What the owner noticed
| When | Observation |
|---|---|
| After rain | Musty smell strongest near the rear doors |
| Dry weeks | Smell fades but never quite goes away |
| Floor | Plywood floor dark and soft near the door sill |
| Racks | Cardboard parts boxes on the bottom shelf swollen |
| Cab | Cab fine; smell stays in the cargo area |
Tracing the water
Illustrative example. Not a real job or customer.
Illustrative example, not a real vehicle, owner or business. A small Arvada plumbing company's cargo van smells musty in the back. The owner first suspects drain parts and used fittings riding in bins.
- The owner removes all used parts and bins. The smell remains.
- After a rainstorm, they pull back the floor mat by the rear doors and find damp plywood and a line of water along the sill.
- A shop inspects the rear door seals, which are cracked and flattened at the bottom corners after years of daily use.
- The seals are replaced. The rotten section of plywood is cut out and replaced, and the rest dried with fans for two days.
- Cardboard boxes move to plastic bins, and a rubber mat with raised edges goes down by the doors.
The smell disappeared once the water stopped. The owner added a seal check to the van's annual service list.
Why work vans leak
Cargo van rear doors open and close dozens of times a day. Seals compress, crack and pull away at the corners, and the plywood floors many upfitters install soak up water like a sponge. Racks and shelving bolted through the floor add more paths for water.
Because the cargo area is separate from the cab, a leak can go on for months before anyone notices more than a faint smell.
Checking a van for leaks
A simple hose test finds most cargo van leaks. Close the doors, have someone inside with a flashlight, and run water slowly along the top and sides of the rear doors, then the side door, then any roof racks or vents. Watch for drips along seals, around bolts and at the corners where seals usually fail first.
Upfitted vans with ladder racks, shelving and roof vents have more holes than a factory van. Each fastener through the body is a possible leak, and sealant around them ages. An annual check is cheap compared with replacing a rotten floor.
Common questions
Can a musty van floor be treated without replacing it?
If the plywood is still firm, drying it fully and fixing the leak may be enough. Soft, delaminated plywood should be replaced.
Do work vans need a vapor barrier under the floor?
Many upfitters add a sealed or rubber-coated floor that resists water better than bare plywood.
General information for Arvada, not a quote or professional advice. In an emergency, call 911.