Black spots on roofing plywood inside brand new Amish shed

Just took delivery of a brand new Amish shed. The plywood sheathing has several areas of black stains and spots. We called the company who said, and I quote, oh yes, several of the customers buildings received with this batch had these spots, they called the owner of the manufacturer who assured them it was not mold but some type of ‘transference’ from something it was stored with. Said all the customers were fine with it. But, I’m not reassured. Is this mold?

 

It looks like mold/mildew to me. If it is, it will wash off with a bleach/water solution. That said, it really isn't anything to worry about. Mold requires 3 things to grow; moisture, heat and a food source. Take away any one of the 3 and it won't grow.

 

Thanks so much. That’s what we thought. I’m struggling with paying a lot of money for a brand new building with mold in it. We have another building from the same company with no issues, and other buildings on the lot do not have this, I guess just the most recent orders arrived this way. Is it normal to see this in new construction?

 

Unless a building is built inside a warehouse and all the materials are stored there [never getting rained on] it happens. On home construction most never see it because it gets covered up.

 

If you want to limit the mold you can add additional ventilation. In your photos I saw one, small vent near the peak. Are there any vents down low for air to enter? This is a case where more is better. But, it's still unconditioned so unless you move to the desert, get used to seeing mold.

 

There are two vents, one on each end (front and back) and then small windows on the back of the building. I have an older Amish built shed that we got 10 years ago from another company that they forgot to put the vents on, so we keep the windows cracked open year round. I haven’t seen mold (but I haven’t looked to be honest so it must not be obvious ) and then the shed we got before this a couple of months ago from the same company had no mold upon arrival, two vents, and two windows.

From what I’m gathering, I’m freaking out over something that is not uncommon and should just spray it, clean it, expect it might happen again, and let it go.

 

Shed, garage, or house, it needs to have proper ventilation regardless of size. I would agree that doesn't look sufficient.