Station 3 of 6 Deliver and store
Bread Tray Storage: Maximizing Warehouse Space with Nesting and Stacking
Contents: 5 sections
The floor space empty trays need comes from two numbers most storage plans skip: how many trays fit in one column, and how many columns you need. A column’s count is set by the tray’s nest increment and your height limit; the columns times the tray’s footprint gives the floor area, before aisles. Nested stack-and-nest trays can need a fraction of the floor that the same trays need stacked, so measure the increment and run the numbers before you assign space.
How much floor space do empty trays need?
Work it out in four steps:
| Step | Formula | Example (illustration) |
|---|---|---|
| 1. Trays per column | 1 + ((height limit − tray height) ÷ nest increment, rounded down), or the maker's nesting limit if lower | 1 + ((54 − 4.95) ÷ 1.025) = 1 + 47 = 48, if the maker allows 48 |
| 2. Columns | Trays to store ÷ trays per column, rounded up | 1,000 ÷ 48 = 21 |
| 3. Floor area of the columns | Columns × tray footprint (outside length × width) | 21 × 4.16 sq ft = 87 sq ft |
| 4. Staging area | Floor area of the columns + the aisle and sorting space your equipment needs | Measured on your layout |
Sources for the table: tray height 4.95 inches, nest increment 1.025 inches and outside size 27.0 x 22.16 inches for the Rehrig Pacific 28 x 22 tray, from its product page; the 54-inch limit and the 1,000 trays are illustration values; the formulas are ours.
Step 1 uses the nest increment, the height each empty tray adds when nested, which is how makers who publish both figures let you compare trays in inches; the definition, and why “nest ratio” labels are not comparable between makers, is in measuring nest and stack increments in inches. If trays are stored on dollies, add the dolly’s height to the tray height in step 1 and use the dolly’s footprint in step 3 if it is larger than the tray’s.
Nesting is where the space goes. The same 1,000 trays stored in their stacking position, which adds 4.08 inches per tray on this model, fit 13 to a column under the same 54-inch limit: 77 columns and about 320 square feet, against 21 columns and about 87 square feet nested. A tray that only stacks has no nest increment, so its empty storage looks like the stacked figure.
What sets the height limit for a column?
The lowest of four limits:
- Hand reach. If people build and break down the columns by hand, this guide’s screening rule stops the column where your shortest stacker would have to lift above the shoulder; lifts below that still need a NIOSH check. The rule, and how to turn it into a tray count, is in setting the hand-stacking limit from shoulder height.
- The maker’s limit. Some makers limit how many empties may be nested in one column. Ask for it in writing for your model.
- Overhead clearance. Measure to the lowest obstruction in each zone: racks, ducts, lights, sprinklers. Under automatic sprinklers, OSHA’s sprinkler rule says: “The minimum vertical clearance between sprinklers and material below shall be 18 inches (45.7 cm)” (29 CFR 1910.159(c)(10)). Your local fire code or insurer may require more; ask them.
- Stability. A tall column of light, empty trays can be knocked over by passing equipment. If columns stand near forklift aisles, keep them lower or protect them.
Loaded trays do not nest. For loaded stacks, use the stack increment instead of the nest increment in step 1, and the lower of the same limits.
How should the storage area be laid out?
To make sorting and counting quick:
- One zone per tray model and depth. Mark each with floor tape or paint. Mixed models and depths do not nest or lock correctly together, so a mixed column is both unstable and hard to count.
- Clean and dirty trays apart. Returned trays waiting for the washer are stored separately from clean trays, with a physical boundary between them.
- Rotation. Clean trays enter a lane at one end and leave from the other, so the trays that came back first go out first without anyone having to track them. The point is to spread wear and keep stacks from sitting unseen for months, not food-style rotation; a tray does not expire.
- Fixed column heights. If every column in a zone holds the same number of trays, counting is columns times trays per column, and a short column stands out.
- Busiest trays nearest the point of use. Trays used every day go next to the loading line or dock; seasonal or specialty trays go furthest away, labeled with when they will be needed.
- Quarantine for damaged trays. A marked area, away from both clean and dirty storage, for trays waiting for inspection.
Size the area for the most trays you will hold at once, not the average. That is highest when the fleet is largest and trays are in the building: before a seasonal peak, when extra trays have arrived, and in quiet periods, when more of the fleet sits idle. Your fleet level from your inventory records gives the count.
Is the space problem storage, or returns?
Check before you rearrange. If trays pile up in storage while stores hold large balances and routes run short, the problem is the return timing, not the floor. If storage overflows even when store balances are normal, you are holding more trays than the loop needs, or holding them stacked instead of nested. Fix the one you actually have.
What should you measure first?
The nest increment of the trays you store, the lowest height limit in each storage zone, and the most trays you hold at once. With those three numbers, the table above gives your columns and floor area, and you can see whether nesting, a lower column height or a different layout makes the difference. For the counts that tell you how many trays should be in the building, see the loss and counting guide.