 2013, this service provider was highly rated on Angie's List. Ratings are subject to change based on consumer feedback, so check Angie's List for the most up-to-date reviews. The views expressed by this author do not necessarily reflect those of Angie's List.