White mold on basement joists


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Old 03-12-20, 03:27 PM
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White mold on basement joists

There is some white mold on the floor joists in the basement which has spread a little over the winter and I want to prevent it from becoming a bigger issue. What is my best course of action to remove it and keep it away. Humidity is controlled, and there is an air purification device running for the record. I had thought about getting a mold killing primer and painting all of the joists. Is there any reason I shouldn't do this? And are there any other solutions anyone would suggest? Thank you.
 
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Old 03-12-20, 04:25 PM
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If you are having mold growth your humidity is not under control... at least as far as getting it low enough to prevent mold growth. You could spray a mold killing agent on your joists and subfloor but I wouldn't paint them. I'm not sure what affect having a pseudo moisture barrier on the bottom of your floor might have. I would hate to trap moisture in the wood during winter.
 
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Old 03-12-20, 06:19 PM
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Any recommendations on what to use? Can I get away with anything natural like a vinegar mixture?
 
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Old 03-12-20, 07:10 PM
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I would use hydrogen peroxide. You can then use a putty knife and hepa filter shop vac to clean it up. I also wonder about the comment you made that "the humidity is under control". If it was, there wouldn't be mold. Humidity needs to be below 50% to keep mold from actively growing. You can wear an N95 mask to do this, but if you prefer a half mask that's probably better.
 
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Old 03-12-20, 07:45 PM
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Thanks for the reply x sleeper. I had a device installed that is supposed to render a dehumidifier useless while also purifying the air. The humidity level was set at less than 40%, however when I started to run a dehumidifier about an hour ago it read a level of 56%, so this must be part of my problem. How would you apply the Hydrogen Peroxide?
 
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Old 03-12-20, 08:07 PM
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Buy it by the case and put it in a garden sprayer.
 
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Old 03-13-20, 04:56 AM
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"...a device installed that is supposed to render a dehumidifier useless while also purifying the air." Boy does that sound suspicious. For a room sized area a dehumidifier is really your only choice unless you want to heat the basement. Peltier (no compressor) dehumidifiers are ok for small, enclosed spaces but for a basement where you have a much larger area and potentially much more moisture to remove a compressor style dehumidifier is the better choice.
 
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Old 03-13-20, 05:08 AM
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Winter time usually creates a problem with air being too dry, not high humidity. If we review your system maybe we can identify the source of the moisture?

Does this control system have a water connection where it can also add moisture?

Do you heat the house and water with N Gas or propane?

Bud
 
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Old 03-13-20, 12:43 PM
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No, the control system does not add any water. It is esentially supposed to be an air purifier that removes moisture also. The house is heated with natural gas. The mold was there but barley noticable in the summer when moisture was much higher. It was suggested to me that the mold could have increased because of the air flow of the heating system in the winter in spite of the lower moisture.
 
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Old 03-13-20, 01:35 PM
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"It was suggested to me that the mold could have increased because of the air flow of the heating system in the winter in spite of the lower moisture."
No foundation for that statement we will ignore it.
Is this a new-ish house that might be considered tight?
House heated with natural gas and probably hot water as well means we need to examine the possibility of backdrafting those exhaust. if they are new direct vent appliances then not a problem. But if naturally drafted under certain conditions they may be backdrafting into the basement and that exhaust delivers a LOT of moisture. And you would not necessarily smell it as it is the same byproduct that a gas range gives off. I assume you also cook with gas?

Tell us more about your gas appliances and cooking habits. When cooking do you always run the exhaust fan?

Low probability but a possible contributor that needs to be checked off. What raises my concern is the extra moisture in the winter, it has to be coming from somewhere.

Bud
 
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Old 03-18-20, 09:07 PM
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Definetly not a new house and not remotely "tight". Newer water heater is a power vent. Have had lots of freezing and thawing the last few months. We got roughly 5 inches of snow on two or three occastions which melted almost immediantly. Has also been raining a little. No active leaking per say in the basement though. We do cook with gas but there is no exhaust fan.
 
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Old 03-19-20, 01:59 AM
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More questions?
Type of heat and how is that exhausted, power vent also or natural draft?
A couple of inexpensive humidistats that measure both temperature and humidity will let you take readings in different areas as well as outside. In winter colder outside air pushes in through lower leak areas which forces warmer house air up and out higher leak areas, taking some of the house generated moisture with it.

House generated moisture can come from several sources and those readings can help pin it down.

Note, relative humidity readings must include the temperature at the same location and time.

While we wait for the meter readings, here are some common moisture sources.
Showers without running a bathroom exhaust fan.
Drying clothe indoors or exhausting a dryer inside. Sometimes a disconnected exhaust duct.
Lots of house plants.
Cooking without a kitchen exhaust fan (already answered).
Moisture vapor passing through basement walls and floor.
Is the basement finished and what is on the walls?

Give us a nearby big city so we will know your climate region.

Bud
 
 

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