Mold in shed

I recently built a floor with brand new 3/4in pressure treated plywood from home depot for a plastic modular shed....within a week the shed was covered in mold inside. It started on the floor but is now getting all over my lawn equipment and gas cans. At first I thought the shed did not have enough ventilation, but now I am wondering otherwise.

The pieces of plywood that were scrap from making the floor I left in my barn. The other day I was going through my wood pile and I noticed those brand new pieces of wood are absolutely covered in mold, no other wood in the barn has mold.

Is it possible I got tainted wood from home depot???? I never had a mold problem previously.

What do I do!?!

Darrin Darrin
Aug '17

Given the wood pile, Sounds like green untreated wet wood. Mold have much harder time on pressure treated. Take pictures, go to HD. Ask for them to cover equipment cleaner too.

If shed correctly on 4-8 inch of gravel, no way. I gather roof of vented too. So no way again.

If regular untreated ply, good luck. Still their fault but hard to prove.

Strangerdanger Strangerdanger
Aug '17

That is odd. I'm guessing the lumber was so saturated when you bought it now that they are in a less ventilated space, it is staying very wet. That coupled with the humid days we are experiencing is causing the mold growth. That really stinks as it is creeping to all of the other surfaces in the shed.
I would spray it down with a bleach/ water blend and perhaps incorporate some better venting or even a small fan on for a few days.


Get some TSP ( tri sodium phosphate and spray the wood...see what effect it has.

I use that when power washing before painting to remove mold .

Good luck !

Steven Steven
Aug '17

TSP cleans everything- I've used that in rental properties to remove smoke damage

Skippy Skippy
Aug '17

Even though it is pressure treated it still has glue between the layers that can delaminate. HD seems to be notorious for bad batches too. I would buy elsewhere.


The mold isn't really eating into the wood, but instead is surface mold....continual....and keeps coming back...of all types too its crazy...black, white, blue...everything

The problem is, with the fighting HD idea....there is absolutely no way they are going to take blame for that and replace my $160 of wood.

And to that affect, yes the wood was very wet when I picked it up, but lowes had no 3/4 stock on the day I needed it. I never though it would have, or have seen this happen. The wood looked wonderful when I picked it up, just absolutely saturated, which I thought nothing of.

Darrin Darrin
Aug '17

I would take pics, especially of the barn wood vs the " unmolded" next to them. I bet HD at least provides new wood. Again, thats if pressure treated. If not, wouldn't bother.

Hope you used screws.....

Course they might ask why a man with a barn needs a shed ;)

If you need to pressure treat, there is a way but not cheap and really toxic fumes. Have used with success on some pretty punky wood.

Strangerdanger Strangerdanger
Aug '17

SD, It was pressure treated, I think.....it had that green hue to it, and smells of treated lumber

Secondly, yes, I did use screws actually, the ones for pressure treated wood

2 problems though, I gotta find my receipt, don't know if I even still have it, and it probably too late....everything in my shed is cover with all kinds of mold, even if I was to put new wood down, the existing mold is just going to spread.

I bought mold killer spray and a dehumidifier...my thought was to plug the vents and maybe I can suck the shed so dry the mold will stop growing?

Darrin Darrin
Aug '17

Or service master, rt10 I think. Guy charged me $100 for two 2x3 ft drywall areas. Perfect and true pro. Thanks HL for rec.

Strangerdanger Strangerdanger
Aug '17

Wash it all down and scrub with TSP, the stuff works ...

Steven Steven
Aug '17

Also I would change the 3/4 pressure treated plywood to 3/4 cdx plywood.

Apro86 Apro86
Aug '17

CDX wouldn't be good for flooring.

It's meant for occasional moisture exposure, roof sheathing (under shingles), walls (under siding), etc. where it can withstand temporary rain, etc. until the outside layer is applied during construction.

Shed floors will have constant moisture exposure from underneath. Pressure treated is the right stuff.

Mark Mc. Mark Mc.
Aug '17

Back to the Top | View all Forum Topics
This topic has not been commented on in 3 years.
Commenting is no longer available.