# Mold Behind Wallpaper - Remediation



## joecaption (Nov 30, 2011)

So have you figured what what causing all these issues and addressed that yet?
No way would I be trying to save the drywall to save a few dollars.
Pulled some of the drywall off to see how they built out the walls?
Whole lot of things can be causing this.
Grading, outside of the foundation was never water proofed before back filling, lack of gutters with proper length down spouts, may need a french drain outside, dehumidifyer in the basement.


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## TheSrProgrammer (Mar 7, 2016)

joecaption said:


> So have you figured what what causing all these issues and addressed that yet?
> No way would I be trying to save the drywall to save a few dollars.
> Pulled some of the drywall off to see how they built out the walls?
> Whole lot of things can be causing this.
> Grading, outside of the foundation was never water proofed before back filling, lack of gutters with proper length down spouts, may need a french drain outside, dehumidifyer in the basement.


My theory is that the temperature differential in the room, which has a wood burning stove, caused the excessively warm air to rapidly cool at the surface of the drywall, forming water droplets/vapor behind the wallpaper. The issue then was that the wall wasn't able to breathe properly with the wallpaper covered in this vinyl wallpaper that was also painted. The combination of this moisture along with the gorilla snot wallpaper glue gave the mold a great place to take hold.

That's my theory at this point. I don't have any evidence that there is a downspout/flashing/caulking/roof issue. If you have any ideas for how I can check some of these things in greater detail, I'd be very appreciative.

-TheSrProgrammer


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## chemman (Apr 2, 2012)

I found something similar in my house. An interior wall that was used as a ventilation return had heavy vinyl wallpaper on both faces and I found exactly the same mold/mildew underneath when the wallpaper was pulled up. I assumed that same cause as you, the great temperature difference caused condensation under the vinyl. The area affected was fairly small so I cleaned up the bare drywall a bleach based spray cleaner. Take my advice as well as others, do not waste your time trying to save drywall. The time and effort difference, whether you diy or pay someone, between repairing and replacing is just too great. Plus you'll get the opportunity to air seal and upgrade insulation in exterior wall. Good Luck!


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## TheSrProgrammer (Mar 7, 2016)

chemman said:


> I found something similar in my house. An interior wall that was used as a ventilation return had heavy vinyl wallpaper on both faces and I found exactly the same mold/mildew underneath when the wallpaper was pulled up. I assumed that same cause as you, the great temperature difference caused condensation under the vinyl. The area affected was fairly small so I cleaned up the bare drywall a bleach based spray cleaner. Take my advice as well as others, do not waste your time trying to save drywall. The time and effort difference, whether you diy or pay someone, between repairing and replacing is just too great. Plus you'll get the opportunity to air seal and upgrade insulation in exterior wall. Good Luck!


I'm starting to question whether saving the drywall is an advisable approach as well. It's been some 24 hours and the drywall still has a moldy smell to it. I've been told I can use the Zinsser Perma-White product and that it should most likely be sufficient. The same person also said BIN from Zinsser should handle any of the smell.

At the end of the day, with the great investment in time and $$$ made, I want it done right. I don't want it to smell at all, and I definitely don't want a recurring problem of any kind. With that said, I have some concerns about replacing drywall.

1) I don't have a truck, and drywall sheets are rather large to transport.
2) I have never hung drywall before.
3) Replacing drywall behind the hot water heaters may be a real PITA. I don't even know how I'd manage to do that properly or how to get them detached from the drywall.
4) I'm concerned I wouldn't be able to start and complete the job in sufficient time to not expose the interior of the home to the elements - it's winter, you know.
5) If I open the walls and find a bigger issue, I'd be both glad and disappointed, and that is reason enough to make one pause for a moment. Hmm.
6) Referencing point 2, I'm quite concerned that the finished product will be below standard in what it should be. I'm anal as hell with my work, but I'm just not skilled at house repairs yet.

Basically, I'm afraid to go to that extent and remove the drywall, even though the evidence may support that being the better option. Hmm.


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## Gary in WA (Mar 11, 2009)

Welcome to the forums!

Could you describe the exterior wall make-up, please? Vinyl covering is a vapor barrier, as you found. Worse is not extending it down to the sub-floor or up to the ceiling- behing the trim- leaving avenues for interior air to mitigate. Where are you located? Is there another poly vb under the drywall? Wallpaper paste has organic material that does mold, as does the paper covering on the drywall (no way to completely clean it, IMHO).

Gary


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## TheSrProgrammer (Mar 7, 2016)

Gary in WA said:


> Welcome to the forums!
> 
> Could you describe the exterior wall make-up, please? Vinyl covering is a vapor barrier, as you found. Worse is not extending it down to the sub-floor or up to the ceiling- behing the trim- leaving avenues for interior air to mitigate. Where are you located? Is there another poly vb under the drywall? Wallpaper paste has organic material that does mold, as does the paper covering on the drywall (no way to completely clean it, IMHO).
> 
> Gary


The exterior is a field stone. See pictures.

Note that in the one picture you're seeing the top of the basement beneath the field stone, which is cinder block.

It may be of note that the mold seemed isolated to the one corner from at the top of the wall all the way down to the floor next to the door. That was the one section of mold. Then the other section on the wall had mold, but only beneath the window level, not above.


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## chemman (Apr 2, 2012)

I'm betting on air infiltration and/or lack of insulation causing the drywall in those areas to get very cold, causing condensation under the vinyl wallpaper. If you look into the hole you cut in the drywall, what do you see?


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## TheSrProgrammer (Mar 7, 2016)

chemman said:


> I'm betting on air infiltration and/or lack of insulation causing the drywall in those areas to get very cold, causing condensation under the vinyl wallpaper. If you look into the hole you cut in the drywall, what do you see?


I cut hole in the drywall and actually hit a little of the insulation backing, so there is some there. I'm not sure how effective it is though. It's just starting to warm up where I am in southeastern PA, so I may not be able to get good readings about how cold that wall is getting. I do have an infrared temperature meter to use if we do get a cold night.

I also am curious about looking behind the wall using a borescope. It seems many are quite cheap on Amazon. I was looking at one from DBPower with 2 million pixels and LED lighting for 20 bucks. The downside seems to be that the cord is floppy and not moldable. I think that may be a shortcoming that could be conquered with some sculpting wire twisted around the cable in a spiral fashion though. That might make it easier to control and better than using a dry cleaner hanger. Does anyone have experience with a borescope or any recommendations?


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## Bud9051 (Nov 11, 2015)

Somebody has to say this, so I will. Way too long for me to get involved. Good luck.

Bud


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## TheSrProgrammer (Mar 7, 2016)

Bud9051 said:


> Somebody has to say this, so I will. Way too long for me to get involved. Good luck.
> 
> Bud


I can be a bit verbose at times. I've put a lot of thought and effort into this, so my posts reflect that in length.


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## Bud9051 (Nov 11, 2015)

My apology, but unless someone speaks up to let the posters know we are all volunteers here and even though I like your title, I can't get involved in extremely long threads. 

I haven't read the thread, but the one point I was looking to make was vinyl or similar wallpaper materials can act as a vapor barrier and limit drying to the inside. I don't know what others have posted or if this is related in any way.

Next thread, bait us with the meat of the post and let the rest of the information come in later .

Best,
Bud


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## Gymschu (Dec 12, 2010)

I admire the lengths you have taken to take care of the mold issue. It is fairly common when removing old wall coverings especially those covering exterior facing walls. I will say though that all I've ever done is spray some bleach on the moldy areas, let it marinate, rinse and then repaint. Zinsser does make a mold killing primer, but it's pricey and I haven't had the chance to try it yet.


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## chemman (Apr 2, 2012)

TheSrProgrammer said:


> I cut hole in the drywall and actually hit a little of the insulation backing, so there is some there.


Are you talking something that looks like brown paper?


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## TheSrProgrammer (Mar 7, 2016)

chemman said:


> Are you talking something that looks like brown paper?


I think it was black, but definitely not moldy. I'm thinking of just using some duct tape over that cut out piece of insulation backing when I repair the drywall there. Does that sound reasonable?


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## chemman (Apr 2, 2012)

OK, sometimes the older stuff is black instead of brown. Sounds like the paper backing on fiberglass insulation. What you essentially had was two vapor barriers, the backer on the fiberglass and the vinyl wallpaper, back to back, trapping moisture in between. That or you're getting water intrusion around you window and door from rain. But nothing I see from pictures you posted screams problematic, but I am by far no expert on exterior construction. Does the rain regularly blow onto that side of your house? Any problems with unexplained water intrusion in the basement on that side? Personally I'm leaning towards my first explanation.


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## SeniorSitizen (Sep 10, 2012)

Possible results from an ice dam or dams 1,2,3 or more years previous is anyone's guess.

I'd be getting the dry wall off without hesitation.


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## TheSrProgrammer (Mar 7, 2016)

chemman said:


> OK, sometimes the older stuff is black instead of brown. Sounds like the paper backing on fiberglass insulation. What you essentially had was two vapor barriers, the backer on the fiberglass and the vinyl wallpaper, back to back, trapping moisture in between. That or you're getting water intrusion around you window and door from rain. But nothing I see from pictures you posted screams problematic, but I am by far no expert on exterior construction. Does the rain regularly blow onto that side of your house? Any problems with unexplained water intrusion in the basement on that side? Personally I'm leaning towards my first explanation.


 I think your first assumption seems reasonable, though I did ensure there was no mold on the back side of the drywall with a test cut over a particularly moldy area. The backside was clean as a whistle.


The outside conditions, as well as those in the basement, appear to be rather normal. What was abnormal was the kind of wallpaper. We had wallpaper in another room on the same side of the house, but those walls had a thin paper and not vinyl. There was no mold under that paper. The smoking gun is that wallpaper. Vinyl should not be used on outside walls. This is clear evidence supporting that.


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## Bud9051 (Nov 11, 2015)

Just wanted to reply to that conclusion, "Vinyl should not be used on outside walls.". In a heating dominated climate, if needed, a vapor barrier would indeed be installed on the inside. They even recommend a vapor retarder rated paint when a VB has not been installed behind the drywall. Your issue, my guess, is that the wall assembly was not able to dry to the outside and/or was subjected to more moisture than could dry through that direction. 

Your comment that the fireplace subjected the wall to excess moisture which formed behind the vinyl doesn't fit either as the vinyl should have prevented that.

If the wall assembly cannot be made to dry properly to the outside, then eliminating the vinyl and avoiding certain paints is probably the best you can do.

Best,
Bud


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## TheSrProgrammer (Mar 7, 2016)

Bud9051 said:


> Just wanted to reply to that conclusion, "Vinyl should not be used on outside walls.". In a heating dominated climate, if needed, a vapor barrier would indeed be installed on the inside. They even recommend a vapor retarder rated paint when a VB has not been installed behind the drywall. Your issue, my guess, is that the wall assembly was not able to dry to the outside and/or was subjected to more moisture than could dry through that direction.
> 
> Your comment that the fireplace subjected the wall to excess moisture which formed behind the vinyl doesn't fit either as the vinyl should have prevented that.
> 
> ...


I'm planning on using a 6" spackle knife to knock down any remaining knubs on the walls and then use a sanding pole with 120 or 100 grit paper to smooth it all out out. After that, I was planning on applying Zinsser Gardz to seal in the walls and any potential residue from the wallpaper paste. After some light sanding and patch work, I was planning on using Zinsser Perma-White to cover it all over.

The only thing I'm concerned about is the Gardz locking in the mold and creating a barrier much like the vinyl. I'm not sure how likely it is this causes a problem for me in the future. I could always go another route, the tried and true method, using an oil based primer. That might allow the walls to breathe better than the Gardz product would - I'm really not sure. I do know I don't want the nasty oil paint fumes though... I really don't care for that.

Does anyone have any thoughts on which route is better?


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## TheSrProgrammer (Mar 7, 2016)

Bud9051 said:


> Just wanted to reply to that conclusion, "Vinyl should not be used on outside walls.". In a heating dominated climate, if needed, a vapor barrier would indeed be installed on the inside. They even recommend a vapor retarder rated paint when a VB has not been installed behind the drywall. Your issue, my guess, is that the wall assembly was not able to dry to the outside and/or was subjected to more moisture than could dry through that direction.
> 
> Your comment that the fireplace subjected the wall to excess moisture which formed behind the vinyl doesn't fit either as the vinyl should have prevented that.
> 
> ...


Also, I think the excess moisture was able to get behind the wallpaper. The wallpaper didn't go to the floor in most cases and stopped right behind the top of the baseboard hot water heaters on the floor. I think this created a prime environment for heated air to get up behind there and mold up the place.

The one corner did have mold from floor to ceiling without the baseboard heating elements though. I actually have a small endoscope camera coming in today, so I'm going to more likely than not poke a hole in the wall and see what I can find.


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## Bud9051 (Nov 11, 2015)

You have the advantage on me in that you are there and it sounds like you are giving all factors good consideration. More reading is always good, note the additional material listed to the right at this link.
http://buildingscience.com/documents/building-science-insights/bsi-091-flow-through-assemblies

Bud


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## chemman (Apr 2, 2012)

I'm going to guess that the wallpaper was applied to the raw, unprimed drywall, from the looks of the pictures you posted. What you are mostly likely to run in to is the paper on the drywall will bubble up badly when you hit it with the Gardz. My foray into DIY started the exact same way. Your only recourse is to cut the bubbled up paper out and apply more Gardz. This process repeats itself until you think you've got all the bubbles, but now your wall looks more like swiss cheese. Now you've got to skim coat the wall, sand smooth, and apply Gardz (or primer) again to get an even finish and completely seal up the wall so the mold/mildew is locked away forever. For a first timer this kind of drywall work is time consuming (especially if you're a little OCD), messy, and tiring. If you pay someone else it will cost more than tearing out and replacing. And when it's all said and done, you'll still have substandard insulation and excessive air infiltration, just because most homes are built that way, especially older ones like yours.



> The only thing I'm concerned about is the Gardz locking in the mold and creating a barrier much like the vinyl. I'm not sure how likely it is this causes a problem for me in the future. I could always go another route, the tried and true method, using an oil based primer. That might allow the walls to breathe better than the Gardz product would - I'm really not sure. I do know I don't want the nasty oil paint fumes though... I really don't care for that.


Since the Gardz or oil based primer will be tightly adhered to the wall, moisture will not be able to get under it and condense. If anything it'll condense on the face of the wall instead. That fan setup you've got should make short work of any fumes and construction dust.


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## chemman (Apr 2, 2012)

By the way, are you closer to Philly or Allentown?


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## TheSrProgrammer (Mar 7, 2016)

chemman said:


> By the way, are you closer to Philly or Allentown?


Basically right in the middle close to Doylestown. City is about 45 min, and so is Allentown.


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## Gary in WA (Mar 11, 2009)

IMO, you only have one vapor barrier, the vinyl paper;, the *facing *has a perm rating of 0.4 perms, a vapor* retarder*. The moisture is coming from the exterior, probably in the summertime and stopping at the wallpaper, especially if running ac or cooling furnace fan; http://buildingscience.com/documents/reports/rr-0410-vapor-barriers-and-wall-design/view

Under the window as that is the block wall absorbing moisture with no framing above to "throttle" it to dry...

IMO, tear out the drywall as the "gaurdz" is a low perm retarder- or vapor barrier- check lit., as is the paper facing.

Gary


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## larsonreever (Mar 9, 2021)

Indeed, it is estimated that roughly 40% of canadian buildings have some form of mold or toxic mold. In this statistic, it’s believed that these dangerous mold spores are present in an alarming 25% of homes in the toronto alone!

Certain structural defects in a home can let in excess moisture, create a nutrient-rich environment, or otherwise produce an environment that is ideal for mold.

A growing body of researcher has started to find evidence that wallpaper can be a significant source of fungi such as mold. Many of which can produce toxic indoor air pollution. Five studies found three different types of fungi living in household wallpaper.

This included:
*Penicillium Brevicompactum*

If you believe that the wallpaper in your home is promoting mold growth, you should strongly consider having it removed. If the problem is significant, you should turn to a professional mold remediation service with the right tools, training, and experience to effectively eliminate the presence of mold from the home or building.

In a less severe case, you might be able to remove the affected wallpaper yourself. There are some important DIY mold removal toronto steps you should take to do it safely and effectively.


You should also seek out a respirator mask that is rated for to screen out microbes. Protective eyewear is also a very good idea, as are latex gloves. Some types of mold can cause severe skin irritation.
It’s also a good idea to remove all furniture and clothing from the room and keep the door shut.Carefully peel away a small strip of wallpaper.
Carefully remove all the wallpaper from around the affected area.Prepare a cleaning solution that is 4 parts dimethyl ammonium chloride with 1 part of water.
Carefully brush the solution over the mold. Allow the treated area to thoroughly dry before cleaning it with soap and water


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