Modular or conventional construction? A comparison
Pacarada Modular Building Systems, Kelkheim (Taunus), Germany · Last updated: September 2026
In conventional construction a building is created layer by layer on site. In modular construction most of it is prefabricated in the factory and assembled on site. The difference lies less in the finished building than in how it gets there: modular construction is usually faster, more predictable and less dependent on the weather, but it requires earlier and more precise planning.
How a conventional project works
On site the trades work largely one after another: shell, roof, windows, building services, interior fit-out. Each step depends on the previous one, on the weather and on whether the skilled workers needed are available. If one trade is delayed, every subsequent trade is pushed back.
How a modular project works
In modular construction two strands run in parallel. While foundations and connections are built on site, components and room modules are manufactured in the factory under constant conditions, with a quality check before delivery. On site the modules are then placed, joined and connected to the services.
In the Pacarada Modular Building System the components are joined at the Cube, an internationally patented steel connection node. Columns, beams, wall and floor elements and complete room modules are bolted and plugged to it, not welded. The electrical installation is also a plug-in system as in the automotive industry and is prepared in the factory.
The comparison at a glance
| Criterion | Conventional | Modular |
|---|---|---|
| Where the work happens | Mostly on site | Mostly in the factory, assembly on site |
| Process | Trades largely one after another | Factory production and site work in parallel |
| Weather | Affects many work steps | Mainly affects assembly |
| Skilled workers on site | Many trades over a long period | Fewer people over a shorter period |
| Quality control | On site, often under time pressure | In the factory, before delivery |
| Design changes | Possible at a late stage, but costly | Should be fixed before production starts |
| Impact on neighbours | Throughout the construction period | Mainly during the shorter assembly phase |
| End of life | Demolition, components rarely reusable | Bolted in the Pacarada system: demountable and reusable |
Where modular construction is strongest
Wherever time, repetition and predictability matter: housing and student accommodation, schools and nurseries, care and healthcare buildings, hotels and offices. Added storeys and extensions also benefit, because the work on the existing building stays short.
Darmstadt example: Converting a vacant office building at Holzhofallee 36 into 197 homes, with bathroom modules, an extension and added storeys, took 18 months (09/2021 to 02/2023). That was 44% faster than conventional construction. The building meets the KfW 55 standard.
Where the limits are
Modular construction is not automatically the right answer. The design must be finalised earlier, because factory production is based on fixed drawings. The size of room modules is limited by road transport, and assembly needs site access and space for a crane. A modular building usually also needs a building permit and must meet the same requirements for structural safety, fire protection, sound and thermal insulation as any other building.
The Pacarada system answers the transport limit with three construction methods: where complete room modules (3D) do not fit, columns and beams (1D) or wall and floor elements (2D) are used, all connected at the same Cube. This also makes large open spaces possible.
Frequently asked questions
Is a modular building as permanent as a conventional one?
A modular building designed to be permanent, whether steel, timber or concrete, is neither a container nor a temporary structure. It must meet the same requirements for structural safety, fire protection, sound and thermal insulation as a conventionally built one. The difference lies in how it is made.
Can you tell that a building is modular?
Not necessarily. Architects and engineers design the facade, roof and floor plans freely; the modules and components are then made in the factory.
Which projects benefit most from modular construction?
Buildings with many similar rooms, such as apartments, student flats, classrooms, care rooms or hotel rooms, and any project where construction time and predictability matter, including added storeys and extensions. Our article on the cost of modular construction explains which factors decide the cost.
More articles in the modular building guide
- Adding storeys and extensions with modular construction
- Modular schools and nurseries
- Steel modular and hybrid construction: steel, timber and concrete combined
- What drives the cost of modular construction
- Back to the overview: modular building guide
Planning a project? Send us your enquiry, ideally with drawings. You will find all system data on our Facts and figures page.