What Are Those Mysterious Black Marks in Your House?

So was something supernatural going on or is it something a bit more simple?  The photos were taken in a home that I recently visited.  The homeowner had called me quite upset about extensive black marks which had recently formed on the walls of the master bedroom.  No where else in the home, only the master.  The owner reported that there was actually a black residue settling on all the horizontal surfaces also and was understandably quite concerned about what might be causing this issue.  As I really enjoy these types of challenges I was looking forward to the visit.

After I arrived,I took a quick walk through the home and confirmed that the black marks seen in the pictures were only in the master bedroom.  For a little background, the home was built in the '70's and this room has a vaulted ceiling…1 story resting on the exterior wall and the interior wall basically 2 stories high.  I went into the attic in order to see the backside of those walls.  The floor of the attic had additional insulation installed,and the vertical walls shared with the bedroom were insulated, but the insulation was brittle and starting to fall away from the wall.

Discussion with the folks living there indicated a few key points:

• The door to the master bedroom was generally closed at night (it also had some additional sealing around it)
• Since this occured in our winter season, no heating or air conditioning was being used
• Candles were frequently burned inside the room

It didn’t take long to come to a conclusion here…

1. With the door closed and no circulation,the temperature in the room and the humidity would slowly rise during the night
2. The candles burning produce not only additional moisture (a byproduct of combustion is water) but also varying degrees of soot
3. As the outside temperature cooled down, including inside the attic, a dew point was reached on the walls particularly where the insulation is failing.  Thermal imaging confirmed 
4. The smoke and dust particles are attracted to the small amount of condensation on the walls resulting in the black marks!

If there is poor air circulation, burning a single candle a week can cause a significant amount of darkening on the walls and residue settling on surfaces.  Believe it or not, damage can be quite extensive.  Candle soot can be difficult or impossible to clean out of furnishings, and heating and air conditioning systems can be permanently damaged.  None of this takes into account the potential health implications.

Bottom line: Don’t burn candles  in your home without ensuring that there is adequate ventilation!  If you must burn candles here are a few tips:

• Pay attention to the quality of the candles
• Keep the candles out of a draft
• Keep wicks short to reduce sooting
• As with everything, use in moderation!

Although the “dark shadows” in this case were not caused by anything supernatural, they can be an indication of significant problems in the home which could lead to extensive repairs or even health problems!  

If you have issues you can't track down, contact us at 4D Building Solutions.

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