outline of studs through wall??

Has anybody seen this before? You can see where the studs and blocking are through the drywall. The first picture is on an exterior wall. The second is not an exterior wall but is a vaulted scissor truss with attic space above. They almost look like shadows and are only on the top half of the wall.

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Sounds like ghosting.

I see it all the time, hard to explain to clients its not a leak…

I agree with Joe and James

Ditto…ghosting. Here’s a few more resources on it:



I have these in a home with a wood burning fireplace. See them often here in the mountains due to fireplaces.

Great PDF Kenny, thanks

Caused by:

  1. Excessive humidity in the house.
  2. Lack of proper wall and attic insulation.
  3. Surface of wall, in the winter, goes below the dew point, gets wet (from condensation) and attracts the dust, soot and cat hair in the room.
  4. Can promote surface mold growth.

Hope this helps;

Ditto to all. Also I’ve run across that with no fireplace but the folks liked burning candles. In fact, the candles seemed to cause more widespread soot than either fireplace or woodstove.


While these may be contributing factors, they are not the only causes, or even the best explanation. Absent of proof of any of this, it is pure conjecture.

Older homes had virtually no insulation in walls. many have failed insulation in attics (compression). I rarely see ghosting in 1950’s homes, with a total lack of insulation.

I have also tape sampled stains, only to have them come back negative for mold.

Prove the wall dips below the dew point.

Nice possibilities, but not necessarily correct.

I have seen this. many times.

Winter, outside temp around 22 F. Pakistani family in a 1950’s ranch. Relative Humidity, inside, was 65 %. House with no insulation. Wooden framed with brick veneer. Shadowing on the walls. Also took a tape sample from the wall and ity came back as Pen / Asp.

Thermal imaging revealed the stud surface of the wall, where the studs met the drywall, was 7 degrees below the dew point. There was even a small area, on the windward side of the house, where there was a thin sheet of ice on the stud area.

I told them to keep the humidity down to about 25 - 30%. Also that it would help if the insulated the walls.

Also, in this house (not a pre-purchase inspection, but a consult regarding this problem) there were unsealed can lights and liquid water condensing on the roof rafters over the lights.

Would you consider this proof, Joe?

The unique and specific case with causal factors mentioned above is not typical of the forces in action in the vast majority of ghosting! Will’s fairly quick and recent rise as the building science specialist here was just that…too quick and recent to fully appreciate the many forces at play in some building science phenomena. I have been a part time participant/teacher/researcher in building science since 1977 and still am amazed by some of the findings of gurus such as Drs. Joe Lstiburek, Bill Rose, John Straube, Anton ten Holde and others.

In the more general cases of ghosting, high humidity and dew point are not usually involved. See: http://www.homeenergy.org/archive/hem.dis.anl.gov/eehem/98/980109.html


I bow to Brian, and please understand that I am only speaking from my inspection experience, and my understanding of Building Science (which I am still studying) but am helped from my physics background (Physics being the basis for all physical science :mrgreen:)

As I have stated here before, it is ALL about the specific climatic conditions in your specific area.

The CHicagoland area has 3 humid seasons, Lake Michigan (the GIG heat sink) and the reverse low pressure systems that fly through this area (look up, Lake Effect Snow).

But there is also the history of consruction in this area.

  • The Chicago Fire. Move to ll masonry construction.
  • The Building Dept. Run by the Unions, for their benefit. Also, take into account their expertise (really great. Most Chicago unions arfe really guilds, educating and bringing up their members) but there is also the simultanious rise in the Union’s political clout.
  • Great Architects. Frank Wright, Louis Sullivan, Goerge Maher. The beginnings of pocket windows, cement shingles, Stucco, balloon framing, and now the notorious split faced block.

Differnt areas have different conditions and a good inspector will educate themselves to those conditions.

The houses that I mentioned were all built (ranches, no insulation, in a middle class north Chicago suburb) were built during the build-up of the Navy Orion anti-sub project. These tyype of houses were built for senior enlisted serving at the Glenview Naval Air Station, which was the headquarters of the Orion project.

So, I looked up the orginal development and came to understand their particular designs, and flaws, given how conditions are now.

All of these contribute to the “building science” aspect of our work.

Be well informed, keep educating yourself, because things ALWAYS change, Study, read, look up (Google makes that MUCH easier, now) and grow. In the finest NACHI tradition, be the BEST that you can be. Set yourself apart from the others.

And make more money because of what you have invested in yourself.

Here’s the part I find most fascinating:

Why in the world would anyone be measuring relative humidity in a residence? With a 65% RH, I would imagine there would be mold.

But, since when is RH part of any SOP?

This was not a pre-purchase inspection, but a consulation.

If RH readings help to discover the cause of a problem, then why shouldn’t they be done. Meter doesn’t cost alot and it helps.

I get about 52% of my revenue from consultations. In this bad market, you kinda have to diversify, correct?

Hope this helps;

http://www.buildingscience.com/documents/digests/bsd-150-black-stains-on-carpets-and-ghosting-of-framing/?searchterm=black stains on walls

Say that and do not disgaree with it. I was just discussing findings that I have experienced in my area.

Good to learn.

I’ve seen this many times in homes in Northern New England. Mostly with oil fired boilers & furnaces. Occasionally, these devices can have blow-backs or puff-backs which send particles back into the home. Many times people do not even realize that they have happened and are puzzled by the collection of soot particles on the studs, fastener heads or any plastic switch plates or receptacle plates. Any time I see this, I recommend further evaluation of the heating system by a heating professional. Often times the accumulation will be worse on the upper levels than the lower levels. If you ever come across this again, go to the utility room and run your fingers across the studs above the heating unit. You’ll be surprised by the blackness on your fingers. I’ve attached a couple of pictures as an example of my most recent ghosting. The one with the dark ceiling is actually the furnace room and that is soot the other two pictures are walls of the second floor. The furnace had recently been replaced and it became obvious as to why.