Causes of Mold in Homes

Mold needs these conditions to grow in a building:

  • Mold spores
  • A food source (carpet, drywall or wallpaper for example)
  • Oxygen (air)
  • Darkness (mold will not grow in ultraviolet light)
  • Moisture (flood, water leaks or humidity)

As you can see all conditions on the list are always going to be present in homes. According to the Environmental Protection Agency moisture  causes mold. Molds reproduce by means of tiny spores; the spores are invisible to the naked eye and float through outdoor and indoor air.  Mold may begin growing indoors when mold spores land on surfaces that are wet within 24 to 48 hours.

The Main Causes of Mold in Homes

  • water leaks are common causes of mold in homesWater leaks from plumbing, windows, roof or gutters
  • dampness coming through walls
  • Poor ventilation
  • Inadequate heating
  • Failing to dry water quickly enough after leaks or floods
  • A wet or overly damp crawl space
  • A wet  or overly damp basement
  • Condensation from high relative air humidity
  • Too much steam or water vapor from showering, cooking, washing and clothes drying

Secondary Causes of Mold in Homes

If the weather’s been very humid or if it rains for several days it’s common to see mold start to grow on household surfaces. If you live near a lake or ocean where humidity in the air is naturally high, then mold growth can be on ongoing challenge in your home. You may wish to us a dehumidifier in your home. Try to keep the humidity below 55%.

Leaking pipes causes mold in homes
Water leaks from pipes are a common cause of mold growth. The worst leaks are the ones that go undetected because they are hidden out of view, like inside a wall. By the time you discover these leaks mold has usually started to grow already.

Leaks in roof
A roof that leaks into the attic might not be discovered until it’s already lead to mold growth.Check the attic regularly for leaks and keep an eye on the ceiling below the attic. If you notice any signs of water damage on the ceiling then you probably have a leaking roof.

Condensation collects on cold metal pipes as well as on cold concrete floors, even if there is carpet over the top, and on walls. Places like these where condensation occurs are prime spots for mold growth.

Poor ventilation causes mold in homes
If your home is poorly ventilated it can create pockets of stagnant moist air which mold thrives in. Poor ventilation also means wet surfaces dry out more slowly. Ventilation is especially important in rooms such as the bathroom and the kitchen where there is a lot of steam.

Wet Clothes
Damp clothes left in a pile waiting to be washed for more than a day can lead to mold growth. Clothes left wet for over a day after being washed may also end up fostering mold.

Drying your clothes in a dryer releases a large amount of moisture into your home if the drier is not vented outside the house. Clothes drying inside on indoor clothes racks will also create a build up of moisture inside unless the room is well ventilated.

Flooding causes mold in homes
It is almost inevitable that some mold problems will develop after your home has been affected by flooding. Obviously your house will be very wet for a long time during a flood, taking days or even weeks to dry out. Since mold only needs a suitable surface to be wet for 24 hours before it can grow this means there is a huge risk of mold growth. Speedy water damage repair is essential.