Planning for Self-Built Container Houses
Planning for self-built container houses requires systematic design from six aspects: site selection and foundation, structural modification, thermal performance, spatial organization, lighting and ventilation, and construction and maintenance. The specific key points are as follows:
I. Site Selection and Foundation Container houses have strict requirements for foundations and need to select foundation types based on geological conditions: Concrete strip foundations or independent column foundations are suitable for permanent land, with spacing aligned with the corner fittings of the container; for temporary land or hillsides, screw steel piles (diameter ≥ 89 mm) can be used, with the depth of insertion exceeding the frost line. The top surface of the foundation needs to be pre-embedded with 20 mm thick steel plate connectors, welded or bolted to the corner fittings of the container, with a 300 mm wide, 5% slope apron around it to prevent rainwater backflow. If the site is at risk of waterlogging, the foundation should be raised more than 300 mm above the ground, and maintenance space should be reserved at the bottom of the container.
II. Structural Modification When cutting doors and windows or打通 (connecting) adjacent containers, structural strength needs to be compensated: For a single opening ≤ 1.5 meters, reinforce with square steel tube frames; for openings > 1.5 meters or continuous openings, add crossbeams or columns. All door and window openings should have 80×80×3 mm square tubes welded along the top and bottom edges, firmly connected to the original structure; when connecting two containers, a steel beam should be welded above the opening, with both ends must resting on the original corner columns or newly added columns. Cutting operations should use plasma cutting machines, with the cuts polished smooth. The welds should be full welds with a weld height ≥ the thickness of the base material, and two coats of epoxy zinc-rich primer should be applied for rust prevention after completion.
III. Thermal Performance The original container walls have a high thermal conductivity coefficient and require a continuous insulation layer: It is recommended to have, from outside to inside, metal carved panels or anti-corrosion wood cladding (rain and sun protection), a 30 mm air layer (ventilation and exhaust), 50 mm extruded polystyrene board (XPS, fire rating B1), the original steel plate, 50 mm rock wool internal insulation (placed within the studs), and 9 mm OSB board or gypsum board. In northern regions, polyurethane spraying (≥ 80 mm) or extruded boards (≥ 50 mm) can be used, while in southern regions, rock wool (≥ 50 mm) with a moisture barrier is suitable.
IV. Spatial Organization Using a 40-foot high cube container as the basic unit, the public areas (living room, kitchen, dining room) are placed in the middle, and the private areas (bedrooms, bathroom) are placed at both ends to reduce noise interference. Module combinations can adopt a linear shape (2-3 containers side by side, with waterproofing and insulation at the connections), an L-shape or U-shape (enclosing a courtyard, with H-shaped steel reinforcement at the corners), or a stacked shape (upper and lower layers staggered, requiring load calculation, with a foundation bearing capacity ≥ 150 kPa). Vertical expansion can include setting up a loft or mezzanine (clear height ≥ 1.2 meters), built-in storage utilizing the wall cavity (100-150 mm) for custom cabinets, and multi-functional furniture such as fold-out beds and folding tables to improve space utilization.
V. Lighting and Ventilation Lighting optimization: Side windows should be long and narrow (width 1.2-1.5 meters, height 0.9-1.2 meters, lighting coefficient ≥ 1.5%), with skylights on the roof (0.6 meters × 0.9 meters, using EPDM waterproofing membrane), and Low-E insulated glass (5+12A+5) installed at the ends or connection interfaces. Ventilation system: Natural ventilation design with opposing windows (window-to-floor ratio ≥ 0.12), and mechanical assistance with silent exhaust fans (air volume ≥ 150 m³/h) or a heat recovery ventilation system (CO₂ concentration < 1000 ppm).
VI. Construction and Maintenance Approval procedures: Rural homesteads require construction approval, with structural drawings provided; cultivated land and basic farmland are strictly prohibited from construction, and forestry approval is required for forest land; leased land is mostly for temporary structures, and the contract must specify the nature of use. Rust prevention maintenance: During the construction phase, cuts need to be polished and painted, and welds, corners, etc., should be inspected annually. In inland dry areas, heavy-duty anti-corrosion coating is required every 8-12 years, in southern humid areas every 7-10 years, and in coastal areas every 3-5 years. Waterproof sealing: The sealant around doors and windows, container body joints, and roof gutters needs to be replaced every 5-7 years, and the roof should be cleared of leaves annually to prevent water accumulation.
