Multiple failures

In December I noticed there was a small amount of snow dusting a table in the back end of the shipping container (aka Boomershoot Mecca) we use for Boomershoot target manufacturing. It had come in through a vent in the ceiling.

The vent is to keep it from getting too hot in the summer time. If the ammonium nitrate gets too hot it will undergo a phase change and change from prills to dust. We require prills for easy detonation.

I figured plugging the vent for the winter shouldn’t be a problem. So I plugged it and didn’t give it a second thought.

I didn’t count on a leak in the roof at the opposite end of the shipping container.


Even if I had imagined the leak I wouldn’t have thought it through.

What happened was the shipping container got a fair amount of water on the floor near the door. The shipping container gets pretty warm (maybe a 15 F increase above ambient on a windless sunny day) inside. This drove a lot of moisture into the air. The air probably stayed in the 80% to 90% relative humidity because there was no venting with the cool dry air from the outside. When the sun went down the interior temperature dropped and the air became supersaturated with water. It condensed on essentially everything. Not good.

I had thought things through enough when placing the container that I had about four inches of drop between the back end and the door. This meant the water drained toward the door rather than back to the cardboard target boxes and the chemicals. It destroyed one cardboard box that had stuff that was essentially immune to moisture like tie-wraps, wires, and bungee cords. But because of the lack of venting the water was migrating to all interior surfaces as the temperature cycled. All because I had not thought through the consequences of not having a vent in the winter simultaneous with a roof leak.

I think I caught it soon enough that it didn’t do any serious damage. One mixer was acting strange but I think I can fix it.

I fixed the roof leak and removed the plug from the vent. Then I put a tarp over the “drop zone” for the snow that might blow in through the vent.


I’ll inspect again when Barb L. and I go back for a visit later this month.


4 thoughts on “Multiple failures

  1. You need a work party in the summer: pull everything out, dry it out completely, gun on some foam and paint, then install just enough goldenrod-type heaing to keep the temp above ambient by a few degrees. Maybe even cobble up some power-venting with on-board computerized activation.

    For inspiration, visit some lower-end boat owners to see how they handle the same problem. The high-end guys have it built-in from the factory. Nicro makes the solar-powered vents.

  2. Joe,

    Shoot me an e mail, and I’ll reply to you with recommendations for what you need to do to fix that roof for the long term.

    I’m in the commercial and residential roofing business, and can point you to the right vendors and process to cure that roof for the long haul.

    Sunk New Dawn
    Galveston, TX

    • Cap’n Jim, isn’t the biggest problm in a ConEx box condensation? Keeping the snow/rain off the roof may be required (I’d think abput SnowRoof coating), but it’s all for naught if you don’t deal with the condensation issue.

      In Europe, people LIVE in Conexes, so there have to be answers out there.

      • Jim and I have been corresponding via email.

        The condensation problem went away as soon as I stopped the leak and opened the vent. Even the puddle of water on the floor was gone within a few hours. The air is very dry and the heated, by the sun, container evaporated the water surprisingly quickly.

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