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Discussion Starter · #1 ·
Hi all,

I just joined but wanted to share my experience with mold behind wallpaper and where I'm at with the project.

Some background:
We moved into our house a little over 2 years ago. The inspection report noted some mold in the bilco door stairwell in the basement. We had this professionally remediated, including the removal of all of the drywall along that back wall of the basement and the carpet. It cost $4K, and I wasn't that impressed with the work. They left he basement steps full of glue and staples, and I don't believe they used the proper containment methods after learning more about the industry standards...

Anyway, for probably about a year after that I complained that I could still smell some mold in the house, particularly in the living room. I'm not really sensitive to it allergy wise, but I don't like the smell at all and knew I smelled something. Nobody else was really smelling it though, so I ultimately let it go each time I brought it up. Well, that's until I realized the wallpaper peeling behind one of the reclining chairs against the outside wall.

I pulled back the wallpaper and was instantly hit with a rambunctious MVOC orgasm. And the visible mold was unsettling, to put it mildly. I pulled back some more paper in another area and found more mold. Pretty much every area along the outside wall had some mold behind the wallpaper. I pinned back the wallpaper and gave some thought about what to do and decided I was going to take the money I would normally pay to a remediator and do the job myself.

The first thing I wanted to confirm was whether the mold was on the other side of the drywall or if it was contained just behind the vinyl wallpaper which was also painted - which meant it did not let that wall breathe at all. So I used some Concrobium Mold Control from Home Depot on a section that looked pretty bad, effectively killing the mold in the general location and then cut a small hole with a hand powered jab saw. I was able to confirm the other side of the drywall did not have mold growing on it. This left open the possibility of saving the drywall, although many remediators will not suggest such a thing. The IICRC S520 (yes, I've read it) for the most part plays it safe and suggests removing anything that isn't a non-porous surface if it has visible mold growth. This approach is ultra conservative and most certainly leads to many remediation jobs being more extensive than necessary.

Here is a list of the things I purchased for the job:
Abatement Technologies Predator 750 air scrubber
10" diameter 24' long Heavy Duty Flex Ducting
Locking clamp for Flex Ducting
10" Powder Coated Inlet/Exhaust Collar for Flex Duct
Pullman-Holt 45 wet/dry HEPA vacuum
Set of 4 10' zip poles
1 gallon of Concrobium Mold Control Disinfectant - Professional
Concrobium Mold Stain whitening agent
North Safety 7700 series Respirator
North 75SCP100 Combination Gas and Vapor Cartridges
2XL Tyvek suit
DIF Wallpaper Remover
3.5 mil 10'x25' plastic sheeting
.7 mil 9'x15' plastic sheeting x 3
Disposable yet absorbent painters' throw - 4'x15'
Disposable Nitrile gloves
2 Garden Sprayers
1.88" thick Masking Tape
Paper Towels

With these things I was able to set up containment in the room and tackle the job. I used the 10'x25' plastic sheeting to setup the wall for the containment with the zip poles. I then used the masking tape (3 days safe to pull without damage) to seal the edges around the ceiling, side walls, and floor. I then setup the floor to be covered with the .7 mil plastic. This plastic is very flimsy, but I utilized the plastic on the floor in this combo: 1 layer of plastic taped on top of the hot water heater elements and the basement, the absorbent painters' throw, and then another layer of plastic on top. This may be overkill, but I didn't want the wood floors to get wet.

I hooked up the air scrubber to exhaust air from within the containment (the side where I was going to be working) out the window. The result was a room under negative pressure. A good way to tell that you have a negative pressure is to look at the plastic and see which direction is being blown. When you are in the room that is experiencing negative pressure, the plastic will be sucked/blown toward you. This is because air is leaving the room faster than air is being replaced. This results in air from the other side of the barrier trying to rush in to the work space to displace that lost air. This is a safer way to do this kind of work because you wouldn't want air flow to be blowing into the other areas of the house should the containment fail for some reason. If the containment failed, the air from within the house would be blown into the work area and quickly exhausted outside. Note that changing pressures within a home can starve other appliances that require a draft to operate properly. If possible, it may be a good idea to turn these appliances off (boiler, wood burning stove, etc.) to avoid issues with carbon monoxide. It’s better to be safe than dead.

I then removed all of the wall paper and used the DIF in a garden sprayer to remove all of the mold soil and top layers of wallpaper glue. I used paper towels to wipe the walls clean, removing much of the mold in the process. I followed up with a nice soaking of the Concrobium Mold Control Disinfectant. I followed up yet again with the DIF, along with another soaking with the Concrobium Mold Control.

I did this all yesterday. Right now I have the room still setup with the containment in place and the air scrubber doing its job exhausting air outside. Today I plan on HEPA vacuuming the area to get all the flakes and nonsense that came off the walls. I then plan on using a putty knife and some DIF to remove the remaining and stubborn wallpaper glue – it must have been applied with Gorilla snot.
I will try to post some after pictures to help all see how far it has come. I do hope this may help some others who may fear going through so much to do the job yourself. If I can do it, anyone can.

-TheSrProgrammer
 

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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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Discussion Starter · #3 ·
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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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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Discussion Starter · #5 ·
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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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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Discussion Starter · #7 ·
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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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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Discussion Starter · #9 ·
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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Somebody has to say this, so I will. Way too long for me to get involved. Good luck.

Bud
 

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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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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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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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Discussion Starter · #18 ·
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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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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Discussion Starter · #20 ·
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
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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