The difference between a raised floor and a hollow floor lies mainly in accessibility and construction: with a raised floor, every single panel can be lifted out — the entire void is accessible across the full area. With a hollow floor, access is only possible through defined access hatches. Both systems create an installation space for cables, wiring and climate-control services, but they differ considerably in flexibility, build height and typical applications. This comparison gives planners, architects and facility managers the basis for an informed choice of system.
What is a raised floor?
A raised floor consists of individual, elevated panels resting on height-adjustable pedestals. This creates a continuous, fully accessible void between the structural slab and the floor panels for power, data and climate-control services. The decisive advantage: every panel can be lifted and reinstated individually, so the floor is fully demountable.
Raised floors are standardised under DIN EN 12825, which defines, among other things, load classes. Depending on requirements, versions up to load class 6 are possible, so even high point and area loads can be safely carried. The void height is project-specific and typically ranges from a few centimetres to over a metre. For sensitive areas, ESD-safe coverings can be used to dissipate electrostatic charge in a controlled way.
What is a hollow floor?
A hollow floor is built up in a technically different, and usually lower, way: pedestals are set on the structural slab, onto which non-combustible gypsum-fibre boards are fitted as formwork. A flowable anhydrite screed is then poured over this formwork. Instead of individual loose panels, this creates a closed, monolithic surface. We describe the layer build-up in detail on our service page on the poured hollow floor.
Access to the void is not available across the full area, but only at specific points via defined access hatches. This means the installation space is reachable, but not as flexible as with a raised floor. In return, the hollow floor requires a lower build height and is well suited to areas with manageable future modification needs.
Raised floor vs hollow floor compared
The key differences at a glance:
| Feature | Raised floor | Hollow floor |
|---|---|---|
| Build height | Very large void heights possible | Considerably lower build-up |
| Accessibility | Fully demountable | Only at specific points via access hatches |
| Flexibility & retrofitting | Cabling can be rerouted at any time | Later changes are more involved |
| Loads | Up to load class 6 (DIN EN 12825) | Project-dependent, distributed across the area |
| Surface | Loose individual panels | Closed, poured surface |
Which system for which application?
The raised floor plays to its strengths wherever high cable density and maximum flexibility are required: in data centres, control rooms and office areas with frequently changing technology and workstation layouts. Full-area accessibility makes maintenance, refurbishment and expansion considerably easier.
The hollow floor is the right choice for areas with moderate installation needs and limited build height — for example, large, continuous areas where cabling, once installed, largely stays unchanged and a closed, load-bearing surface is the priority.
In practice, the decision is rarely clear-cut and depends on usage, build height, load requirements and anticipated future changes. Bredo has planned, installed and refurbished both systems nationwide since 1992, and advises you on system choice independently of manufacturer. You can find an overview of our services here — for a specific assessment of your project, please get in touch.
