Does a shipping container need a moisture trap in south Mississippi?
Yes, but only as the backup: in south Mississippi a container moisture trap soaks up the damp that vents miss, and it cannot keep a closed steel box dry on its own. Vent the container first so humid air has a way out, then set a few calcium chloride traps inside and empty or replace them often through the summer.
What a container moisture trap does, and what it cannot do
A container moisture trap is a tub or hanging bag of calcium chloride that pulls water out of the air and collects it as liquid. Shippers hang them in loaded boxes crossing the ocean. If you are buying a used shipping container in Hattiesburg, Laurel or anywhere in the Pine Belt to keep behind the house or at the camp, the question is whether those traps are enough here.
They are not, on their own. A trap holds a fixed amount of water, and a south Mississippi summer puts a lot more than that into a closed box — every time the doors open, and every night the roof cools below the dew point and the ceiling sweats. A sealed container with traps and no vents fills the traps and then drips anyway. Container condensation explains why steel sweats here; a one-trip conex box sweats the same as a used one.
Vents first, then the trap
Moving air does the heavy work. A pair of louvered vents, one low and one high on opposite walls, lets the damp air leave on its own. The rectangular vents with bug screens come as a 2-pack, and the ventilation kit adds a powered exhaust fan for a box in full sun or one holding feed, tack or tools that rust. Which vents stop sweating covers how many you need and where they go.
Everything ships separately and you install it — nothing arrives on the box. The fan and lights bolt on, but each vent needs one opening cut in the wall. A worn door seal lets humid air in around the doors; on an older used box a new door gasket is worth checking for.
Then add the traps. We do not sell them; any hardware or farm store in the Pine Belt carries calcium chloride moisture absorbers. Put a few in a 20ft and more in a 40ft, spread down the length, up off the floor and away from anything that would be ruined by a spill — the liquid they collect is salty and eats at steel and wood.
Checking traps through a Pine Belt year
Look at them monthly from May through September, when they fill fastest, and replace any that are more than half liquid. In winter they slow down. The trap that overflows is always the one nobody checked in July.
Keep everything on pallets or shelving so a drip never touches a box. The Farm Feed Room and Hunting Camp Box packages put a container and its vents at one delivered price, with the kit shipped separately for you to install. For a shop with tools that rust, see insulating a container in Mississippi heat. Pick your box — the 20ft used WWT is the common storage buy — and the delivered price for your ZIP is on the containers page. See containers for sale — delivered price by ZIP
Buying a container?
Longleaf sells used and one-trip 20ft and 40ft shipping containers, delivered by tilt-bed across the Pine Belt. Enter your ZIP for the delivered price — it comes straight from the supplier feed and already includes the haul. Locks, vents, shelving and lights are on the accessories page. We sell; we do not rent.
- 20ft Standard Cargo Worthy (used) — from $2,885 delivered
- 20ft Standard One Trip (new) — from $3,635 delivered
- 20ft Standard Wind & Watertight (used) — from $2,470 delivered
- 40ft High Cube Cargo Worthy (used) — from $3,525 delivered
- 40ft High Cube One Trip (new) — from $4,925 delivered
- 40ft High Cube Wind & Watertight (used) — from $3,210 delivered
- 40ft Standard Cargo Worthy (used) — from $3,525 delivered
- 40ft Standard One Trip (new) — from $6,355 delivered
- 40ft Standard Wind & Watertight (used) — from $3,160 delivered
Keep reading
- Where can I buy a shipping container in Ellisville, MS? — Shipping containers for sale in Ellisville, MS: used and one-trip 20ft and 40ft boxes delivered to 39437 and south Jones County, plus the checks to make first.
- Where can I buy a shipping container near Seminary, MS? — Shipping containers for sale in Seminary, MS: used and one-trip 20ft and 40ft boxes delivered to 39479 and Covington County, and the flood check to make first.
- Should I buy a used or one-trip container in Mississippi? — Used vs one-trip container price in Mississippi: what the gap between a used WWT box and a near-new one buys you, and which one a Pine Belt buyer should pick.
- Which vents stop a shipping container from sweating in south Mississippi — Which vents stop a shipping container from sweating in south Mississippi: louvered pairs, solar fans, roof vents, where to cut them, and how many you need.
- Storing a boat on its trailer in a 40ft container on the Gulf Coast: width, height, vent and moisture — Storing a boat in a 40ft shipping container on the Gulf Coast: door width and height limits, trailer and T-top clearance, salt air, moisture and storms.
Across the Pine Belt
Hattiesburg · Petal · Laurel · Ellisville · Purvis · Sumrall · Columbia · Collins · Seminary · Wiggins