Container house fans want cheap, but may not get it.
Welcome back to SIP HAUS. We’ve had visits recently from some tiny house fans mentioning container houses, pointing out that the whole container can be had for under a few thousand dollars. That’s true. But there are two key reasons why houses aren’t all built like sea containers: occupant health and cost. Fitting out a container house might seem easy, but achieving a good result is difficult. Water leaks, flashing issues, internal finishing and cladding work, as well as coping with narrow spaces that inhibit socialising. Add to that the health risks of single skin dwellings as well as heat flow through the walls and roof that lead to massive heating and cooling bills and the gloss on steel is fading. Steel is energy intensive to make, energy wasted when used to displace a low energy substitute. Better we believe to respect the value of embodied energy in the sea container and allow it to recycle it into other steel products.
It’s tricky to make a liveable home from a sea container. Door or window holes cut into the steel might not always be sealed properly and may leak. Another drawback is that although steel has an aesthetic value most will want to cover a lot of the internals with insulation and plasterboard rather than suffer the heat or cold of a large metal surface. Linings don’t fix easily into steel so a secondary internal timber frame out may be needed taking time and money.
Clearly buildings should be healthy places to be, so they nearly always have a cavity between the cladding and the frame because ventilation keeps materials dry and well preserved and prevents unhealthy mould growth. If the steel shell lets in water that may spell the end of your healthy home, as mould, rust and rot set it, so an external cladding is often essential. For this reason, professional container home suppliers use new containers, not second hand. Even if new, a wall can‘t be removed without then adding strengthening members. So allow for the cost of an engineer to check the integrity of any modified structure.
By the time the container is clad, flashing difficulties addressed and internal finishes applied the dream of saving money has probably lost much of its shine, but if it still beckons, consider this: the insulations values are rarely sufficient to deliver a comfortable and energy efficient home. When sufficient insulation is included, the internal width narrows further. It’s already only 2.3m, then subtract 150mm from each wall and it’s a 2m wide space – marginal for humans to live in, a prison cell in effect. If the insulation is added to the outside, then an additional framework is added to carry the cladding and create an air cavity. Thick 150mm insulation will be needed because unfortunately the long skinny shape of the 40’ container gives a lot of steel surface area so heat flow is really maximised otherwise.
Modifying sea containers is an entertaining but short-term and temporary solution at best. There are easier, simpler and more long-lasting building solutions such as SIPs, or stud wall construction, producing buildings that require little energy to create and little energy to operate and that don’t come with the hidden costs of using a sea container. Real building systems produce healthy delightful spaces where humans can flourish and grow such as our Pop Cottage for example.