Mold on my lumber

[Dan Hahr]

I just went out to my shed and was disappointed to see some patches of mold on the face of a wide oak board that I have been storing for over 8 years. I recently built a 16x12 wooden shed to house my stash of lumber. Previously, it was stacked the same way in my garage. I moved it out to the shed a couple of months ago. Over the last couple of weeks we have gotten a lot of rain. I haven't finished my shed doors yet, and there is a small crack around the perimeter of them. I have 8 soffit vents and a full ridge vent, which should be plenty of ventilation.

I originally thought that some water blew in and the damp conditions kept those spots from drying out. Then I went to get my good flashlight and realized that almost all of the top surfaces of the lumber had a thin greyish cast that wipes off with a finger swipe. The walls are not affected, and neither are the floors. When I moved the boards around, lines of exposed wood were defined by greyish mold.

Has anyone ever experienced this before? I am sure the humidity has been quite high and I know it will fluctuate over the course of the year. However, this has never happened in my garage and it is not heated or cooled, and it stays open most every day. I plan on putting a small heater in the shed until we get some warm weather, but I don't want to have to keep it conditioned all the time, and I don't have electricity run to it. I can leave the windows open, but I'm not sure if that would make it worse or not.

Any suggestions?

Thanks, Dan

[Peter Quinn]

Dan...I don't know how to tell you this...but you I've in a swamp. Yes, nearly the entire state of FLA is by CT standards, officially a swamp. My parents live there, when I go to visit I'm pretty sure I could grow mold if I stood still long enough. I had mold grow on some lumber in my old dank garage that was backed into a hill on two sides, was during a particularly wet and humid summer here in CT, red oak IIR, and some poplar which molds pretty readily. Built a new garage since with proper drainage, water proofing and moisture barrier, end of problem. Suggestions? Keep your lumber in conditioned space. Big dehumidifier.

[Jim Andrew]

Any chance there is a leak in the roof? Otherwise, use a room dehumidifier.

[Jay Radke]

a room dehumidifier in an outside shed in FLA? make sure you have a hose connected to that thing as you would have to empty the bucket every 30 mins. god only knows how much power that will use.

[Keith Hankins]

I see two options. Get that wood in the house where there's air conditioning. Move the wife to the shed if you have to free up some room. Or, you can treat with a mild solution of bleach n water to kill it.

[Dan Hahr]

I guess I'll spray it down with bleach and run some fans to dry it out. I was just surprised to see it show up o. Kiln dried wood.

Thsnks for for the replies, Dan

[Prashun Patel]

You're sure it's mold, right? Oak turns black or grey for a couple reasons.

I'd expect to see more mold on the sandwiched pieces more than on the exposed parts.

Can you post a pic?

[Allan Speers]

If it really is mold, get yourself a few gallons of Sporicidin and a decent had sprayer. Bleach doesn't usually kill mold except on the surface, it will come back. Sporicidin is the STUFF, believe me, and it's not horribly expensive.

Also, it's environmentally friendly, (you can drink it) whereas bleach is just downright nasty stuff.


- Oh, and if your lumber is going to continue to be in such damp conditions, I'd be very worried about powder post beetles. Better spray some boric acid solution over the stacks. I recently discovered that a few thousand BF of my QS White Oak (Stored outside under tarps) is beetle-infested, and I wanna' just shoot myself.

[Robert Engel]

I guess I'll spray it down with bleach and run some fans to dry it out. I was just surprised to see it show up o. Kiln dried wood.

Thsnks for for the replies, DanI live in NE FL. I think what you're seeing is most like mildew, not mold.

To the yankee (:)) in CT not all of FL is a swamp, only about 73% of it. The rest is "swamp like", OK? ha ha
Humidity is a problem. I'll bet somebody in Seattle has similar problems.

Dan, I think you're problem is the shed is closed up and you've basically got a greenhouse going on there. I would definitely check for leaks.
I have a small farm and I store some wood with nothing but a sheet on tin on top no mildew, mold or rot.
I also store some lumber in open stall next to my shop in a barn (converted pole barn) and I've never had this problem. I have had mildew grown on MDF, though, right inside my shop that was kinda weird.

So I think it has to do with ventilation mostly.

I think you need to get the wood out of the shed. Wiping it down with bleach/water solution is ok but in the end, I don't think it matters that much it will mildew again. For some kinds of wood it will permanently stain it.