ShippingCowHow to switch 3PLs for heavy products without losing orders
Count every unit and every carton spec first, because heavy SKUs cannot be re-created overnight. Send the new 3PL your SKU list, weights, dims and packing rules, then move inventory in one cutover week with a short parallel run. Freeze new inbound, keep the old 3PL live until the last order ships.
Why heavy SKUs make a 3PL switch harder
A 3 lb item can be replaced with a new one in a day. A 120 lb box cannot. You cannot air-freight a replacement, you cannot hand-carry it, and a mislabeled carton can cost a carrier claim and a customer.
Three things break most heavy-goods migrations:
**Carton data is wrong or missing.** The new 3PL rates and packs from your dims and weights. Guessed numbers become reweigh fees and surprise surcharges.
**Inventory is not counted.** Heavy units hide in corners, on top racks, and in returns. If your count is off, you oversell.
**Both warehouses ship at once.** Two systems, two tracking feeds, one customer. Orders get duplicated or dropped.
Plan the move around those three, and the rest is scheduling.
Step 1: Count inventory before you talk to anyone
Do a physical count at the current 3PL, by SKU, including returns and damaged units.
Count sellable, damaged, and on-hold separately. Damaged heavy units are a real number, not a rounding error.
Reconcile against your system of record. Write down every gap and its cause.
Photograph pallet and rack positions. This is your evidence if units go missing in transit.
Decide now what does not move: scrap, repair, or liquidate. Do not pay to transfer dead stock.
If your current 3PL runs the count, ask for a signed count sheet with date and counter name. Verbal counts are not counts.
Step 2: Build the SKU and carton data file
This file is the whole migration. The new 3PL builds its rate card, slotting, and packing rules from it.
| Field | Why it matters for 50–149 lb boxes |
|---|---|
| SKU and description | Ties the unit to the right pick face |
| Unit weight | Drives carrier rate and handling rules |
| Carton length × width × height | Drives DIM weight and oversize rules |
| Packing method | One box, two boxes, or box plus pallet |
| Units per carton | Prevents a 149 lb box becoming a 190 lb box |
| Label placement | Heavy cartons need labels that survive dragging |
| Hazmat or battery | Determines what the carrier will accept |
| Returns condition rules | Sets what gets restocked vs scrapped |
Send it as a spreadsheet, one row per SKU, with a version date. When a spec changes, send a new version. Do not send specs in email body text.
If you are still deciding between a 3PL and holding the warehouse yourself, read 3PL vs in-house warehouse before you sign anything.
Step 3: Get the new 3PL's answers in writing
Ask these before you commit to a cutover date. Get answers in the contract, not in a call.
1. What is your maximum carton weight and size per unit? What happens above it?
2. How do you handle a 100 lb box that needs two people?
3. Which carriers do you use for this weight band, and what is your mix?
4. What is your receiving process and appointment lead time for inbound freight?
5. How do you process a damage claim, and who files it?
6. How do you handle returns of heavy units, including inspection and restock?
7. How do you plan capacity for peak season?
For a longer list, use 15 questions to ask a 3PL as your call sheet.
Step 4: Set the cutover week
Pick one week. Everything moves inside it.
**Freeze inbound** to the old 3PL well before the move. New freight arriving mid-move is how units get lost.
**Stop new purchase orders** that would land during the move, or route them to the new 3PL.
**Book the truck** for the full inventory, with a pickup and delivery appointment on both ends.
**Ship in waves by SKU velocity.** Fast movers first, so the new site is productive on day one. Slow movers last.
**Send the data file again** the day before pickup, with the final count.
**Ask for a signed receipt** at the new 3PL, by SKU, with counts and condition.
Do not split a single SKU across two buildings during the move. One SKU, one location, until the count is confirmed.
Step 5: Run parallel for a short period
Parallel does not mean both warehouses ship everything. It means the old 3PL stays live as a fallback while the new one takes the volume.
Route all new orders to the new 3PL from cutover day.
Keep the old 3PL account open and funded until the last unit is confirmed received.
Watch three numbers daily: orders shipped, tracking uploaded, and exceptions.
Compare the first 20 heavy orders against your old cost per order to see how the new setup performs.
Close the old account only after the final inventory reconciliation is signed.
If your heavy orders are underperforming on the last mile, the carrier mix is often a factor. See ways to cut heavy shipping costs.
What to ask the new 3PL after week one
The first week tells you more than the sales call did.
What was the actual average cost per heavy order, all-in?
Which orders triggered accessorials, and why?
How many units arrived damaged or short?
What is the receiving-to-shelf time for the next inbound?
What would you change about our carton specs?
Ask for this as a written recap with dates. If the numbers do not match the quote, you want it in writing before month two.
Questions
How long does a 3PL switch take for heavy products? +
A typical switch runs several weeks: count and build data, get answers and sign, a cutover week, then a parallel run. Heavy SKUs take longer than small parcels because inventory cannot be replaced quickly.
Can I run two 3PLs at the same time permanently? +
Yes, and many heavy-goods brands do, splitting by coast to cut transit days. But run one 3PL per SKU. Two warehouses holding the same SKU is how you oversell and double-ship.
What happens to my inventory during the transfer? +
It moves on a truck under a bill of lading, with a count sheet at pickup and a signed receipt at delivery. Photograph pallets before they leave.
Do I need to tell my customers? +
Not usually, but watch tracking uploads for the first week. If tracking lags, a short note to affected customers beats a where-is-my-order email.
What if the new 3PL cannot handle my heaviest SKU? +
Find that out in step 3, before the move. Ask for their maximum carton weight and size in writing, and test one live order before you commit the full inventory.
Should I move everything at once or in waves? +
Waves, by SKU velocity. Fast movers first so the new site produces revenue on day one. Keep slow movers at the old site until the count is clean.
Get the next one by email
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The first step