Mold, moisture and clean pallets
Mold grows on wet wood. Wood below 20% moisture content will not support mold, mildew, decay or fungus, so the whole job is keeping pallets dry. Food and pharma docks should check for smell, stains and fuzz before a load goes out.
Why pallets go moldy
Pallets absorb water from rain, from condensation and from the trailers they ride in. Heat treatment does not protect against this: pallets loaded into a trailer while still hot are susceptible to mold, because the trailer traps the moisture the wood gives off as it cools.
Air movement helps. Even a slight air velocity of a few feet per second can keep stored pallets from molding.
What to look for
| Sign | What it means |
|---|---|
| Musty or sour smell | Mold or mildew, often before it is visible |
| White or green fuzz | Active growth |
| Black spots or dark staining | Older growth or water damage |
| Damp to the touch | Moisture high enough to support growth |
| Soft wood | Decay |
For food and pharma docks
A dock that ships food or medical goods should specify dry, clean pallets with no odor, and should reject anything with visible growth. We read for the same signs when we grade: mold is a reason to drop a pallet a grade or take it out of a sale. See food and beverage and biotech and pharma.
What to do about a moldy pile
- Separate it from the dry ones at once; mold spreads by contact.
- Spread the pallets out in the air to dry if the wood is sound.
- Tell us how long they sat wet. A few days is different from a season.
A pile that has molded through is a clear-out, and we will say so. See storing pallets to avoid it next time.
Drying a damp pile
Lay the pallets out in a single layer with air moving between them, out of the rain. Turn them after a day. Wood below 20 percent moisture content will not support mold, so drying until the wood feels dry through and smells like wood is the target. Mold that has grown into the grain does not come out, and those pallets are done.
A short inspection routine
- SmellLean over the stack. Mold smells musty before you see it.
- LookCheck the undersides of the deckboards, where moisture lingers.
- TouchPress a thumbnail into a board. Soft wood is decayed.
- RecordNote which pallets failed and why, so the source can be fixed.
Kiln-dried against green lumber
New pallets built from green lumber carry a lot of water, and the mold risk is highest in the first weeks. Kiln-dried boards start dry and stay dry if kept under cover. When you receive a new pallet that feels heavy or cool to the touch, set it out to air before you wrap a load on it.
Mold and customer complaints
A moldy pallet is the sort of thing a customer remembers. Receiving staff open a trailer, smell the stack and send the load back. The cost is the freight, the credit and the relationship. A two-minute inspection on your own dock is cheaper than any of those.
Prevention in storage
Keep stacks off bare ground, under cover and away from walls where air cannot move. A gap between stacks and a dry floor do more than any treatment applied later.
Telling stains from growth
Dark water stains are flat and smooth, while growth looks fuzzy, powdery or speckled and often smells musty. Rub a corner with a dry glove: stains stay put, growth smears.
Questions
- What moisture level stops mold on pallets?
- Wood below 20% moisture content will not support mold, mildew, decay or fungus.
- Does heat treatment prevent mold?
- No. A heat-treated pallet loaded hot into a trailer can grow mold.
Related
Sources
Last reviewed 2026-11-11.