The present invention relates to a prefabricated floor separator for mounting over large spans.

For buildings constructed in steel / concrete "hollow concrete layer" is often used to separate floors. The hollow concrete layer is delivered as precasted elements that are mounted on the building site. This type of building element have clear advantages regarding span, good sound technical properties, competitive price, and have obtained a strong market position. However, the disadvantageous of the "hollow concrete layer" are that the elements do not give a satisfactory smooth and plane surface. This must be compensated for by applying a paste for casting or levelling. This process, together with the following drying process, cause time and cost disadvantages. Furthermore, such elements become heavy, creating a need for dimensioning of foundation and support system accordingly. It have also been shown that hollow concrete layers often have caused moisture problem in that rain water has entered /leaked into the voids of the element, and has not been released before inbuilding. To avoid this there may be a need for product-related adjustments or mounting-related procedures that will produce additional costs.

For constructions mainly based on wood the floors are most often based on timber work solutions. Timber work solutions have clear limitations regarding spans. Furthermore, they have poorer sound technical properties and are most often constructed on site. It would have been an advantage for parties working with construction of wooden buildings to have a "hollow wood layer", in replacement of "hollow concrete layer" found in the concrete sector. Among the important functional properties that such a "hollow wood layer" should have one may mention larger spans having increased possibilities for flexible layouts, low weight, better sound technical properties, give room for infrastructure such as water, drainage, ventilation, etc., remanufactured elements that in an efficient way can be hoisted in place, demand of a minimum of supplementary work, and that is should fullfil various fire resistances.

Hence, there is a need to produce a floor in wood that meets the above mentioned objectives and requirements. This is achieved with a floor pursuant to the present invention as it is defined by the stated features of the claims.

The invention will be further described with reference to the drawings where figure 1 illustrates a side view of a floor, figure 2 illustrates a A-A section of figure 1 and figure 3 illustrates alternative embodiments of a spacing unit.

Reference is made to figures 1 - 3. Unit 1 is built with a camber 6 in the longitudinal direction of the unit so that a close to horizontal surface along floor plan is achieved after the unit 1 is mounted in a building. The unit 1 is thus ready to be covered by the desired surface layer. This camber 6 is obtained without building essential build in pre-tensionings in the applied components, but instead that the lower flange unit 2 is arranged with a camber 6 which is adjusted to the desired range / span and load level. Subsequently spacing units 3 are arranged, which units are between 0.1- 2.0 meters in length, typical 0.3-1.8 meters and preferred between 0.5-1.0 meters, positioned in two or more rows in the longitudinal direction of unit 1. The mutual distances between the rows are between 0.1-1.5 meters, typical 0.1-1 meters and preferred 0.2-0.4 meters. These spacing units 3 may be made of either wood or metal and may have plane parallel contact faces against the two flange plates 2, 4, and may be fixated either by only glue or in combination with mechanical fastening devices such as screws, nails or brackets having premade fastening devices. Within the framework of current cambers for different spans the curvatures of the units 3 constitute only an insignificant rising height, approximate 1 mm throughout the length of the spacing unit. These spacing units may be made in many different ways, in which some typical examples are showed in figures 3 a-d. These alternatives provide solutions that can be appropriate for obtaining good tension transfer, good carrying possibilities for water, outlets and ventilation, and rational manufacturing / production.

The upper flange unit 2 and lower flange unit 3 can be made of a wood material such as solid wood, plywood (Kerto) or something of the sort. However, the flange units may be reinforced to approve the properties of existing flange (2,4), for example by fibreglass or steel in the lower flange (tension side) and integrally casted concrete onto the upper flange (pressure- / compression side).

After the lower flange unit 2 and spacing units 3 are mounted together the upper flange unit 4 is arranged on top and fixed in a corresponding way as for the lower flange unit. After the expiration of any curing time the assembled unit 1 may be taken out of "the camber jig" and passed on in a commissioned phase having components for water, ventilation or similar (not shown) integrated. Due to the fact that the spacing units are arranged with mutual distances it is easy to find transport paths for water, ventilation and electricity.

Furthermore, the edges of the units will be manufactured so that shear forces may be transmitted from one unit and into the other adjacent units after installation in buildings. The reason for this is to render possible implementation of stair, chimney or other desired larger installations. Such transfer of shear forces in sideway direction may for example be made by springs / grooves along the sides 5,7 of the units, by screwable skirtings or similar.

After ended final assembly in the factory the units are temporarily stored before joint transport to the building site.

The applied wood materials are in a suitable way used so that they in the best way possible contribute to the strength and stiffness of the unit, and at the same time contribute to low weight. In short, the unit may be defined as a broad I-profile having two or more spacings arranged between the flanges. Typically, the flanges can be plywood, "thin" units of massive wood or similar. The flanges may also be assembled by two or more materials that constitute a part of different forms for static interaction. The lower flange can for example be reinforced by fibreglass or other fibre materials having high tensile strength and a suitable E-module. For the upper flange one may imagine a combination of materials with high compressive strength. Such cooperation may be beneficial when one therefrom achieves a more cost-efficient carrying capacity / stiffness.

The ability to reduce sound / noise and reduce of step sound / swinging are among the important function properties a floor slab unit must exhibit when applied in different apartments. By increasing the mass in a floor slab the sound penetration is reduced. However, a disadvantage is that such an additional mass contributes to the fact that the bearing structure has to be upsized / up-rated so that the "natural frequency" will not be too low. For example, if one wish to apply glued on concrete to increase the mass it would be natural to build up such units having a bit less tree fibre in the upper flange, but on the other hand some more in the lower flange. By doing this the stiffness may be improved more than the increase of the mass, and so that the requirements of sound and swinging properties can be complied with in a more cost- efficient way.

For this type of units having a relatively open structure both in longitudinal direction and across the possibilities for increasing the mass (reduce the sound penetration) by filling the cavity with sand or other suitable uncompacted materials are good.

By use of massif wood for the lower flange one may obtain a finished panelled ceiling in the underlying floor.