Treads stored on a job site should be covered and well of the ground.
Stair Tread Storage
1. Build platform of cull panel and scrap lumber 4x4s for stacking panels.
Stretch plastic film over platform to block passage of ground moisture.
2. Nail film to top panel and drape over ends for protection against driving rain.
Weight lower end with 2×4.
3. Lay two 2x4s on top of stack.
Pad corners with rags.
Stretch film over stack and secure to tie-down stakes.