How do you stop condensation in a container?
Stop condensation by moving air and removing moisture: fit louvered vents at both ends so the box breathes, add a solar exhaust fan if it holds anything that matters, keep desiccant inside and replace it, and never load damp goods. In Pine Belt humidity a sealed steel container will sweat on the ceiling every clear night without those steps, no matter what grade you bought.
Why steel sweats here
Summer dew points around Hattiesburg sit in the 70s for months. On a clear night the steel roof radiates heat and cools below that dew point, and the moist air trapped inside gives up its water onto the coldest surface — the ceiling. By morning it is dripping onto whatever is underneath, and by October anything cardboard is soft and anything fabric smells.
It is not a leak and it is not a defect of the grade. A one-trip box sweats exactly like a used one, because the problem is the air you sealed inside, not the steel. The fix is to stop sealing it.
What actually stops it
Vents. A pair of louvered vents, one at each end high on the wall, lets the box exchange air so the inside tracks the outside instead of holding a day's worth of moisture. Shipping containers come with tiny factory vents that are not enough. Bolt-in louvered vents are the first accessory to buy — on the accessories page with the rest.
A fan. A solar-powered exhaust fan in a wall vent pulls air through all day with no wiring. For furniture, paper, fabric, a workshop with tools that will rust, this is the difference between dry and musty.
Desiccant. Calcium chloride buckets absorb what the vents miss. They fill up; the one everybody forgets is the one that overflowed in June.
Nothing on the floor and nothing damp. Pallets or shelving under everything, so a drip or a damp floor never touches a box. Do not load the day after it rained on the goods. Shelving brackets that hang on the corrugation are on the accessories page.
Insulation, shade, and when a container is the wrong box
Shade helps — a box under trees or on the north side of a building swings less. Insulation (spray foam, or panels on battens) stops the ceiling getting cold enough to sweat and is the answer if you are making a workshop or office; a one-trip box with a clean interior is the right starting point for that, see one-trip vs used.
Some things should never be in an unconditioned container in this climate: photographs, instruments, electronics, leather, important paper. Those belong in a climate-controlled room. For everything else — tools, equipment, feed, furniture, inventory in plastic — a vented, blocked-up container stays dry year after year. 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
- How do you secure a container on a jobsite? — Securing a shipping container on a jobsite: why a lock box and puck lock beat any padlock, where to point the doors, and when a container is the wrong answer.
- Renting vs buying a storage container in Hattiesburg — Storage container rental vs buying in Hattiesburg, MS: when a month-to-month rental is right, when owning a used container wins, and what a Hub City lot needs.
- What are the interior dimensions of a 20ft container? — 20ft container dimensions: exact interior length, width and height, the door opening that limits what fits, the high cube difference, and what it holds.
- 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.
- Are containers good for farm storage? — Shipping container for farm storage: what a container is genuinely good at on a working place, where a pole barn beats it, and how to site one that lasts.
Across the Pine Belt
Hattiesburg · Petal · Laurel · Ellisville · Purvis · Sumrall · Columbia · Collins · Seminary · Wiggins