In the early summer, I arrived at the shed to start getting it in shape for the open house I had planned for my family around Labor Day.

When I entered the shed, I had an unhappy surprise.

Black mold was starting to grow on my shelves. Not the steel uprights, but the plywood shelving. The mold was worse on some shelves than others, and was mostly limited to the shelves lowest to the concrete floor. It wasn’t that there was a lot of mold…there wasn’t much. It’s just that I didn’t think there should be any mold at all.

I turned to my most reliable source of information, the internet, and here’s what I learned:

1. This is a common problem.
2. It is potentially dangerous, particularly if you breath the mold.
3. There are at least two good ways to get rid of the mold, bleach and Borax.
4. Bleach works better initially, but doesn’t penetrate the wood, so it leaves some mold alive deeply invaded into the wood fibers. Also, once it dries, the mold-killing properties evaporate (the chlorine dissipates into the air), so there is nothing left to prevent mold from returning.
5. Borax (20 Mule Team) works almost as well as bleach at getting rid of mold, but unlike bleach, it does penetrate into the underlying wood fibers. When it dries, it leaves behind a thin film of Borax that continues to inhibit mold growth for a pretty long time.

So I got to work with Borax, and left the shelves wet, hoping to provide some protection.

I also looked at preventive measures. Why did the mold form in the first place?

It formed (I learned from the internet) because of condensation issues within the shed. The shed is both insulated against the heat, and ventilated.

• The insulation means that during hot, humid summer days, the inside of the shed remains relatively cool, particularly the concrete floor.
• The good ventilation insures that there is a steady supply of warm humid air coming into the shed through the under-the-eaves vents. When this warm humid aid meets the cool concrete, condensation occurs, which promotes growth of mold.

My sources suggested turning on a fan, to stir up the air, making it a more even temperature inside the shed. The floor won’t be so cold, and any condensation will more easily dry (and dry quickly) because of the circulating air. OK. I turned on my ceiling fan.

I was still a little shy about using much electricity, based on my experience with the cost of the electric space heater, but it seemed like running a ceiling fan all the time probably wouldn’t use that much current.

I locked the door and went back home.

6 weeks later I returned.

1. The mold was gone, as far as I could tell, and none had returned.
2. The total cost for running the fan continuously for a month was a little over $4.00. I was willing to absorb that cost to prevent more mold from arriving. I’m not sure whether I need to run it over the winter or not…I’m still reflecting on this.