A modular house is a residential building made of one or more steel modules that are manufactured in a production hall and then placed and joined on site. It is neither a site cabin nor a temporary shelter: the modules are designed around the layout, insulation and technical equipment of a specific project and can be joined side by side, end to end and on top of each other. At RIKOSTAV CONTAINER we have been producing modular buildings and containers to order for two decades, and experience tells us that the quality of living is not decided by the word “modular” or “container” in the name, but by the structure, the insulation, the foundations and what the delivery actually includes. This article explains how a modular house is built, how it differs from a container house, what sizes and layouts are realistic, what drives the price, how the project runs, what has to be ready on the plot, which regulations apply and when this solution is not worth it.
[Image: Two-storey modular family house made of steel modules with large glazed areas and a terrace, set on footings on a flat plot, front view. Alt text: Modular house made of steel modules with terrace and glazing]
A modular house is built from steel modules made in a hall
The core of every module is a self-supporting steel frame to which the floor, external walls and roof are attached. The frame carries the whole building, so it makes no difference whether the module stands alone or is part of a larger assembly. The walls, floor and roof are layered build-ups in which the thickness and type of insulation, the surfaces and the position of openings follow the purpose of the building. A weekend cottage and a house for year-round living share the same frame principle but have completely different wall build-ups. How a module is built layer by layer is described on our page about the technology of our modules.
Production in a hall is the main difference from masonry construction. The structure, insulation, windows, services and the agreed fit-out are built under a roof, in stable conditions and with continuous inspection. A finished or nearly finished module is then transported to the plot, and assembly takes days rather than months. Weather and the building site stop being a scheduling risk. It also means that most decisions are made before production, not during it: moving a window in a finished module costs more than moving it on a drawing.
A container house and a modular house are not the same thing
The terms are used interchangeably in everyday speech, but it pays to distinguish them when deciding. A container house is usually a simplified name for a building made of container elements, often with dimensions derived from shipping containers. A modular house is a broader method of construction: the modules are made to a design, and their size, wall build-up and openings are a matter of planning, not of transport standards. The customer should therefore not ask what the building is called, but what it is made of.
| Criterion | Container house (shipping container) | Custom modular house |
|---|---|---|
| Module size | set by the shipping container standard | according to the design, in our case up to 12 × 3.99 × 3.37 m |
| Structure | corrugated sheet as the load-bearing wall | self-supporting steel frame, walls are a layered build-up |
| Insulation | added afterwards, reduces interior space | part of the wall, floor and roof build-up |
| Openings and glazing | limited by the sheet-metal statics | designed in advance, including large glazed areas |
| Several storeys | limited | up to three storeys after structural assessment |
| Future extension | complicated | possible if the design allows for it |
Comparison of a typical building made of shipping containers and a modular house manufactured to a design.
The size of the house is not set by the size of one module
The most common worry is that a modular house will be narrow and small. In custom production one module can measure up to roughly 12 × 3.99 × 3.37 m, and modules are joined side by side, end to end and on top of each other. The resulting floor area is therefore limited not by one module but by the design, the plot and the budget. For multi-storey designs we carry out an individual structural assessment; the system allows solutions of up to three storeys. The design adapts to the layout, not the layout to the module.
The layout follows from the number of occupants, the shape of the plot and how the house will be used. Three types of brief keep recurring in our projects:
- House for one person or a couple: living room with kitchen, bedroom, bathroom and utility space, usually one or two modules.
- House for 3 to 4 people: living area with kitchen, 2 to 3 bedrooms, bathroom, separate toilet, utility room and storage, usually three or four modules side by side or in an L shape.
- Larger house or two storeys: ground floor with living area, kitchen, utility room and toilet; upper floor with bedrooms, a second bathroom, a study and a walk-in wardrobe; possibly a terrace and storage.
What such briefs look like when finished is shown by the family houses and cottages we have built. The actual layout, however, always follows from the design and the technical possibilities of the building, not from a catalogue floor plan.
The price of a modular house is set by the scope of delivery, not the number of modules
The question “how much does a modular house cost” has no single-number answer, and anyone who gives one without a brief is guessing. Two houses with the same number of modules can differ in price by tens of percent depending on what the delivery includes. When comparing offers, therefore, do not compare the price per module but the list of what is included and what you will have to arrange yourself. The most frequent differences between offers are in these items:
| Group | What affects the price | What to ask |
|---|---|---|
| Scope of the building | floor area, number and size of modules, number of storeys, layout | Is the structural assessment for two or more storeys included? |
| Envelope | type and thickness of insulation, windows and doors, facade, roof | What are the insulation values in the wall, floor and roof? |
| Services | electrical installation, heating and cooling, sanitary fittings, connection preparation | Is the bathroom and kitchen plumbing included, or only the preparation? |
| Plot | foundations, access for truck and crane, drainage, utility connections | Who provides the foundations and connections? |
| Logistics | transport, crane, assembly, joining of modules | Are transport and assembly in the offer or charged separately? |
| Documentation | permit design, structural design, energy assessment | Which documents will I receive and who prepares them? |
Items that change the final price of a modular house the most in practice.
It is not true that a modular house is automatically cheaper than a masonry one. The advantage lies elsewhere: the scope of production is controlled, less work takes place on the plot and the schedule is more predictable. Savings come mainly from the shorter construction time and from paying for a clearly defined scope. Anyone who only looks for the lowest price per module often ends up with a bare structure and pays for the rest on site.
The project runs in six steps
The customer does not need a finished design at the start. For the first consultation a basic idea of the purpose, approximate size, location and deadline is enough; a floor plan or sketch helps but is not required. The rest of the process is well established:
- Brief: who the house is for, how many people will live in it, approximate area, number of rooms, location, deadline and an idea of the fit-out.
- Layout design: number and size of modules, how they connect and the interior arrangement.
- Design and technical solution: structural design, build-ups, utility connections, foundations and documents for the permit procedure.
- Production of the modules in the hall: structure, insulation, windows, services and the agreed fit-out.
- Preparation of the plot: foundations, connections and access, arranged according to the design before transport.
- Transport and assembly: placement by crane or hydraulic arm, joining of modules, finishing of joints and connection to utilities.
The plot must be ready before the modules arrive
The most common mistake we see is dealing with the house and leaving the plot to the end. Before placement, the foundation must be finished, the electricity, water and sewer connections or another wastewater solution must be ready, and drainage and access for the truck and crane, which need more room than the module itself, must be sorted out. The module must sit level and away from standing water. Depending on the size of the building and the subsoil, we found on concrete blocks, footings, strip foundations or ground screws; exactly what has to be ready and what the customer usually provides is agreed in the design and checked before transport.
Permits are part of the preparation too. A family house for permanent living is not a minor structure, even when it is modular. Slovak Building Act No. 25/2025 Coll., in force since 1 April 2025, defines a minor structure as a building that cannot substantially affect its surroundings (§ 2 of the Act, in Slovak) and, for single-storey buildings, limits it to a built-up area of 50 m² and a height of 5 m. A family house exceeds these limits, so expect a permit procedure and a design as with any other building. A modular house is not a shortcut around the building authority. Act No. 555/2005 Coll. on the energy performance of buildings applies equally: under § 4b, all new buildings must meet the requirements for nearly zero-energy buildings from 31 December 2020, which directly determines the insulation thickness and window quality in the module build-up. That demand for family housing is not falling is shown by data from the Statistical Office of the Slovak Republic: according to a TASR report from September 2024, dwellings in family houses accounted for 65% of all dwellings completed in the second quarter of 2024.
When a modular house is not worth it
Modular construction is not a universal answer. It is not worth it on a plot that a truck with a crane cannot reach, because alternative logistics eat up the savings from production. Nor is it worth it when the customer wants to decide on details during construction: the modules are made to the design and changes after production are expensive. And it makes no sense if someone expects to bypass the design, the structural assessment or the energy requirements; they apply exactly as they do to a masonry house.
In our experience the most satisfied customers are those who came with a clear brief and a plot prepared according to the design. The most time and money is lost on changes that arise only once the modules are standing on site.
On the other hand, a modular house is strong where time, a predictable scope and the option of extending the house later matter. A young family can start with a smaller assembly and add further modules years later, provided the design and structural solution allowed for it. The same principle suits a weekend house, a guest house or a separate dwelling unit next to an existing home, always subject to the design and the permit conditions.
Questions to put to every supplier before ordering
Not every residential module is the same. The steel frame alone is only the structural base, and comfort is decided by the whole system: structure, insulation, windows and doors, services, layout, foundations, assembly and utility connections. Before signing, ask for answers on these points:
- Structure: what material forms the load-bearing system and how it is protected against corrosion.
- Insulation: what build-up and thickness is in the walls, floor and roof and whether it meets the requirements for a new building.
- Layout: whether the floor plan can be adapted to your needs and where the limits are.
- Services: exactly what is included in the price: electrical installation, heating, sanitary fittings, connection preparation.
- Transport and assembly: whether they are part of the offer and who is responsible for joining the modules.
- Foundations: what type of foundation the building requires and who provides it.
- Documentation: what design and technical documents you will receive.
- Extension: whether the design allows for adding modules in the future.
At RIKOSTAV CONTAINER we offer standard assemblies as well as custom buildings; for your own project a basic idea of the purpose, size and location is enough for the first consultation, and based on the brief we prepare a proposal for the number of modules, their dimensions, the layout and the fit-out.
Frequently asked questions
How much does a modular house cost?
The price depends on the floor area, the number and size of modules, the layout, insulation, windows, services, surfaces, foundations, transport and assembly. An exact price can only be set on the basis of a specific brief, so compare the scope of delivery rather than the price per module.
Is a modular house cheaper than a masonry house?
Not automatically. The advantages are a controlled scope of production, a shorter construction time and less work on the plot. For two similar houses the price difference is mostly determined by what the delivery includes.
Can a family house be built from several modules?
Yes. Modules are joined side by side, end to end and on top of each other according to the design, so the floor area is not limited by the size of one module.
How large can one module be?
In custom production one module can measure up to roughly 12 × 3.99 × 3.37 m. The overall size of the house comes from combining several modules.
Is it possible to build a two-storey or multi-storey modular house?
Yes, the system allows individual designs of up to three storeys. A multi-storey solution always requires a structural assessment.
Can a modular house be extended later?
Yes, if the design and the structural solution allow for it. A future extension has to be taken into account at the design stage, not after placement.
Do I need a building permit for a modular house?
Yes. A family house for living exceeds the limits of a minor structure under Slovak Building Act No. 25/2025 Coll., so a permit procedure applies and a design, structural assessment and compliance with energy requirements are needed as for any other building.
Is a modular house suitable for permanent living?
Yes, if it is designed for year-round use: with wall, floor and roof build-ups for a new building, suitable heating and foundations according to the design. The technical execution decides, not the name of the building.
What has to be ready on the plot before placement?
Foundations according to the design, electricity, water and sewer connections or another wastewater solution, drainage and access for the truck and crane. The module must sit level and away from standing water.
Do I need a finished design before the first consultation?
No. A basic idea of the purpose, approximate size, number of rooms, location and deadline is enough. The design and technical solution are developed once the brief is agreed.