Killing Mold on Wallpaper?

Mold is beginning to form on our wallpaper down toward the bottom. It’s the tropical climate, I guess, but our previous place had wallpaper, and in seven years there, no mold. We’ve owned this one several years now, and it just started appearing a few months ago. The walls in question are all on the other side of one of the restrooms, so I guess the humidity from there may be contributing.

Is there a way to kill off the mold without changing the wallpaper?

Bleach water is where I’d start.
Assuming you feel the wall paper can take it with out getting bleached itself.

I’d reccomend:

  1. Check for leaks, something is making your wall moist.

If the waterpipes, drains, roof and outer walls are ok:

  1. Improve the ventilation on both sides of the wall, ideally bringing the humidity down and making the temperture the same on both sides of the wall.

then start attacking the visual evidence of the mold. On every occassion I had to deal with mold this ment replacing the wallpaper, but if you have really good wallpaper you might fare better.

Good luck!

Check for the source of the moisture. Mold is a symptom. The disease is a wet wall. If it hasn’t grown there in 7 years there is a new cause of a wet wall. Particularly if there is a shower on the other side, the source of the moisture is probably penetration of water into the wall and through to the side growing the mold, or possibly a pipe leak in the wall. Condensation on cold pipes in the wall is another possibility but should not have started now. Bleach kills mold but may ruin the wallpaper. In any case your mold is telling you you have a wet wall. Unless it’s a concrete wall, that’s a bigger problem than the mold.

Vinegar and/or borax will kill mold and shouldn’t hurt the wallpaper

Thanks to all.

Actually, that was our previous place that we’d had for 7 years; I was using that as an example of us having wallpaper but never any mold. THIS place we’ve had for 3 1/2 years, and the mold started about six months ago, so that means it started 3 years after we bought the place. We bought new, so we’re the original owners. Cold pipes are generally not a problem here in Bangkok; we usually get hot water even when it’s not turned to hot, because of the climate here, and although we have what they laughingly refer to as a cool season, it never gets cold; barely even gets cool, and that’s only in the wee hours of the morning, heating up again shortly after sunrise. (Our three seasons of cool, hot and rainy are often referred to as “hot, hotter and damned hot.”)

I’ve thought of leaky waterpipes, those are always causing problems in condos here, but the thing is the wall with the most problem is just a thin sliver of a wall separating the bathroom and bedroom doorways. The wall that originally started showing mold is a lengthy section on the other side of the bathroom, BUT the shower is all the way on the other side of the bathroom, away from that section of wall. Also, on all three sections of walls that have mold, it’s along the very bottom; if water were leaking from above, there would be mold above, yes? Or would there??

One other thing: The machinery for two of our air conditioners is up in the ceiling above the relevant sections of wall, so I thought maybe that was it. But we just had them serviced last weekend, and the workers did not see any water leaking. We did have a problem a couple of months ago with the bedroom air con suddenly dripping water through the vent in the ceiling, but that fell onto the floor and did not appear to enter the wall at any point; that was well after the mold had started anyway.

One person suggested that when they just finished building this place four years ago, they may not have let the wall dry sufficiently before putting up the wallpaper. But I think we’d have seen mold before three years if that were the case.

Borax. That’s a brand of powdered bleach, isn’t it? I’m not sure we have that brand here, but I’m sure I can find something similar. I’m a bit squeamish, though, about applying bleach to wallpaper, so I might try your vinegar suggestion. Thanks.

But like everyone has said, there must be water getting in there somehow. We’ll have our building’s maintenance people check inside the ceilings for leaks. Thanks again to all, and keep the suggestions coming, please.

Nah. It’s actually made of borax. :slight_smile:

It can be kind of harsh but I think that it would work. I’ll be really surprised if you can’t find it, at least somewhere that sells chemicals if not in the supermarket (where it’s definitely readily available in the U.S.).

Of course, there’s no harm in trying the vinegar first anyway.

We’ll pick up a bottle of vinegar this weekend (it’s not something we just happen to keep around), and I’ll get back to you. I hope the vinegar or borax works, because we’ve learned that the company that made this wallpaper no longer makes this design. Grrr. They have something close – it’s rather a simple design – but not exact.

Our building’s maintenance people have confirmed there are no pipes behind the wall where the mold is occurring; when they heard we had mold, they expected to see it down at the other end and were surprised where it really was.

By any chance is the floor tiled? I can see a tile floor in the middle of a humid night having condensation form. And I can see the moisture being wicked up into the paper and sheetrock.

If that’s the case, have the bottom of the sheetrock trimmed ever so slightly.

Water can end up far from where it gets in. A leak in the roof can easily trickle along beams and end up 20 feet away in a wall. Moisture is coming from somewhere, or there would be no mold.

The bedroom is carpeted. Outside the bedroom is some sort of fake wood paneling.

I’m starting to feel the air cons are the culprits, but I’m still not sure why no mold at the top of the walls/wallpaper.

The water can follow the stud down to the floor before it spreads out and touches the wall. Some walls have a vapor barrier that is water proof. The water can’t contact the wall until the water is past the barrier. Air conditioning drain pipes are notorious for getting plugged. The water then runs from the collector pan to watever is below it. Did they actually install a drain pipe for the air conditioning unit? find where the drain pipe exits the the building and try to blow air into the drain pipe. A compressed air source is recommended. Some times the blockage is at the drain pan exit, and sometimes a creature will climb into the pipe from the outside. A leaking toilet seal close to the wall can soak the wall. The water seeps under the tile, and gets to the wall, and seeps into the wall material.

As mentioned, we did have a problem with one air-con unit leaking a couple of months ago, and that was because of a blocked pipe in the ceiling. But the water all ran through the ceiling vent onto the floor … or so we thought. Now I’m thinking some must have made its way down the walls. The mold predates that problem by about four months, but the problem could have started back then without us knowing it.

The mold has also stabilized, it does not seem to be growing, so maybe that’s a sign that when we fixed the air-con problem, no more water was getting into the wall?

Well, we will try the vinegar this weekend and see what happens. If it comes to it, we can find the bedroom wallpaper, we discovered – at least, there’s a limited supply left, and we’ve had the condo office save us some – and there’s a type of wallpaper that’s similar to what we have in the living area.

Thanks again to all. The suggestions and comments have been very much appreciated, I assure you.

We tried vinegar this weekend, and the mold just laughed at us. We’ll look for borax. Seems to be harder to find than I thought, but we’ve been assured it can be had.

But now, looking behind the couch in the wife’s dressing room, we see mold on the carpet all along that side of the wall. !!! There are no pipes in that wall at all. This is rather bizarre. We’ve never had problems with mold before. Even in our previous condo, when the neighbors’ pipes broke and flooded part of our unit, everything dried out okay with no mold.

I hope you find the leak soon.

We’re having a heckuva time finding borax. I assume it’s this same borax here.

The grocery store near us found one employee who knew what it was, and he told my wife it had to be licensed as a dangerous substance, so they couldn’t carry it. Said he knew what it was because his grandfather used to clean gold with it and that we should be able to find some at a gold shop. (There are LOTS of gold shops in Thailand.) The cleaning lady in my wife’s office said she thought she could find it in her neighborhood, but a check of the gold and paint shops in her area (she said it’s used in paint, too) turned up zilch. My wife checked a gold shop or two near her workplace, but no. Someone else told my wife it should be in the supermarket, that it was a food additive and should be on the same shelf as baking soda and such. We’re thinking at this point, “What the …?”

I see from the link above, though, that it has industrial uses AND is a food additive, although looks like it’s outlawed in food in the US for food. But at least we know everyone’s probably talking about the same substance.

It’s sold in pharmacies, it is sold as an ant and roach treatment, it’s a laundry additive, and some other uses for the house.

Here is a thread on boric acid, which is likely the name you will find it sold as. It’s in a solid powder not a liquid. Borax is a brand name for a laundry additive sold in America, but it’s not the only source.

Please note that the use for wood treatment in this link says boric acid is a fungicide and insecticide. The fungicide properties are why it’s sold in a pharmacy.

You could also try TSP (trisodium phosphate, I think). You should be able to find it at building supply places. It got rid of mold in my basement, even took the stains out of cinder block.