I would see what the dehumidifer does with your moisture level. Then I would wait awhile before making the determination of mold. Does the substance re-appear now that you are dehumdifying? Did you use a mold test kit? Try those first if you suspect mold.

I didn't have the hose hooked up to the dehumidifier so it filled and didn't do much yesterday. I notice more of the substance on another wall today. I got the hose hooked up to the dehumidifier this morning and its dropped to 60%. I have it set to 50%. In the area where it was wiped, the substance has not come back.

This is my first home and I'm just scared and don't know what to do. I have been looking on the internet about mold and its got me worried. I don't know if I should clean it from the walls, or have someone test it?? I also noticed that on 2 of the walls where the substance is, the carpet is damp which I hadn't looked at carefully enough yesterday. I don't think anything is leaking, but maybe its damp from humidity or maybe the seller cleaned it. The other weird thing is that the "mold" is on some interior walls in the basement where carpet is dry. I did buy a test kit, but you have to mail it in so I don't know how much good it will do me.

Was this home inspected?
How long ago?
How much rainfall since then?

Hi cearbhaill,

Yes the home was inspected about 5 weeks ago. There was no mold at the time, but I suppose the owner could have wiped it away (like I did today). It just looks like greenish wet spots. There has been a good amount of rain since then. I am in Michigan, and it went from colder weather to hot and humid really quick. I talked with one of the neighbors and he said that their basement is damp as well so it might be the area I'm in.

I wonder if it could be mildew?? Today I had my Dad come over and we took off the molding and pulled he carpet near the areas that looked like mold was starting to show up. There was really nothing much behind the molding, just a few small green spots on the wood molding. Nothing was under or on the carpet either. Its concrete and there were no signs of water ever being there. It was completely dry. We also went on the back side of a part of the drywall to see if any mold was visible - nothing. I felt around on the drywall and it was solid, didn't feel soft at all. The original owner had a vapor barrier behind the drywall near the exterior walls.

The humidity is down to 55% today and it smells a lot better. I guess I am just going to wait and see if the "mold" appears again. I don't know what else I can or should do at this point. There was one area I didn't clean. I'm debating if I should get it tested or not. It did not appear to have characteristics of black mold, but I would just feel better if I knew whether or not it was some other type of toxic mold.

Here is a before pic.....I used Mold Armor to wipe it up. It looks wet, but its not wet at all. Like I said, I did touch it at first before I realized it could be mold and it was chalky. Should I get it tested?

There was no dehumidifier in the basement for about 3 weeks and I think the moisture started to build up. When I took the molding off there wasn't really much of the substance behind the molding, mostly just above it.

Here is a link that might be useful:

Mold and mildew are both fungi although some reserve the use of the term mildew for fungi on fabrics.

Mold will occur anyplace with moisture, no sunlight, poor ventilation and a food source (like cellulose). If there is a light powder coating it usually means there is a remote source of mold somewhere in the basement and the spores are being carried through the air to all surfaces that offer a food source.

Get the humidity down and search for a hidden mold source.

Ok, so I have talked to a few people and here is what I think may have happened. I had the inspection on April 27th. I closed on May 20th. When I closed I smelled a musty odor that I hadn't smelled before but assumed it was because it was warmer out. Last weekend I noticed that the water in the sump was about 3 inches from the top. I had the sump pump replaced because there was an issue with the switch or something.

Long story short, I think the sump may have backed up through the floor drains sometime between the inspection and closing. It makes sense because there are 2 floor drains near the walls that have the most mold growing...and the carpet was also slightly damp. I think the drywall may have absorbed moisture from the carpet. The only thing that doesn't make sense is that its not wet near the sump and there is an area between the carpet and molding that doesn't look moldy either.

If this is the case, can I salvage the drywall by cleaning it with bleach and using Kilz or do I need to cut it out?

I'd cut it out so you can address any issues behind it as well as let things dry out.

You'll want to kill the mold before it dries out as it's the airbone particulates that are unhealthy. In your case it's minimal so I wouldn't worry too much about it being enough to be an issue, but always best to be as safe as possible.

Well I think I will finish the clean up. Maybe wait a week or 2 and cut out a piece to check the back side of the drywall. If its on the front, I'm guessing its on the back too. I don't see evidence of standing water or that the drywall was ever even wet. ;-( I wonder why there is no mold on the carpet??

The mold seeks out organic materials to feed on. If the carpet is synthetic the paper facing of the drywall would be more attractive although the carpet backing might eventually be attacked by mold.

Thanks for all the posts everyone. As a first time homeowner this site is very helpful (I've been browsing other areas too).

You're going to be fine! Lower the humidity. Keep and eye on the sump pump. See if it becomes a problems. Most mold/mildew seems curable once the source (in this case the likely back up of the sump and some seepage) is removed.

If you do remove any drywall here are two tips.

Wear a dust mask, the ones that look like a surgeon's mask that you get at the hardware. Either read the labels or ask the clerk and tell them why you need the mask. They all look similar but there are various degrees of filtering and usage.

Last, you can carefully pop off your baseboards and cut rectangular inspection holes such that the repair is covered by the replaced baseboard. You don't get as large a view but your nose and a flashlight will tell you if you can just button it back up or if you need to remove more drywall.