Powder Valley Inspections Blog

Recently I have encountered effects from airborne soot/dirt/particulates  in a home which, when deposited,  is referred   to as “ghosting” by the industry.    This can be described as  particulate deposits on window blinds, ceiling fans, inside of kitchen cabinets and on appliance surfaces.  But most striking is this deposition on gypsum board surfaces of exterior walls where  stud members lie beneath as viewed below.

The problems are related to four deposition mechanisms: filtration, electrostatic attraction, thermal deposition due to Brownian motion and impaction.

All of these mechanisms require really tiny particles – particles that can become aerosolized or lofted into the air and remain airborne for many minutes or hours. Big particles are not related to the problems observed. Big particles fall out of the air too fast – their movement and distribution is dominated by gravity rather than airflow, electrostatics or molecular movement such as Brownian motion, http://www.buildingscience.com/documents/digests/bsd-150-black-stains-on-carpets-and-ghosting-of-framing?full_view=1 .

The sources are varied but include soot from candles, fireplaces, incense, tobacco smokers, pilot lights, gas water heaters and furnaces, etc as well as fine dust from concrete and gypsum board finishing and just plain dust.   But according to the article referenced above the largest source of particulate is from carpet filtration i.e.  when air flows through a carpet the carpet acts like a filter and removes particles from the air that passes through it.  Air moves under baseboards in exterior and interior walls due to air pressure differences caused by wind, temperature differences and the operation of heating and air conditioning systems. As the air moves under baseboards, the carpet at these air pathway locations becomes discolored if the air contains particulates.

The solution?  Darker carpets, regular furnace filter maintenance and no or fewer candles being used in the home.

Has it made it to the West coast?  The “Chinese Drywall” phenomena where, mostly between 2004-2008, but possibly as far back as 2001,  boatloads (approx. 250,000 tons), http://chinesedrywall.biz/,  of drywall made from suspect materials was used in the construction of the sheet rock.  Conventional drywall, being made from gypsum has benign properties in comparison in that severe corrosion will result to some metallic components,  but always copper, in the home from the imported stuff.  This is due to the release of a medley of sulfur compounds from the gypsum or possibly a spray on coating that is applied prior to shipping.  Obviously the other hint that you have it in a home is the smell and, of course, you can check for manufacturer markings on the sheet rock.  Also there is in addition to an unfamiliar texture and  gray color the possibility of chronic health problems.  So the initial determination would include: checking the wiring at the outlets and main box or the copper coils in refrigerators and/or air conditioners for corrosion (including frequent or short replacement of these components),  smell of sulfur in the home,  manufacturer markings (possibly up to 36) with “Made in China” stamps and “Knauf Tianjin” markings instead of  “Gridmarx” markings. (http://www.chinesedrywall.com/index.html).  Though bear in mind that none of these signs are definitive for the presence of the drywall in question.  Only physical (bulk not air) testing by a qualified lab will determine it’s presence with certainty.

Having said that, have I heard of or seen any problem drywall in Oregon?  No.  I have heard (unsubstantiated) that it has been found in WA state, however.  Florida is ground zero.