Monolithischer Hohlraumboden The monolithic cavity floor
Cavity floor systems for underfloor trunking have proven very successful in modern administration buildings. They meet the wishes of the builder-owner and his tenants for generous room design and flexible room occupancy and offer virtually unrestricted space for computer, telecommunication and electrical cables.


The System
The Inter Flexa-cavtyfloor is a floor system for anhydrite jointless floating and cement screed of monolithic design with a jointless and absolutely smooth and level surface. Despite only a thin screed topping, the large unobstructed cross-section allows flexible underfloor trunking of cables for building installation practice and electrical engineering in all directions.
Owing to its arched design, floor features a very high load-carrying capacity well above the live loads occurring in administration buildings. Without the need for further measures, non-load-bearing interior partition wall systems can be installed acoustically tightly sealed and any type of floor covering can be laid.
The arched cavity is formed from split-duct elements with deep-drawn support feet made of polystyrene film. The elements are bonded together. After laying, the formwork is topped up in one operation with self-levelling anhydrite jointless floating and cement screed and filled to the required level.

The film formwork adapts flexibly to irregular unfinished floors so that the support feet are always in contact with the unfinished floor. The irregularities of the unfinished floor are compensated for by corresponding extra thicknesses of the screed panel.

The formwork film is joined to facades and walls with special edge strips.
Recesses for electrical or ventilation openings are made with deep-drawn shaped fittings. However, they can also be drilled subsequently in the finished screed. Combining with false floor elements and inspection frames poses no problems.

The floor features very good sound reduction indices and is also used for air ducting. The unfinished floor is sealed with a dustcoat for this purpose. The formwork film consists of hygienic materials and poses no problems as regards fire protection since no fire can develop owing to oxygen deficiency as the result of its density.


Technical data

Support foot spacing: 200 mm
Formwork element: 600 x 2400 mm

Type Clear high in mm Total high* ( not including top covering) in mm

Weight* withscreed panel in kg/ml

FM40 40 70 74,5
FM50 50 80 75,5
FM60 60 90 76,5
FM70 70 100 77,5
FM80 80 110 78,5
FM90 90 120 79,5
FM100 100 130 80,5
FM110 110 140 81,5
FM120 120 150 82,5
FM130 130 160 83,5

*) 40 mm floating screed, 2,1 kg/l


Qualität Quality
Inter Flexa-cavity floor, made of formwork elements and anhydrite jointless floating or cement screed forms a tested and quality-assured unit. The load-bearing capacity of Inter Flexa-cavity floor is determined by the screed thickness and by the floor system. Permitted values for point load, strip load and area load apply to a screed thickness of 40 mm measured above the crest between two support feet.



Airborne sound insulation

Horizontal RL, w 50 dB
Horizontal with expansion joint RL, w 59 dB
Vertikal* Rw 53-55 dB

Footstep sound insulation**

Horizontal Ln, w (TSM) 85 dB (-22 dB)
Horizontal with expansion joint Ln, w (TSM) 54 dB (+9 dB)
Horizontal with expansion joint and carpet Ln, w (TSM) 41 dB (+22 dB)
Vertikal A Lw 10 dB
Vertikal with carpet A Lw 31 dB

*) 15 cm concrete thickness

**) In the case of footstep sound insulation, the values are dependent on the enhancement factor of the top floor covering. The dimensions refer to 40 mm screed.




Copyright © 2001 Inter Flexa AG