Damp basement with mold

I have the same issue. I just recently discovered that my basement has a layer of mold/mildew on all contents and ceiling joists as well. My dehumidifier stopped working so I set a new one in and it was reading at 70%. Last week I installed 2 other dehumidifiers but I can't get it below 50% even with 3 running 24/7. I had a few mold cleanup people come in last week but I'm wondering if I can fog myself or what the best course of action is. Who should I call to figure out the source of the moisture since 3 dehumidifiers aren't keeping up. They are all 50pt. size so I find it hard to believe they aren't enough. All my downspouts lead away from the house and my house is only 10 years old.

 

99% of the time this issue needs to be addressed outside not inside.
Grade running away from the house?
No mulch piled up against the foundation.
No flower beds forming ponds around the foundation.
Any place where lines where ran through the foundation need to be sealed up from the outside.
Is there a sump pump and drain tiles under the floor?

 

If the humidity has been high for awhile it may take some time for the foundation and contents to dry out. That said, 3 dehumidifiers would be expected to be doing a bit better.

As foe what you can do, part of my energy business has been to measure air leakage and whatever leaks out must be replaced by outside air. Your location, state or nearby big city will tell us what outside conditions you are facing.

One difficult part to understand is that new homes are designed to leak. The target is a complete air change every 3 hours. If they build it tighter then they have to install an exchange system like an HRV (heat recovery ventilator).

First step in managing inside humidity is to pick up a combination temperature and humidity meter. You need those temp readings to adjust the humidity reading to a reference so the numbers can be compared. Instruction on how-to when ready.
Here is a calculator to do those adjustments.

Bud