Getting a Container Through a Mackay Wet Season

A container will shrug off a wet season most sheds won't survive. That's only true if it's set up before the rain arrives, not during it.

A container will come through a Mackay wet in a way very little else on the property will — provided somebody did the set-up work back in September. Units that get their first attention on the morning a low starts crossing the coast are the ones that cost their owners money.

Height is decided once, and it decides everything else

Before vents, before anchors, before any of the rest, work out where water goes on your place. Most people here have a fair idea: which paddock backs up first, where the drains around Goosepond and Vines Creek stop coping, how Marian and Mirani behave when the Pioneer is up, which northern beaches streets go under. Site the container above that line. The corner that suits the driveway is rarely the corner that suits a serious February.

Be clear-eyed about what the steel is doing for you. A cargo-worthy container is inspected wind and watertight, and what that describes is weather arriving from above: rain off the roof, spray off the walls, a storm coming in sideways. It says nothing about water rising from underneath. The doors are two leaves closing onto rubber gaskets at ground level, and water standing outside will find them — after which it has nowhere to go, because the seals that kept rain out now stop it draining.

The other half is buoyancy: an empty twenty-footer is a large sealed volume of air, and in deep enough water it lifts and goes where the current sends it. No container is flood-proof, and height on the block is the only part of this you genuinely control.

Off the ground, without exception

Concrete blocks, hardwood sleepers or heavy pavers under the four corner castings. Half an hour of work, two benefits: the floor sits clear of sheet water in a heavy fall, and air moves underneath so the cross-members dry between downpours. A unit left hard on wet grass through five wets corrodes from below where nobody looks, and the first anyone knows of it is a floor that gives under a boot.

Wind, and what to do with a light container

An empty 20ft comes in around two and a bit tonnes, with a very large flat side pointed at the weather. Plenty in ordinary conditions, nowhere near enough in a genuine blow. Lightly loaded units have been pushed off their blocks and turned over by cyclonic wind, and Debbie made that point across the Whitsundays and Proserpine in 2017.

If it is staying put for the season, anchor it properly: screw piles or engineered ground anchors fixed to the corner castings and rated for the load, not a strap over the top and a couple of star pickets. If a system is coming and the unit is close to empty, mass is the fastest fix — put dense weight on the floor and leave it there. None of that makes a container cyclone-proof, because nothing sold as a shipping container is. It makes it far more likely to still be where you left it.

The rain that starts on the inside

Here is the failure that catches people out. The roof is sound, the unit has never leaked, and everything inside comes out spotted with mould anyway.

Steel has effectively no insulation value. Through the day the roof takes on heat and the air sealed inside picks up moisture from the ground, the slab and whatever is stored. Overnight the roof sheds that heat and drops below the dew point of the air beneath it, water forms across the underside of the ceiling, and in time it falls. Through the build-up and into February that cycle repeats night after night.

Three things deal with it, and they work together rather than separately. Ventilation matters most, and it has to be at both ends — a single vent lets air sit, a pair lets it move through. Desiccant is next, and it needs to be the hanging tub sort rather than a few sachets, checked monthly. Third, break the contact between your gear and the floor with plastic sheet or pallets, since the ground beneath a container gives off moisture around the clock.

Twenty minutes, some time in October

Do this before the season, not in the middle of it. Get the leaf litter off the roof and look for any dented panel holding water instead of shedding it. Anywhere the paint has been knocked off and the steel has gone brown wants a wire brush and a coat of cold-galv, because a wet season will take a paint chip a long way in three months. Put grease through the locking bars, cams and hinges. Replace any door rubber that has gone hard.

Then get inside, pull the doors closed behind you and give your eyes a minute to adjust. Pinholes show themselves as points of daylight and there is no other easy way to find them.

Grade matters too. Cargo-worthy units are inspected wind and watertight before they leave; as-is units are cheaper and are not sold watertight, which makes them a lock-up rather than wet season storage. Ask and we will send photos of the actual container before delivery.

Not sure whether your spot is a good one, or what condition an older unit is really in? Ring (07) 4944 2211, or read what we need to get a container onto your block.