“ghosting” of studs showing on walls
davebl
| Posted in Energy, Heating & Insulation on
Thought I’d post a newbie question to see what everyone thought. When I bought my house 11 years ago, Many of the exterior walls had darker areas showing through on the interior, showing where the studs are. I painted them but now they’re starting to show through again. What’s up with that?
Replies
your studs are usually the coldest part of your wall system..
so they spend more time below the dew point and you get a little more condensation on them that on the adjacent insulated wall area
the minute dust particles will stick to the slightly more moist areas and eventually you will see this "ghosting"
this is especially true if you have combustion products in the air as the soot particles are attracted to the stud temperature differential
a special culprit is burning candles
Dust/smoke. More likely if someone smokes in the house, you burn a fireplace or wood stove, or burn a lot of candles. Or can be due to very fine dust (not simple "dirt" dust).
Theories as to why the smokes collects this way involve condensation, convection, and/or static charges. Clearly it's in part due to the colder temps at the studs, but the precise mechanism has not been well researched.
You mean you have not read this yet?Carbon-based Linear Particle Accretion in Aqueous Matrix as a Function of the Kinetic Molecular Deficit in Proximity to Thermal Bridging of Dendro-derivitive Structures.
I'm interested but I think I'll wait for the DVD.
I read the title. Did you get any farther than that?
If your view never changes you're following the wrong leader
Nope.I once had the job of cataloging, and filing copies of all scientific articles of interest to the Forest Pathologist and Forest Entomologist at Colorado State. The titles of some of the articles were hilarious. I read quite a few, just to see what the fuss was about (I also had to read a bunch of them to generate "key word" lists for the database).The catalogue was computerized for academic searches, but the articles were all in hardcopy files...you could say I was involved with a pre-internet version of Google in the 80's. Of course, that is how I got to be friends with Al Gore. ;o)Your mention of the lack of a definative mechanism for stud ghosting, took me back to my days of wading through scientific articles. Funny.
I really would like to like the convection/increased impaction theory because of its elegance. (Especially now that I've learned the formal name: "Carbon-based Linear Particle Accretion ..." LOL)But I've come to believe the condensation theory: I've seen many examples where an entire square area had the shadowing, with a 17 1/4" width (16" oc plus an additional 3/4" on each stud/rafter, and in several of those cases I've been able to verify the lack of insulation in that spot.I don't believe the convection theory would fit that situation.May your whole life become a response to the truth that you've always been loved, you are loved and you always will be loved" Rob Bell, Nooma, "Bullhorn" "We Live" http://www.youtube.com/watch?v=7kuBgh0VCqI&mode=related&searchAnd Annie Ross's "Twisted" http://www.youtube.com/watch?v=8lqivrCIRGo&mode=related&search=
Edited 9/26/2007 10:39 pm ET by rjw
Don't overlook the surface texture of the drywall over the studs. Most drywall finishers make one long vertical stroke when filling screw or nail holes. This fills the drywall paper with coumpound over the stud making it smoother and less absorbent than the area between the studs. I have seen this a lot. Special primers are made to help correct this problem. One new installiations I insist on skim coating the whole wall. Good Luck Jay
Jay, have you found that skim coating gives you the result you're looking for? We've done just that on the last couple of jobs and our painter says he can do a better job just using a high-clay content primer.
To the OP, it's condensation attracting interior pollution. At my family's camp, which has a woodstove and a sheetrocked cathedral ceiling, you could clearly see the outline of the fiberglass batts in the rafter bays (not the best insulation job!). I painted over it, but the real fix is to insulate better and break the thermal bridging.
Mike: I got burn't not skim coating. Shows up on higher gloss finish painted walls. I insist on skim coating all drywall jobs now. Thanks Jay
This question used to come up every few months months 5 or 6 years ago. Haven't seen it in the last couple years?
It is as posted earlier dew point moisture attracting airborne pollutants.
Joe H
I think the Q becomes more common in winter, as wqith other condensation questions like , "Why do my insulated glass windows in my new home make frost and etness in this cold snap?" Or "My roof seems to be leaking over my bathroom on the north side all of a sudden when the weather turned bitterly cold"But I do see less of this phenomenon lately, probably because over the yuears better insulatrive packages are more common
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
The problems are related to four deposition mechanisms: filtration, electrostatic attraction, thermal deposition due to Brownian motion and impaction. These deposition mechanisms cause tiny microscopic airborne particles to:
+ "filter out" in carpets;
+ "plate out" on charged surfaces due to electrostatic attraction
+ "plate out" on cold surfaces due to "Brownian motion"; or
+ "plate out" on surfaces due to 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/index_html
The particle sources for the types of really tiny particles that can cause the problems observed are many:
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tobacco smoke
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candle smoke
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fireplace smoke
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pilot light smoke from gas fireplaces
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carpet smoke from carpet fibers pyrolysis on heat exchanger surfaces (when you vacuum, you throw up fibers into the air and these fibers get pulled into your furnace where they can get fried/cooked/burned on the hot surfaces in your home)
#
lint smoke from pyrolysis of lint in dryers that don't vent to the exterior, or don't vent well
#
incense smoke
# insulation smoke from insulation getting sucked into buildings or ductwork and pyrolyzing on heat exchanger surfaces
# gas smoke from gas water heaters or gas furnaces
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cellulose smoke from paper particles pyrolizing on baseboard heaters
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just plain old dirt - but really tiny dirt because it has to be able to float up in the air for a long time - typically clay dust from a nearby construction site - clay because usually only clay gives you the right size of particle that can float for a long time
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concrete dust from grinding mechanisms or concrete cutting
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gypsum board dust from sanding and finishing gypsum board
Probably condensation is also a factor in some of these cases. Likely there are several mechanisms, and which one dominates varies from one situation to the next.The main requirement is the very fine particles, though.
If your view never changes you're following the wrong leader
Thank you for thqt, and for the personal quote in your profile!;)
Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!
I had this same problem in a house built in 1993, painting didn't help. The fix? Removing the upstairs carpet and thoroughly cleaning/vacuuming the subfloor. The original construction site was heavy, red clay, which was tracked in every day and integrated into the OSB. Can't believe we didn't know we had so much dirt underfoot for 10 years. But now, no more ghosting for the last 5 years.
"ghosting" of studs on walls) post #114422)
I've only seen this on the walls of old houses that have been insulated decades after their construction with blown-in insulation in the stud cavities. Houses built before 1900+/- in my part of the country don't generally have building paper. Where buildings don't have paper, the paper has deteriorated from oxidation or there are avenues for moisture intrusion, the insulation gets wet, casuing dirt to collect on the stud cavities.