MARTETIC technical guide
Container foundation on screw piles: what to prepare before delivery
You have chosen the container and you have a delivery date. The next step is to prepare a foundation compatible with its chassis, with the unloading access and with the level at which you want the floor.
Direct answer
The foundation of a modular container is prepared starting from the manufacturer's support plan. The position of the supports, the loads, the levels and the anchoring must be correlated with the ground on site. Dimensions of 6 × 3 m or 8 × 3 m do not by themselves determine the number and model of the screws.
Modular container or shipping container?
Two buildings with the same outline can have different chassis. A shipping container, a module made as an office and a container converted into a dwelling must not be treated as identical structural products.
For a module, the manufacturer may require intermediate supports under the longitudinal beams. For a modified container, cutting the walls for windows and doors, or joining several units, can change the behaviour of the structure. Ask for the documentation for the configuration you are buying, including the ordered modifications.
As an example, the CONTAINEX CLASSIC Line documentation specifies, for certain 16 ft and 20 ft modules, at least six support points. The requirement belongs to that range and shows why the four-corner rule cannot be applied to all containers. See the manufacturer's documentation, section 8.3.
What to ask the container manufacturer for
| Document or information | What it is used for |
|---|---|
| Dimensioned plan of the supports | Shows the positions where the chassis accepts support. |
| Support reactions and load cases | Allow the designer to check the load on each point. |
| Detail of the chassis and the fixings | Determines the contact surface, the connections and the anchoring. |
| Levels of the connections and the floor | Help coordinate the foundation with the services and access. |
| Permitted tolerances and installation instructions | Set the acceptance conditions before unloading. |
If you only have a commercial offer and a photograph, we can start the discussion about the budget. For execution, the structural data must be completed. A total mass declared in the commercial sheet does not describe all the loads in service.
Where the screws go
Each support must meet an element of the chassis that can take that support. Adding a point under a thin area of the floor can cause a local problem, even if the intention was to stiffen the container.
Some projects allow direct connection to the screw heads. Others need distribution beams, plates or parts made for that chassis. These components are set before delivery, together with the way of fixing against displacement and uplift.
For the principles of laying out the grid, read how the number of foundation screws is determined.
Set the finished floor level before installation
Note separately the level of the finished ground, the level of the support and the level of the finished floor. Between the screw head and the floor, the connecting parts and the height of the chassis come into the calculation.
This coordination affects the steps, the link with the terrace and the space available for drainage. If the terrace is designed later, there is a risk that it ends up at an unsuitable level relative to the door.
The space under the module is detailed for water, ventilation, protection of the services and maintenance access. A decorative closure of the plinth must not block the functions provided for by the designer and the manufacturer.
Coordinate the foundation with transport and the crane
Confirm the truck's route, its standing position, the crane's position and the order of the modules. A small machine can reach the foundation by a route the delivery truck cannot use.
Sending a continuous video from the public road to the site helps identify tight bends, gates and overhead cables. The crane's position and capacity are determined by the operator for the real lifting distance and the ground conditions.
Schedule the placement of the container after the foundation has been checked and accepted. Don't tie the transport to a generic promise of installation in a single day.
What to check before the module arrives
- The plan used for the foundation is the same revision as the plan for the container ordered.
- The measured positions and levels fall within the tolerances set for the project.
- The connections, the fixings and any beams are prepared.
- The planned checks and tests have been completed and documented.
- The utility routes and connection openings are coordinated.
- There is a person who confirms acceptance of the foundation before delivery.
For an assembly with a terrace, acceptance must also look at the relationship between the bodies, the joints and the access. A small error repeated between modules can complicate the joints.
What to send to MARTETIC
Send the locality, the container plan, the documents received from the manufacturer, photographs of the access and the available geotechnical information. Specify whether you want supply of screws, supply with installation, or also the connecting structure.
For the preliminary budget you can consult the foundation cost guide. The project's offer must specify separately the transport, installation, connections and the technical services needed.
Frequently asked questions
Can a 6 × 3 m container be placed on four screws?
Only if the structural scheme and the project's checks allow that configuration. The external dimension does not confirm the number of supports.
Can I order the screws before choosing the container manufacturer?
You can consult the range and the budgets, but the final selection needs the chassis and the real foundation conditions. Otherwise, there is a risk of buying unsuitable products or connections.
Can the container be placed immediately after the foundation?
After acceptance of the installation, the connections and the checks provided for in the project, the placement can be scheduled. Screws have no curing period of their own.
Can I use the same foundation for two container models?
Compatibility must be checked for each model. The support positions, loads and connections can change even if the dimensions are close.
What does a container foundation on screw piles need before delivery?
The support positions must match the container's chassis, the levels and access (crane or delivery truck) must be confirmed, and the delivery must be coordinated with the foundation works and the agreed documents.
Does every container need the same number of screw piles?
No. The number of points is determined for the specific chassis and site. For example, a container of about 6 × 3 m on one MARTETIC project was supported on 8 screws, which does not mean that every container of that size needs 8.
Can a container sit on screw piles instead of concrete?
Yes, screw pile foundations are used for containers and modular units. The foundation type does not, however, change the authorisation requirements for the building.
Prepare the foundation before the container is delivered
Send the support plan, the locality and the estimated delivery date. We can determine what further information is needed and what must be included in the offer.
The information explains how a project is prepared and is not an execution plan. The solution is determined for the real building and site, on the basis of the applicable documentation and the project's checks.