Ask several Chinese suppliers to quote a 20ft expandable house, and you may receive similar-looking designs at very different prices.
The photographs may all show a living room, bedrooms, a kitchen and a bathroom. The specifications may mention steel framing, insulated panels, double glazing and pre-installed services. To compare the offers properly, buyers need to examine the drawings, material schedules, construction details and scope of delivery.
For importers, distributors and project buyers, the practical question is whether the supplier can consistently deliver the agreed house configuration and provide the information needed to install and maintain it. That assessment starts with the first enquiry.
Give the manufacturer a clear project brief
An expandable house intended for seasonal accommodation may have different requirements from one planned for long-term residential use. Similar floor areas and exterior designs can conceal substantial differences in insulation, structural requirements, equipment and supporting documentation.
Include the project location, intended use, quantity, occupancy and site conditions in your enquiry. Share any requirements already identified by your local engineer or approval team.
Explain the purchasing plan as well: a single trial unit, a sample followed by a larger order, or repeat shipments of an agreed model. This helps the supplier propose a suitable configuration and schedule.
Questions about the location, transport route and installation arrangements are part of technical clarification. If the discussion remains limited to “20ft, two bedrooms, kitchen and bathroom,” the specification is still incomplete.
Compare quotations against the same specification
Before comparing prices, establish what each quotation includes.
| Item | Details to confirm |
|---|---|
| Dimensions and floor area | Folded dimensions, expanded dimensions, internal clear dimensions and the basis used to calculate floor area |
| Steel structure | Main member locations, section sizes, wall thicknesses, material grades and connection details |
| Roof, walls and floor | Material layers, thicknesses and junction details |
| Doors and windows | Frame material, glazing configuration, opening type, seals and installation details |
| Kitchen and bathroom | Included equipment, quantities, brands or models, and extent of factory installation |
| Electrical and plumbing systems | Component schedule, connection locations and project requirements |
| External accessories | Whether decks, canopies, additional roofs and steps are included |
| Technical support | Scope of drawings, structural documentation and installation guidance |
| Shipping and site work | Loading arrangement, unloading requirements and responsibilities for site assembly and connections |
A “50mm wall panel” description gives one dimension. It does not identify the core, facing sheets, joints or installation method. “Double glazing” also leaves several parts of the window specification unanswered.
Options that affect cost should appear in the final material schedule or drawings. Any substitution should be recorded and agreed before it is used in production.
For a broader discussion of manufacturing and engineering costs, see our expandable house industry analysis.
Ask how the expanded structure is supported
An expandable house passes through folding, transport, unloading and deployment before use. Buyers need to understand how its parts connect and how the expanded structure is supported.
Ask the manufacturer to explain the following for the model being quoted:
How the central module connects to the two expanding sections.
Which members support the expanded floor and roof.
Where supports are required and what the site must provide.
How door openings, window openings and larger open spaces are addressed.
Where the designated lifting or handling points are and which instructions apply.
These questions turn a general description such as “strong steel structure” into construction details that can be reviewed.
Steel thickness should also be tied to a particular member. Main beams, columns, secondary members and decorative parts serve different purposes. An advertisement referring to “3mm steel” does not describe the complete frame.
Where wind and snow requirements are specified, check that the structural information matches the ordered model, dimensions, members and support arrangement.
Read wind and snow figures alongside the structural configuration
Buyers often ask how much wind or snow an expandable house can withstand. A useful answer identifies the input conditions, the structure assessed and the resulting response. Wind speed, applied pressure, member stress and displacement describe different parts of that assessment.
In 2024, ReachTop carried out a structural analysis of an ordinary expandable house design. That design has since been retired from our product range. Its results still provide a useful example of how buyers can read structural performance information.
The analysis used a wind-speed input of 150 mph and applied a pressure of 2.8 kPa separately in two directions. The roof snow-load case used 65 psf, approximately 3.1 kPa.
| Analysis case | Maximum equivalent stress | Maximum displacement |
|---|---|---|
| X-direction wind load | 107 MPa | 4.6 mm |
| Y-direction wind load | 101 MPa | 3.6 mm |
| Roof snow load | 232 MPa | 10.7 mm |
These results relate to the structural model, materials and support conditions used in that analysis. During procurement, performance information should likewise be matched to the structure being ordered.
The load cases and results are explained in our expandable house wind and snow load analysis.
Confirm site installation conditions before production
A house that opens correctly at the factory still needs an appropriate unloading and installation arrangement at its destination.
While the manufacturer confirms the structure and layout, check whether the delivery vehicle can reach the site, whether unloading equipment can operate there, and whether enough space is available to unfold the house. Coordinate the foundation and support positions with the project team.
Drainage, electricity and water connections also need to match the site arrangements.
Ask what “installation complete” means in the quotation. The scope may cover deployment and fixing, or it may include selected joints, accessories and service connections. Obtain a work schedule identifying factory-installed items, work required after transport and tasks for local contractors.
This provides a workable basis for arranging labour, equipment and time.
Inspect the junctions as well as the insulation and finishes
A material schedule helps buyers compare components. Detail photographs and construction drawings show how those components fit together.
For the roof, examine drainage direction, joints, penetrations and areas that require attention after deployment. For windows, examine the frame-to-wall connection, sealing details and drainage provisions.
Projects with demanding insulation requirements should consider the roof, walls, floor and windows together. Indoor conditions are also influenced by joints, air leakage, ventilation and heating or cooling equipment.
Resolve these points during configuration and sample approval. Changing windows or adding insulation after delivery can create additional purchasing and site work.
Match each technical document to the ordered house
A supplier may provide material information, component documents, structural analysis, drawings and inspection records. Buyers need to understand what each document covers.
| Document | What to check |
|---|---|
| Structural analysis or calculations | Model, dimensions, structural revision, design conditions and corresponding drawings |
| Material or component information | Brand, model and specification against the order schedule |
| Product drawings | Agreed layout, dimensions, connection locations and revision |
| Inspection records | Identified units or batch, inspection items and results |
| Installation instructions | Applicability to the ordered house and accessories, with clear site procedures |
For projects requiring local approvals, ask the relevant local professionals to identify document needs early, then coordinate those requirements with the manufacturer.
Early review allows the specification to be settled before production. Requests for different structural details or materials become more complicated once the house has been built.
Follow one house through the factory
Factory size and equipment provide context. For an actual order, it is useful to understand how a house moves between production stages.
Start with steel fabrication and continue through surface treatment, panel installation, windows, services and interior fit-out. Ask which operations are completed in-house, which components come from outside suppliers and how incoming specifications are checked.
A useful question at each stage is: which drawing revision and configuration sheet is being used for this house?
The answer leads to material identification, change instructions, inspection records and rework procedures. Buyers do not need to master every manufacturing process to assess whether an order has clear production instructions.
If a factory visit is impractical, request a video review focused on the actual order. Include the frame under construction, important connections and assembly stages alongside the finished interior.
Turn sample approval into a repeat-order specification
A sample house can confirm appearance, layout and selected functions. Repeat purchasing also requires a way to maintain the approved configuration.
After approval, retain the final layout, material schedule, equipment models, colours, detail photographs and accepted changes. Bulk orders should refer to the relevant revision of those documents.
For phased deliveries, agree how changes to materials or components will be handled. A replacement that looks similar may have a different specification.
The first delivery also tests the packaging and installation information. Record issues found on site so that later batches have a clear basis for improvement.
Schedule inspections while problems can still be corrected
Inspection requirements should follow the order configuration. They can cover dimensions, appearance, deployment, doors, windows, equipment, connections and accessories.
| Inspection stage | Checks to agree in advance |
|---|---|
| Dimensions and layout | Room, opening, equipment and connection positions against approved drawings |
| Deployment and refolding | Operation, required tools and personnel |
| Doors, windows and finishes | Opening and closing, locks, junctions and fixing |
| Services and equipment | Agreed functional checks and records |
| Water-related details | Inspection scope, test method and follow-up for any issues |
| Packing and accessories | Loose parts, installation materials, documents and packing list |
If a third-party inspection is planned, inform the manufacturer of its scope and timing in advance.
Some details become concealed during fit-out; other items are difficult to correct after loading. Include important checks in the production schedule so they can be completed at an appropriate stage.
Calculate transport and site costs alongside the house price
The purchase price is one part of the project budget. Depending on the delivery scope, buyers may also need to account for shipping, destination charges, local transport, unloading, foundations, installation, service connections and accessory work.
Confirm responsibility for each item in the quotation and delivery arrangements.
For expandable houses, loading plans deserve early attention. Folded dimensions, model combinations and accessories affect the space needed. Decks, additional roofs, furniture and spare parts may require separate allowance.
The stated loading quantity should match the actual order configuration. Use that plan to obtain freight quotations, then combine transport and site costs when comparing offers.
Make after-sales support specific
For overseas orders, establish how replacement parts and technical enquiries will be handled before purchasing.
Which components can be sourced locally? Which need to come from the manufacturer? What photographs or identification details are needed to investigate a problem? How will replacement parts be identified, priced and shipped?
Distributors selling a product series over time also need to distinguish different batches of windows, locks, seals and equipment. Keeping model references, component schedules and drawings with the delivery records reduces later identification work.
Use three decision points before committing to a bulk order
During initial screening, establish whether the supplier understands the project, offers a suitable product and can explain the quotation in sufficient detail.
During technical confirmation, settle the layout, materials, structural conditions, documentation and installation arrangements. If a sample is needed, agree how it will be assessed.
Before bulk production, confirm the approved revision, production schedule, inspection arrangements, loading plan and after-sales responsibilities.
Each stage should produce information that can be used in the next. The decision then progresses from a website introduction to an order that both parties can execute.
Frequently Asked Questions
Do I need a complete technical package before contacting a manufacturer?
Start with the project location, intended use, quantity, preferred layout and site photographs. Include existing engineering requirements or approval comments. The supplier can use this information for initial selection, then work with you to complete the quotation and production requirements.
Why can two 20ft, two-bedroom houses have very different prices?
Size and bedroom count do not define the frame, panels, windows, equipment or delivery scope. Compare those items against the same specification to understand what accounts for the difference.
Can a supplier’s existing structural data be used for my model?
Check the model, structural revision, dimensions, materials and support conditions against your order and project requirements. Where the layout or members change, the responsible technical team should determine what additional review is needed.
What should I check when ordering a sample house?
Alongside the interior and appearance, review packing, unloading, deployment, site connections, accessory completeness and the usefulness of the installation instructions. Keep the approved sample and documents as references for later orders.
How can I start evaluating an expandable house from ReachTop?
Browse the ReachTop expandable container house range to identify a suitable size and layout. Then provide the project location, intended use, quantity and existing technical requirements so that materials, structure, transport and site work can be reviewed together.
