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#1 |
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Pro
Trade: Deck Builder
Join Date: May 2007
Location: Indiana
Posts: 311
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Dark Marks On Walls
This is in a stairwell. The walls were precast concrete panels. The stairwell was considerably cold, so they decided to fir out the panels with metal studs & put board insulation between them & attached drywall to the metal studs. First winter they got these dark lines. It wipes off on your fingers if you rub it. I'm thinking condensation coming through the metal suds & drywall & attracting dust.
Anybody have any ideas what can be done to cover this up & prevent it from reoccurring. Thanks, Dan |
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#2 |
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Curmudgeon
Trade: carpentry/remodeling/"Yes M'am we do"
Join Date: Apr 2006
Location: Beech Grove, Indiana, Birthplace of the "King of Cool"
Posts: 11,707
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Re: Dark Marks On Walls
It's called thermal bridging.
One can try an oil base stain blocking primer, but I'm not sure if it will be a permanent solution. Try Google.
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Put your location in your profile! (Sorry....it seems there really are dumb questions) |
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#3 |
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Pro
Trade: Plastering, Drywall, Painting, Woodworking, Stucco
Join Date: Jun 2006
Location: South Eastern Michigan outside of Detroit.
Posts: 1,592
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Re: Dark Marks On Walls
we just wash it down with TSP in spray bottles you can get at Home Depot, spray it wipe it down then prime Benjamin Moore's Freshstart Primer then paint two finish coats of paint. Good luck
www.frankawitz.net |
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#4 |
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Pro
Trade: Masonry consultant
Join Date: Nov 2006
Location: MSP, Minnesota
Posts: 2,446
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Re: Dark Marks On Walls
The real problem is the thermal bridging or "short circuiting" caused by metal studs. They kill or cut many insulation in half and all the heat loss is where ther occur.
That is the cause and you can try all the surface applications, but if the is any moisutre in the air, it will be attracted to the surface where the stud is. The slightly high moisture content on the surface, the more dust what will be attacted. The moisture and dust are in the interior no matter what the coating is. Whatever you put on the surface, is just a band-aid and not a real solution.
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Dick Engineer, designer and consultant recently active domestically and internationally on construction and design in about 35 countries. |
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#5 |
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Member
Trade: Painting Contractor
Join Date: Dec 2008
Location: Kentucky
Posts: 41
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Re: Dark Marks On Walls
If the residue feels kinda soapy or sticky it could be the surfactants (soap Stuff) in the paint itself. Can be cause by temp. change and moisture. Rub a little water on it and if it suds or bubbles up ---thats it.
Cure wash down the walls with soft sponge and a mild detergent. |
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#6 |
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Pro
Trade: Historic Restorations
Join Date: Feb 2005
Posts: 283
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Re: Dark Marks On Walls
Sure looks like Thermal Bridging .Check out this site http://www.inspect-ny.com/interiors/ThermalTracking.htm
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#7 |
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A bit abrasive.
Trade: Painting
Join Date: Sep 2008
Location: KC KS/MO
Posts: 1,529
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Re: Dark Marks On Walls
I hate to tell you this but every time you finish cleaning the offending lines off, someone arrives about 45 minutes after and draws the lines back onto the wall.
Next time clean the lines as you normally would and then hide...when said person arrives confront them and tell them how much it upsets others when they reapply the lines to the drywall. Hopefully they will see reason and stop doing it. Please no PM's, I have had a long day.
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My advice: Hire a real painter to do it. |
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#8 | |
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Member
Trade: Painting Contractor
Join Date: Dec 2008
Location: Kentucky
Posts: 41
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Re: Dark Marks On WallsQuote:
I like that website |
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#9 |
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Pro
Trade: painting
Join Date: Mar 2008
Location: Frankfort, KY
Posts: 109
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Re: Dark Marks On Walls
I have also seen this with fireplaces that are not vented properly. Not sure what happens but have seen it a handful of times. Once the homeowner fixed the ventilation problem and primed and painted it didnt come back
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#10 |
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Pro
Trade: Deck Builder
Join Date: May 2007
Location: Indiana
Posts: 311
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Re: Dark Marks On Walls
So, Thermal Bridging is what it's called, seems like I was correct with my diagnosis. I figured there was no solution to the problem, only bandaides.
What about tearing off the drywall, installing 1/2" foam board or fanfold & then putting up some new drywall? This would at least give it a thermal break except for the screws. P.S. Just to clarify, I didn't do the work. Was just asked to look at it. Last edited by Danno6102; 12-23-2008 at 11:37 AM. |
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#11 |
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Pro
Trade: Historic Restorations
Join Date: Feb 2005
Posts: 283
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Re: Dark Marks On Walls
Is this the only area in the house that this is happening? If so foam should stop it but it will show up on the screw heads. If it is in more areas of the house don't rule out an exhaust leak from a gas heating source. The gas company can us a sniffer to source the leak. Good luck
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#12 |
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Pro
Trade: Masonry consultant
Join Date: Nov 2006
Location: MSP, Minnesota
Posts: 2,446
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Re: Dark Marks On Walls
The foam does not stop the thermal bridging unless it totally separates the drywall from the wrinkled tin studs.
The studs transfer the heat because of the very high conductivity of the steel. The drywall is usually in contact with the stud faces, so the shortcircuiting is transfered to the dry wall. Since the dry wall has slightly less conductivity, it does not spread to the sides very far, so the cold spots on the wall will be a little wider than the stud face width. It is a classic situation and you can even see it with wood studs. As an example how bad the steel studs are, A 6" steel stud wall (at 12" o.c.) reduces the effective valuse of the R19 insulation to give you a R11 or so for the wall.
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Dick Engineer, designer and consultant recently active domestically and internationally on construction and design in about 35 countries. Last edited by concretemasonry; 12-23-2008 at 01:12 PM. |
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#13 |
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Member
Trade: Painting Contractor
Join Date: Aug 2008
Location: Boise, Idaho
Posts: 86
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Re: Dark Marks On Walls
Good post. I've only seen that once or twice over the years but never knew the technical name for it. Thanks
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#14 |
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Pro
Trade: Painting Contractor
Join Date: Feb 2007
Location: Huntsville Alabama
Posts: 1,349
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Re: Dark Marks On Walls
About time you decided to make your first post lol.
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Sean |
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#15 |
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I'm a Mac
Trade: ICF Construction
Join Date: Apr 2007
Location: Hog Town
Posts: 3,248
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Re: Dark Marks On Walls
If you can, use a thermal imaging camera (you may be able to borrow one from the local utility company) and snap a picture, now show the client and let them know what Concretemasonry said.
Heat the area and good chance it disappears.
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Chris |
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#16 |
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Pro
Trade: siding
Join Date: Mar 2007
Location: west milford n.j.
Posts: 8,851
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Re: Dark Marks On Walls
that mold website is cool
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#17 |
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Pro
Trade: Plastering, Drywall, Painting, Woodworking, Stucco
Join Date: Jun 2006
Location: South Eastern Michigan outside of Detroit.
Posts: 1,592
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Re: Dark Marks On Walls
I like the website, very infromative, Thanks for the link. I would think that if the tranfer of heat is lost that much, That the steel stud manufactures would apply a foam strip like sill seal on the edges to stop the steel stud from transfering the cold along like conductive heating. this would stop the Ghost lines, Like with the spray foam it seals everything.
www.frankawitz.net |
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#18 | |
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Member
Trade: Painting Contractor
Join Date: Aug 2008
Location: Boise, Idaho
Posts: 86
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Re: Dark Marks On WallsQuote:
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#19 |
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Dmax Consulting
Trade: Paint Contractor
Join Date: Jul 2008
Posts: 84
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Re: Dark Marks On Walls
I've never heard of thermal bridging until this. I learned something new today.
Happy new year! |
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#20 |
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Side Effects May Vary
Trade: Professional Painting
Join Date: May 2007
Location: Fort Wayne Indiana
Posts: 1,654
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Re: Dark Marks On Walls
It could be a sign of paranormal activity.
Use the lines as a guide and paint stripes down it,then it will not be noticed. |
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