How long a prefab house lasts is not a single figure — it is the outcome of a structural system, a cladding system and an inspection regime working together. At CDPH, we manufacture prefab houses as engineered assemblies: hot-galvanised cold-formed steel frames, insulated sandwich panel envelopes and factory-controlled connections. The service life of any prefab house is determined by how those materials are specified, how the building is protected against its environment, and how consistently it is inspected and maintained. This page sets out the durability factors procurement teams should evaluate, and the maintenance regime we recommend for the ZA Series, ZM Series and modular house systems.
Durability starts with the structural frame
The governing factor in the lifespan of a prefab house is the steel frame and its corrosion protection. In the ZA and ZM systems, structural columns are cold-formed steel with hot-galvanised corrosion protection; the standard modular frame is galvanised cold-formed steel (SGH340). The ZA Series uses cold-formed T=2–3 mm hot-galvanised columns; the ZM wide-span series uses M300 steel T=3.0 mm hot-galvanised columns with C170 T=2.3 mm hot-galvanised purlins; the modular house frame is galvanised cold-formed steel t=3.0 mm, grade SGH340, factory prefabricated.
Hot-dip galvanising is the core corrosion-resistance measure. Galvanic protection is sacrificial: the zinc coating corrodes preferentially and protects the steel beneath, which is why the coating's condition — not the age of the building — should drive inspection intervals. In coastal, industrial or high-humidity locations, the galvanised layer is the first item to check, and touch-up of any damaged coating is the first maintenance action.
- Frame: cold-formed steel — hot-galvanised columns on the ZA/ZM series; galvanised SGH340 frame on the modular system.
- Bolted connections: inspectable and re-tightenable, supporting extension, reconfiguration and relocation.
- Modular system: modules are bolted together on site and can be relocated and reused.
Envelope and insulation: the weather-facing layer
The envelope takes the weathering, so its specification determines how long the building performs before refurbishment is needed. ZA Series walls are 75 mm colour-steel sandwich panels (white); the roof is 75 mm corrugated colour-steel sandwich panels (blue). The modular house uses 75 mm colour-steel sandwich panels and seamless S-type rock wool composite panels, with 100 mm glass wool insulation in roof and floor. Each panel type has a different failure mode — coating fade and chalking on colour-steel faces, sealant ageing at joints, mechanical damage at handling points — and each is addressed by a different inspection item.
Detailing matters as much as the panel itself. The ZA Series uses a double-pitch roof slope of 1:5, and the ZM Series uses the same 1:5 slope, to shed water promptly. Wall-side drainage is used on the modular system. Correct falls, intact sealant lines and clear drainage paths are what keep water out of the envelope — and water ingress is the most common cause of premature deterioration in any prefab house.
Design loads and environmental limits
Procurement teams should confirm that the specified structural capacity matches the intended service environment. The table below summarises the published design parameters for the three CDPH systems; where a range is shown, the value depends on the configuration selected at engineering review.
| Parameter | ZA Series | ZM Series (wide-span) | Modular house |
|---|---|---|---|
| Structure | Hot-galvanised cold-formed steel columns, T=2–3 mm | M300 steel columns, T=3.0 mm hot-galvanised; C170 purlins, T=2.3 mm | Galvanised cold-formed steel frame, t=3.0 mm, SGH340 |
| Span | Up to 12 m | 12 / 15 / 18 m | Standard modules bolted together |
| Eaves height | Up to 3.5 m (accommodation/office) or 4.5 m (storage), customisable | 6 m | Single, double, triple or more storeys |
| Column spacing | 3.45 m | 4 m or 6 m | Module-based |
| Roof slope | Double-pitch, 1:5 | Double-pitch, 1:5 | — |
| Roof live load | 0.50 kN/m² | 0.3 kN/m² (6 m spacing) or 0.50 kN/m² (4 m spacing) | 1.0 / 0.5 kN/m² |
| Floor live load | — | — | 2.0 kN/m² |
| Wind load | 0.45 kN/m² | 0.45 / 0.60 kN/m² | 0.6 / 0.5 kN/m² |
| Snow load | — | 0.35 / 0.50 kN/m² | — |
| Working temperature | -25 °C to +50 °C | — | — |
These figures are design limits, not wear rates. Operating within the stated loads and temperature range is the condition the design values assume; loading beyond them, or modifying the building without engineering review, takes it outside those assumptions. Design loads are stated per square metre and are configuration-dependent — the project quotation confirms the values for the delivered structure.
Maintenance checklist for prefab houses
No prefab house is maintenance-free, and any supplier who says otherwise is omitting the inspection regime. The following schedule is the practical basis for a site maintenance plan; intervals should be shortened in coastal, dusty or high-wind locations.
Quarterly
- Walk the perimeter and check panel joints, sealant lines and flashings for cracking or separation.
- Clear roof drainage paths and check that the 1:5 roof fall is unobstructed.
- Inspect doors and windows — steel doors 900×2100 mm (customisable), UPVC or aluminium alloy windows — for seal condition and operation.
Annually
- Inspect the galvanised frame at accessible connections for coating damage; touch up any exposed steel.
- Check bolted connections for tightness; the modular system's bolted joints are designed to be re-tightened.
- Inspect wall and roof panel faces for coating fade, chalking or mechanical damage; clean with methods compatible with the colour-steel finish.
- Verify that electrical circuits pre-fitted in the roof and water supply lines along the walls remain secure and undamaged.
After severe weather
- Inspect the envelope and fixings following wind events approaching or exceeding the design wind load.
- Check roof panels and drainage after heavy snow or rainfall.
For relocatable modular units, each disassembly and reassembly is an inspection trigger: check the frame, lifting points and panel edges before the module is re-erected. Because the modules are bolted rather than welded, the building can be dismantled, transported and reused — but reuse depends on the condition of the connections and envelope being verified at each move.
Certification, project evidence and specification support
Durability claims are best supported by third-party verification and by service records in comparable environments. CDPH holds CE marking for modular container houses, prefab houses and light steel villas, ISO 14001 and ISO 45001, product carbon footprint certification and National High-Tech Enterprise status. For export markets, the company holds NATA materials certification for Australia, Intertek fire-resistance certification, CCS factory approval and Intertek ICC-ES / WH building-material compliance for the US market; 14 key welders are qualified to AWS, CWB and CE standards. Certificates available upon request.
Project experience relevant to service-life planning 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. These are camp building references across coastal, industrial, cold-climate and hot-climate regions — the environments that most affect envelope and coating life.
Planning the service life of your prefab house
Beijing Chengdong International Modular Housing Corporation (brand CDPH) has manufactured prefab housing since 2009, operating three production bases in Hebei, Xinjiang and Sichuan; the Hebei base is 48 km from Tianjin Port. The company has 13 subsidiaries and offices, 100+ engineers and a team of 500+ people, with a reported portfolio of 5,000+ projects in 100+ countries across Eastern Europe, North America, Southeast Asia and Africa. Overseas projects 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. To discuss the right system and maintenance plan for your site, review the prefabricated houses range, see the full product portfolio on our home page, or contact the engineering team with your project parameters. Certificates are available upon request, and each project is quoted individually after engineering review.
Choosing a Prefab House System That Supports Long-Term Durability
Because the working life of a prefab houses depends heavily on the structure and envelope you start with, the specification stage is where lasting performance is decided. The CDPH range illustrates how requirements map onto different systems, so buyers can match a model to climate, use and maintenance expectations rather than defaulting to one type.
For accommodation and office buildings, the ZA Series uses a cold-formed steel frame with hot-galvanised columns (T=2–3 mm) and 75 mm colour-steel sandwich wall and roof panels — a combination that resists corrosion and provides good thermal insulation. Spans reach 12 m, eaves height up to 3.5 m, with column spacing of 3.45 m and a 1:5 roof slope; it is rated for roof live load of 0.50 kN/m², wind load of 0.45 kN/m² and working temperatures from -25 °C to +50 °C. Where wider clear space is needed, the ZM Series spans 12, 15 or 18 m with 6 m eaves, M300 hot-galvanised columns and C170 purlins, and lists snow load ratings of 0.35 or 0.50 kN/m² in the series data.
Modular units take a different path to longevity: galvanised cold-formed steel frames (t=3.0 mm, SGH340) prefabricated in the factory, 100 mm glass wool roof and floor insulation, and bolted connections that allow relocation and reuse. This is a decisive maintenance advantage — modules can later be dismantled, moved and re-erected instead of abandoned.
Two practical points support a long service life from day one:
- Confirm design loads against local wind and snow conditions; the ZM Series pairs its roof live load rating with column spacing (0.50 kN/m² at 4 m spacing, 0.3 kN/m² at 6 m); its wind ratings are listed separately in the series data.
- Plan access for panel and roof inspection, since sandwich panels and galvanised steel perform best when coatings and seals are checked and renewed periodically.
Manufacturing context matters too: CDPH was founded in 2009 and operates three production bases (Hebei, Xinjiang, Sichuan), with the Hebei base 48 km from Tianjin Port — helpful when large structures ship as roughly 200 m² (ZA) or 170 m² (ZM) per 40 ft container. Certificates covering CE, ISO 14001, ISO 45001 and Intertek fire-resistance certification are available upon request.