Black Mold

[potter]

We are looking at a house to buy. Nice place, early 50's ranch. Upstairs seems fine,not moldy, but block basement perimeter is black mold about 6-8 inches from the floor. Is this something fixable? Should we back away as carefully as possible? If it's fixable, what cost would you guess? About 1800 sf house.
Place was family built, unmarried son after parents died, little maintenance or attempt to address the issue that I can see. Being sold by the estate. We have a three year old and my wife is pretty sensitive to molds. Upstairs does seem perfectly fine. No standing water in basement, but built into a probably clay hillside, so seems like it has just saturated the block. Basement is unfinished so no framing, wood at base that can't be removed. Floor joists seem dry and free of mold (visually), really limited to floor level. Any thoughts would be appreciated.

 

[smokinj]

I would have it inspected. Its hard to say without knowing exactly whats going on.

 

[peakbagger]

Getting a mortgage with mold present is going to be an issue, if it is a drainage issue, you need to get if fixed before moving in. I would suspect that the blocks fill up with water from the outside at some point in the year and it seeps in through the block. which causes the mold condition. There are some interior fixes where they drill the blocks at the base and then dump them in a trench to a sump, better than nothing but the real fix is to excavate and install drainage fabric and proper drainage. Note most insurance policies these days specifically exclude mold issues. Alternatively it could be a indication that the basement floods on occasion.

I havent had it done but long ago someone said about 5 K for B-dry install. The outside fix on is very dependent upon access, if its is good a backhoe can get the wall excavated in a day, then a day to pressure wash and install drainage fabric and a day to back fill. I would consider insulating the wall while you are at it. Pure swag would be less than 10 K. Get a contractor to take a look at it get a written estimate and counter to the estate to subtract this repair from price or make sale conditional on fix.

 

[semipro]

+1 on what PeakBagger said.

Also, earth movement is not covered by most home insurance. If there's moisture getting in then movement of that hillside is definite possibility. I've know two instances where basement block walls collapsed and were not covered by insurance.

I wouldn't want to live there unless the uphill side of the foundation was excavated and properly water sealed with a vertical drain layer against the block and french drain beneath. I'd also want to make sure that the walls had vertical re-bar reinforcement and that the voids were filled around the re-bar with mortar.

 

[gzecc]

Call Servpro http://www.servpro.com and get an estimate

 

[dave11]

Mold on the block walls of a basement is very different from mold on wood, or mold in concealed places. Mold just means a surface is wet, at least some of the time, and doesn't get much sunlight.

The mold might be from moisture in the air condensing on the cold block walls. You might not have any significant water actually coming through the wall.

Is the mold worse in the all the corners of the basement?

What is the grade around all four sides of the house?

 

[potter]

Thanks for the responses. We could pay cash, and if I thought it was do-able, might make the place go cheap if others couldn't mortgage. WNY is cheap real estate by national standards- property taxes, though....
The block all looked sound and straight. The mold seemed to be coming up from floor level as I said, but I would have it inspected. Seems like the perimeter excavation would be the real answer. Just want to make sure when said and done any existing mold would survive.

 

[potter]

Mold on the block walls of a basement is very different from mold on wood, or mold in concealed places. Mold just means a surface is wet, at least some of the time, and doesn't get much sunlight.

The mold might be from moisture in the air condensing on the cold block walls. You might not have any significant water actually coming through the wall.

Is the mold worse in the all the corners of the basement?

What is the grade around all four sides of the house?

Mold seemed equal around entire interior perimeter, worse in a couple of closed off cellar rooms.
As I said it's built into a pretty steep hillside, so I would think sides and front would be well drained? Again it was damp and humid, but didn't see any evidence of former flooding or standing water. I've got some pics, but don't know how to post them.

 

[potter]

Call Servpro http://www.servpro.com and get an estimate

Boonies- nothing comes up for my zip.

 

[dave11]

Mold on the block walls of a basement is very different from mold on wood, or mold in concealed places. Mold just means a surface is wet, at least some of the time, and doesn't get much sunlight.

The mold might be from moisture in the air condensing on the cold block walls. You might not have any significant water actually coming through the wall.

Is the mold worse in the all the corners of the basement?

What is the grade around all four sides of the house?

Mold seemed equal around entire interior perimeter, worse in a couple of closed off cellar rooms.
As I said it's built into a pretty steep hillside, so I would think sides and front would be well drained? Again it was damp and humid, but didn't see any evidence of former flooding or standing water. I've got some pics, but don't know how to post them.

If the mold is distributed roughly throughout the basement, all the more reason to believe its not coming through the walls. If it were along one wall, say the wall with the worst outside grade, then it'd be more likely to be coming through the wall.

More likely its humidity in the basement air condensing on the cold block walls. A dehumidifier and some bleach would be the answer.

 

[midwestcoast]

I can't help much on the fix, but just had the thought before you jump in you might want to take your wife into the house & see if she how she reacts to the mold. There are very few species that are actually dangerously toxic, but if she is sensitive to the species in that house you may never be able to get it clean enough for her to be comfortable living there.

 

[Danno77]

Mold on the block walls of a basement is very different from mold on wood, or mold in concealed places. Mold just means a surface is wet, at least some of the time, and doesn't get much sunlight.

The mold might be from moisture in the air condensing on the cold block walls. You might not have any significant water actually coming through the wall.

Is the mold worse in the all the corners of the basement?

What is the grade around all four sides of the house?

Mold seemed equal around entire interior perimeter, worse in a couple of closed off cellar rooms.
As I said it's built into a pretty steep hillside, so I would think sides and front would be well drained? Again it was damp and humid, but didn't see any evidence of former flooding or standing water. I've got some pics, but don't know how to post them.

If the mold is distributed roughly throughout the basement, all the more reason to believe its not coming through the walls. If it were along one wall, say the wall with the worst outside grade, then it'd be more likely to be coming through the wall.

More likely its humidity in the basement air condensing on the cold block walls. A dehumidifier and some bleach would be the answer.

Bout two years after we moved in we noticed some mold on our field stone walls in the basement. Got a dehumidifier, sprayed the crap out of it with a bleach water mix. That was about 4 years ago, still clean as a whistle. Don't even use a dehumidifier anymore, the house sat unconditioned for so long that I think that was part of the problem. When was this house last occupied?

 

[Cazimere]

When i bought my place 20 years ago, i got the seller to knock 10,000 off the price because of black mold on the paneling in the sun room. I scrubbed it all off with a 50/50 solution of white vinegar and water with dish soap. When done i sprayed it with straight 5% white vinegar. Mold has never come back.

 

[SolarAndWood]

My current house had 2 sump pumps and a just installed $5K lifetime guaranteed waterproofing system when we bought it. Made no difference, basement was still wet. After full excavation of the downhill side of the house, 20 yards of stone and running all the drains to daylight, it is bone dry. Last house just needed two downspouts fixed and very minor grading work done to solve a decades old problem. Anything can be fixed, just depends on how much needs to be done and whether or not it is worth it to you. Either way, you need to address it at the source of the water because you can't fight the river.

 

[potter]

Attempt at picture.

 

[potter]

Let's try again, having trouble getting another image through.

 

[potter]

And one more, since I seemed to have managed this...

 

[Danno77]

After seeing the pics, I think the people here have covered the likely cause as too much moisture, maybe coming from outside the foundation due to poor drainage.

I don't think this looks like an out-of-control situation. I'd take a good look outside at drainage and fix anything that's needed. clean it as well as I could using methods mentioned above, and keep it dry with a dehumidifier. I know they make anti-mold paint, but I'm not sure if they make one that is appropriate for masonry surfaces. You should explore that.

 

[Sisu]

As people have said, look at your outside drainage. The mold could be an indicator of drainage issues. It could be as simple as redirecting/extending your downspouts, re-grading the soil around the house perimeter, etc. Do you have eavestroughs?

Typically, black mold is indicative of stachybotrys. It is the genus of mold that is more problematic for people's health. Usually, it does not typically grow on concrete, since the concrete is not a favourable growth medium. However, if the moisture is from surface water (eg. rain), the runoff is carrying organic materials that are perhaps providing food to the mold. Sometimes the dangers of mold are overblown, but there are people who are more sensitive to mold exposure (via airborne spores).

I would check the rest of the house for mold issues. Look at the drywall walls and ceilings, carpets, attic, etc. for any indicators of moisture, mold, water leaks, floods, etc. Also, use your sense of smell. Is there a mold smell throughout the house? If the mold/water problems are not limited to the basement, you might want to walk away for buying this house.

If it looks like an easy fix and you are not sensitive to mold, you can use the issue to bring down the price of the house. If it is an issue of drainage that can be fixed easily, fix the problem and then clean up the mold. Get a half-mask respirator with P100 filters, close and seal the door to the basement (so the mold spores won't travel to the rest of the house), and scrub the mold out with bleach water along with all the other surfaces in the basement. Use a dehumidifier to control the basement humidity.

 

[semipro]

That photo leads me to believe either:
1) A french drain was installed but was installed too high. It should be below the top of the slab or;
2) A french drain was installed but gutter downspouts are (wrongly) flowing into it or;
2) That block wall was not sealed well outside and water is flowing through the outer wall and into unfilled core openings and collecting in the bottom or;
3) Water is wicking up the block from below somehow.

 

[dave11]

The presence of mold doesn't prove there is any water coming through the block walls. Moisture already in the air outside, that gets into the basement from having doors/windows open or any air leaks, can then condense on the block walls, which are always going to be cool during humid summer months. That will cause mold, especially in the corners.

 

[semipro]

The presence of mold doesn't prove there is any water coming through the block walls. Moisture already in the air outside, that gets into the basement from having doors/windows open or any air leaks, can then condense on the block walls, which are always going to be cool during humid summer months. That will cause mold, especially in the corners.

If this was in response to my post.

Agreed. The poured concrete walls in my basement demonstrate what you say if we don't dehumidify.

However, my observations above are based on the photo and the way the mold is distributed along the bottom of the block wall. You rarely see that sort of pattern when dealing with mold fed by airborne water.

 

[semipro]

Deleted duplicate

 

[potter]

Thanks for the help and comments!