What each term actually describes
Buyers often use "modular", "prefab" and "container" interchangeably, but in procurement documents they describe three different things: a construction method, a family of building systems, and a shipping-derived structural format. Understanding the distinction matters because it determines what you can specify, how the structure is transported, and whether it can be relocated later. This article sets out the differences in engineering terms, with reference to the systems manufactured by Beijing Chengdong International Modular Housing Corporation (brand CDPH), so that project teams can select the right format before tendering. Modular homes sit at one end of this spectrum: they are built as volumetric units in a factory, complete with structure, envelope, services and finishes, and are then bolted together on site.
Modular houses: volumetric, engineered, relocatable
A modular house is assembled from factory-prefabricated standard modules that are bolted together on site. Because each module is a complete three-dimensional unit — frame, floor, roof, walls, electrical circuits and plumbing — site work centres on foundation preparation, lifting, connection and service hook-up. The system is relocatable and reusable: modules can be unbolted, transported and re-erected elsewhere, which is why modular homes are widely used for engineering camps and other facilities with a defined project life.
CDPH modular houses are built on a galvanised cold-formed steel frame (SGH340, t=3.0 mm), prefabricated in the factory. Roof and floor insulation is 100 mm glass wool; walls use 75 mm colour-steel sandwich panels and seamless S-type rock wool composite panels. Flooring is 1.5 / 1.6 mm rubber-plastic, with steel doors and integrated PVC sliding windows with security bars and fly screens. Electrical circuits are pre-fitted in the roof, water supply runs along the walls, and drainage is wall-side — all of which reduces site trade coordination.
Two standard module sizes are produced:
- 6055 × 2990 × 2896 mm (internal 5845 × 2780 × 2500 mm)
- 6055 × 2435 × 2896 mm (internal 5845 × 2225 × 2520 mm)
Design loads for the standard module are a roof live load of 1.0 / 0.5 kN/m², floor live load of 2.0 kN/m² and wind load of 0.6 / 0.5 kN/m². Buildings can be single, double, triple or more storeys, in I, U, L or courtyard layouts — a configuration that matters for camp planning, where accommodation, offices, canteens and welfare blocks are usually combined on one footprint.
Because the module is the base unit, several transport and assembly variants are built on the same system. Flat pack modules are the 6055 mm standard box packed flat for transport and assembled on site; detachable modules are bolted, demountable units that can be taken apart and reused. If your project involves multiple sites or a phased relocation, this family of formats is worth discussing early with the manufacturer.
Prefab houses: the wider category, including open-plan and wide-span structures
"Prefab" is the broader term: any building substantially manufactured off site. It covers volumetric modular homes, but also panelised and steel-frame buildings that are assembled on site into a single continuous structure rather than a stack of boxes. These are not normally relocatable as modules, but they offer larger clear spans and simpler logistics.
CDPH produces two prefab house series. The ZA Series is a highly prefabricated design with fast installation and flexible layout, built on a hot-galvanised cold-formed steel structure with corrosion-resistant, well-insulated external wall panels. Interior fit-out options include bathrooms, kitchens, storage rooms, bedrooms, living rooms and open-plan offices. Spans reach up to 12 m, with eaves height up to 3.5 m for accommodation/office types or 4.5 m for storage types (customisable). Column spacing is 3.45 m, roof slope 1:5, roof live load 0.50 kN/m², wind load 0.45 kN/m², and the working temperature range is −25 °C to +50 °C. Columns are cold-formed steel T=2–3 mm, hot-galvanised; wall panels are 75 mm colour-steel sandwich panels (white) and the roof uses 75 mm corrugated colour-steel sandwich panels (blue). Doors are 900 × 2100 mm steel, customisable, with UPVC or aluminium alloy windows. For planning purposes: four workers erect about 40 m² of structure per day, and about 200 m² of structure ships in one 40 ft container.
The ZM Series is the wide-span variant, with spans of 12, 15 or 18 m, eaves height 6 m and column spacing of 4 m or 6 m. Roof slope is 1:5; roof live load is 0.3 kN/m² at 6 m column spacing or 0.50 kN/m² at 4 m spacing; wind load is 0.45 / 0.60 kN/m² and snow load 0.35 / 0.50 kN/m². Columns are M300 steel T=3.0 mm hot-galvanised, purlins C170 T=2.3 mm hot-galvanised. Openings include a 4000 × 4000 mm sliding door and a 1500 × 2000 mm double door, both customisable. Ten workers erect about 1,000 m² of structure in five days, and about 170 m² of structure ships in one 40 ft container. Typical uses are warehouses, workshops and storage buildings.
Container houses: a format, not a construction method
In the wider market, container houses are derived from ISO shipping container dimensions. They offer a familiar footprint, straightforward stacking and global transportability, and they suit temporary or semi-permanent accommodation, site offices and welfare facilities. The limitation is dimensional: the module is fixed by the container envelope, so large open-plan spaces and wide spans generally require multiple units, removal of internal walls within a structural frame, or a different system altogether. Where a project needs a 12 m clear span for a workshop, a prefab wide-span building is the correct choice rather than a container derivative.
CDPH's container houses are its modular platform supplied in container format — not a separate ISO-derived product family — so the comparison can be made on project requirements rather than on a single product line. Note that certification scopes differ by product family: CE certification covers modular container houses, prefab houses and light steel villas, and buyers should confirm the applicable scope for their destination market.
Side-by-side comparison
| Characteristic | Modular house | Prefab house (ZA / ZM) | Container house |
|---|---|---|---|
| Base unit | Volumetric module, 6055 mm standard box | Steel-frame building assembled on site | Container-format module (CDPH: the standard 6055 mm module; ISO-derived in the wider market) |
| Relocatable / reusable | Yes — bolted, demountable | Generally not as modules | Yes, within transport limits |
| Storeys | Single, double, triple or more | Set by span and eaves height; confirmed per project | Typically single or stacked |
| Maximum span | Limited by module width | Up to 12 m (ZA); 12 / 15 / 18 m (ZM) | Limited by container width |
| Eaves height | 2.5 / 2.52 m internal | Up to 3.5 m (accommodation/office), 4.5 m (storage); ZM 6 m | Container envelope |
| Design loads | Roof live 1.0 / 0.5 kN/m²; floor live 2.0 kN/m²; wind 0.6 / 0.5 kN/m² | ZA: roof live 0.50 kN/m², wind 0.45 kN/m². ZM: roof live 0.3 / 0.50 kN/m², wind 0.45 / 0.60 kN/m², snow 0.35 / 0.50 kN/m² | Project-specific |
| Service integration | Electrical pre-fitted in roof; water along walls; wall-side drainage | Site-installed within prefabricated structure | Electrical pre-fitted in roof; water along walls; wall-side drainage (CDPH standard module) |
| Typical uses | Engineering camps, commercial buildings, emergency and education facilities, military sites | Accommodation, offices, canteens; warehouses, workshops, storage | Temporary accommodation, site offices, welfare facilities |
| Logistics indicator | Module-dependent | About 200 m² (ZA) or 170 m² (ZM) per 40 ft container | Container envelope |
How to choose: a short selection guide
The decision usually follows from four questions.
- Will the building move? If assets must be recovered and re-erected at a second site, specify modular homes in a detachable or flat pack configuration. Container houses also relocate, within their dimensional limits.
- Do you need clear span? Workshops, warehouses and storage buildings generally need the ZM Series (12 / 15 / 18 m) or the ZA Series (up to 12 m). Volumetric modules are not the right tool for long spans.
- How many storeys? Modular construction stacks to three or more storeys. For the ZA and ZM prefab ranges, the series data fixes spans and eaves heights rather than a storey count, so building height is confirmed per project at engineering review.
- What is the programme and workforce? Erection rates differ materially: four workers erect about 40 m² per day of ZA structure, while ten workers erect about 1,000 m² of ZM structure in five days. Modular installation rates depend on crane access and module count, so they are confirmed at engineering review.
For most camp and facilities projects, the practical answer is a mixed scheme: modular homes for accommodation, offices and welfare units, with prefab wide-span structures for workshops and stores. CDPH reviews layouts on this basis rather than pushing a single product line.
Working with CDPH on a mixed or single-format project
Beijing Chengdong International Modular Housing Corporation was founded in 2009 and operates three production bases in Hebei, Xinjiang and Sichuan; the Hebei base is 48 km from Tianjin Port. The company has 13 subsidiaries and offices, more than 100 engineers and a team of over 500 people, with a reported portfolio of 5,000+ projects in 100+ countries across Eastern Europe, North America, Southeast Asia and Africa. Overseas projects are run through CDPH (HAINAN) COMPANY LIMITED, the wholly-owned subsidiary of the Beijing corporation.
CDPH is a project-based manufacturer: there is no standard MOQ, and every project is quoted individually after engineering review. The engineering team replies within one business day with a concept proposal and a budget range. Certifications held at category level include CE for modular container houses, prefab houses and light steel villas, ISO 14001, ISO 45001, product carbon footprint certification, National High-Tech Enterprise status, NATA materials certification for Australia, Intertek fire-resistance certification, CCS factory approval, Intertek ICC-ES / WH building-material compliance for the US market, and 14 key welders qualified to AWS, CWB and CE standards. Certificates available upon request.
Reference experience at region level includes a port expansion camp in Cote d'Ivoire, a construction camp for a methanol plant, a camp for a cross-sea bridge project in Croatia, a natural gas project camp in Nigeria, a copper mine camp built for −55 °C conditions, and a living camp for a solar power station in Saudi Arabia whose fire performance was verified by Intertek testing.
To discuss which format suits your project, review the modular houses range, see the full product portfolio on the CDPH homepage, or contact the engineering team with your site conditions, layout requirements and destination port. Telephone +86-10 69597331; phone/WhatsApp +86-180 01125803; WhatsApp +86-150 1044 5216; email [email protected]. Head office: No. 8 Art Museum East Street, Xiaobao Art Park, Songzhuang Town, Beijing, China.