Causes of Mold in the Home
Humidity Causes Mold
If you live in an area of high humidity such as on the coast or near a large body of water then this can cause mold growth in your home. Mold only needs humidity levels to be higher than 55% to grow. Using your home's HVAC system's climate control can also make the humidity vary inside greatly compared with outside as it artificially heats or cools your house. The humidity can also vary between different rooms in your house so using several humidity sensors to monitor humidity in each room can be helpful. Dehumidifiers can then be used to bring the humidity to a level where mold cannot grow.
Some people also use humidifiers in their homes. If you need to use a humidifier in your home you should make sure to keep the humidity below 55% to avoid mold growth.
Mold Caused by Leaking Pipes
Water leaks from pipes are a common cause of mold growth. Often the leak can be in a place out of view and can go undetected for a long period of time. By the time the leak has been discovered mold will probably have already begun to grow, especially if the leak is in a place hard to find such as within a wall cavity, behind panels, etc.
Flooding Causes Mold
It is almost inevitable that some mold problems will develop after your home has been affected by flooding. Obviouly 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 there is a huge risk of mold growth. Some dangerous molds require more extreme conditions to grow, such as the toxic black mold Stachybotrys chartarum which requires material to be very wet for at least a few days to grow. A flood satisfies these conditions putting your home more at risk of being infected with dangerous toxic molds.
A Leaking Roof Causes Mold
As with leaking pipes, a leaking roof may not be discovered until it has already caused mold to grow. You should check the attic for any water intrusions caused by the roof leaking and also look for water damage or mold growing on your ceiling under the roof or attic.
A Damp Basement Causes Mold
Basements and crawl spaces often have higher moisture or humidity because they are usually not well ventilated. They are also often colder and more condensation occurs in colder temperatures which leads to dampness and humidity. Also any water from leaks in your home will often end up running down to the basement because it is below all the other rooms in the house. Not only is mold likely to grow in these rooms but because they are usually neglected mold growth may not be discovered until it is well set in.