The only way to know whether you have black mold in your house is to have the mold tested by a qualified mold laboratory. If you have visible mold growth, you can easily take samples for laboratory testing by using clear scotch tape. All you need to do is to cut 2-3 inches of clear scotch tape and stick it onto the surface with mold growth. Then remove the tape and stick it onto a plastic bag and then send it to a lab. For details on mold testing click Mold Testing Kits For Homeowners And Property Managers.
If the mold is not visible but there is musty smell, you can take air samples. While negative air samples do not necessarily mean there is no mold growth, air samples can help in detecting hidden mold growth. For details on how to take air samples, please call 905-290-9101.