Each Fall and winter, RESTORx is called to investigate the black streaks that form on ceilings and walls of homes. These calls are usually a panicked call to see if their house is “infested” with mold. These streaks normally outline the framing members of the house behind the drywall and are the sign of one of two problems; mold problems or smoke problems. Both problems occur during the heating season.

If it is a mold problem, the streaks appear on the framing members as this area is typically a little colder than the surrounding cavities that are insulated. Moisture can condense on cold surfaces and since mold is always caused by moisture, this can be the first place for mold to grow. We typically find it worse on the inside corners since air currents that evaporate moisture don’t penetrate the inside corners as easily. The first photo below shows an example of this problem.

Example of inside corners
Example of mold


However, most of the time when we see these streaks it’s due to smoke/soot. Smoke is also attracted to cold surfaces so it can appear in the same places as mold caused by condensation. The best way to identify if it’s smoke is to look for round black spots in the areas of streaking. Smoke is magnetic and is attracted to the drywall screws that hold the drywall to the framing. If you find these spots, you can be assured it is most likely a soot problem. These are commonly caused by candle burning or a malfunction of the furnace or fireplace. Restoration usually consists of washing and painting the surfaces and is often covered under homeowner’s insurance. Look closely at the second photo and you will see the black spots over the drywall screws.

Example of smoke.

*All the above information is trademarked and Property of RESTORx. We feel it is the most current & accurate information available, but we do not guarantee it be the only proper solution.  Written by Stephen Gitz, CR, WLS, CMP