The invention relates to a floor structure.

Floor structures need to meet various design constraints, with regard to carrying capacity, insulation, etc. Besides that, it is of importance that the floor structure itself is as light as possible, and can be cost effectively installed.

An example of a relatively light and cheap floor structure consists of wooden boards, which are fixed on a system of supporting beams. Such a floor however does not have a large carrying capacity.

An example of a known floor structure with a large carrying capacity is a concrete floor. It exists of a system of pre-stressed concrete floor elements, mounted on the system of carrying beams. The floor elements are relatively heavy, and therefore also the carrying beams need to be relatively heavily built.

Especially when the floor is a floor of the lowest building layer of a building, and will be directly in touch with the ground or be separated from the ground through only a crawlspace, moisture and cold are a problem. At the bottom side of the floor structure, the temperature is lower than at the top side. When this temperature difference is to be caught by a structure of wood or concrete, there is a big chance of heat leakage and condensation. This problem especially plays a role if the supporting beams would be made of metal. It is true a metal supporting beam can combine a relatively large carrying capacity with a relatively low weight, yet metal (steel) is a good heat conductor, and it is therefore not obvious to apply metal in the floor structure of a floor on the ground floor.

The present invention provides a floor structure that can on the one hand have a low weight and on the other hand has good properties with regard to strength, insulation and carrying capacity.

These and other aspects, features and advantages of the present invention will be further explained by the following description with reference to the drawings, in which equal reference numbers indicate equal or similar parts, in which the indications "bottom/top", "higher/lower", "left-hand/right-hand" etc. only relate to the orientation shown in the figures, and in which:

figure 1 schematically shows a cross section of a floor structure according to the present invention;

figure 2 illustrates several aspects of a dovetail plate;

figure 3 illustrates a second embodiment of a floor structure according to the present invention. Figure 1 schematically shows a cross section of a floor structure generally indicated with the reference number 1 . The floor structure 1 comprises a system of carrying beams 10 that are mutually substantially in parallel. A characterizing feature of the floor structure according to the present invention is that the carrying beams 10 are made of metal, because then it is possible to make use of carrying beams having a low weight per meter with the carrying beams still having a relatively large carrying capacity. The carrying beams 10 shown in figure 1 have a∑-contour, with a height of 210 mm and a width of 75 mm, but that is not essential.

On the carrying beams 10, a supporting layer 20 is applied of metal dovetail plates 21 , whose longitudinal direction is oriented perpendicular to the longitudinal direction of the carrying beams 10.

Dovetail plates are known per se, and therefore the structure of a dovetail plate will be illustrated only briefly, with reference to figure 2, showing a cross-section of a portion of a dovetail plate. A dovetail plate 21 consists in short of a metal plate with a thickness d, that is folded zigzag wise along mutually parallel folding lines so that an alternation has been formed of plate strips in a configuration of dovetail shaped valleys 31 and mountains 32. Each valley 31 comprises a horizontal plate strip 33 having a width B1 , and two oblique plate strips 34 oriented upwards from the plate strip 33, that enclose an angle a smaller than 90° with the horizontal plate strip 33. Each mountain 32 comprises a horizontal plate strip 35 having a width B2, and two oblique plate strips 34 oriented downwards from the plate strip 35 that enclose an angle a smaller than 90° with the horizontal plate strip 35. The horizontal distance between two neighboring horizontal plate strips 35 of the mountains 32 is indicated with D1 , and the horizontal distance between two neighboring horizontal plate strips 32 of the valleys 31 is indicated with D2. The horizontal plate strips 32 of the valleys 31 sit in a first common plane, and the horizontal plate strips 35 of the mountains 32 sit in a second common plane. The vertical distance H between those two common planes is the building height of the dovetail plate 21 .

A dovetail plate that has proved itself in practice, is a plate marketed under the brand name DUOFOR by the company Duofor B.V. from Dongen, The Netherlands, in which the parameters are as follows:

d: 0,5 mm or more

H: 16 mm

B1 : 33 mm

B2: 38 mm

D1 : 26 mm

D2: 30 mm

The material of this plate is steel. The plate has a weight of around 5.85 kg per m ² . The floor structure 1 further comprises a mortar floor 40 applied on the supporting layer 20. This is a floor that is formed by pouring a hardening mortar on the supporting layer 20, the mortar sinking in the valleys 31 . Traditionally, for a floor to be strong, designers are inclined to make it thick and heavy. The present invention is at least for a part based on the insight that a strong floor can be made by a combination of a lightweight dovetail plate with lightweight mortar with an adjuvant of clay granules. As a mortar, a standard sand-cement mortar, a concrete mortar, or a lightweight mortar can be used. In an especially suited embodiment, a mortar is used consisting of cement with a polystyrene granule as an adjuvant. Such a mortar is strong, lightweight, and has good supplementary insulating properties. At a layer thickness of 20 mm above the supporting layer 20, the combination of mortar floor 40 and supporting layer 20 then has a natural weight of 13 kg/m ² . At a layer thickness of 40 mm, this weight becomes around 20 - 25 kg/m ² . At a center-to-center distance of the carrying beams 10, the total weight of the floor then is around 35 kg/m ² . When a sand-cement mortar is used, the total weight of the floor increases to around 55-80 kg/m ² . When lightweight concrete is used, the total weight of the floor increases to around 80-90 kg/m ² . When regular concrete is used, the total weight of the floor increases to around 100-120 kg/m ² . In all these cases, the total weight is

substantially lower than traditional floors, having a total weight of 180 kg/m ² and more.

If desired, a system of reinforcing bars can be incorporated in the mortar floor 40, though this is not essential, as the dovetail plates also have the function of reinforcement.

If desired, a system of floor heating can be incorporated in the mortar floor 40, based on electrical elements or central heating pipes.

In the alternative embodiment illustrated in figure 1 , also a thermal insulation system is provided for at the bottom-side. This is especially important when the floor structure 1 is applied on the ground floor. The thermal insulation system comprises two components.

A first insulation component is formed by primary insulation bodies 50, that are arranged closely fitting in the intermediate spaces between two neighboring carrying beams 10. In principle, the insulation bodies 50 may be made of an arbitrary, thermally well insulating and lightweight material, and may simply be configured as rectangular blocks. In a preferred embodiment, the insulation bodies 50 are made of EPS foam. Between the insulation bodies 50 and the supporting layer 20 sitting above that, an air cavity 51 of for instance 5 mm or more is left clear.

A second insulation component is formed by secondary insulation bodies 60, each time arranged around the bottom end of a corresponding carrying beam 10, wherein each time, a secondary insulation body 60 joins the two neighboring primary insulation bodies 50. Air below the floor is thus prevented from coming into contact with the metal carrying beams 10, so that transport of cold to the top side of the floor structure is counteracted.

A great advantage of the floor structure according to the present invention is that it can be built in a relatively easy way, relatively quickly and therefore relatively cheaply. First, the carrying beams 10 are mounted. Then, the secondary insulation bodies 60 are mounted on the bottom ends of the carrying beams 10, and the primary insulation bodies 50 are mounted between the carrying beams 10, against the secondary insulation bodies 60. Then, the dovetail plates of the supporting layer are 20 mounted, directly on the supporting beams 10, or possibly with an insulation plate (not shown) in between the dovetail plates and the carrying beams 10. Finally, the mortar 40 is applied, after first having applied floor heating and/or reinforcement, if desired. After hardening of the mortar, the floor structure is ready

Figure 3 schematically illustrates a second embodiment of the floor structure, generally indicated with reference number 301 . Relative to the first embodiment of the floor structure 1 of figure 1 , the most important difference can be seen from the shape of the secondary insulation bodies, that are now indicated with the reference number 360, and that, for the sake of convenience, will be indicated in the following as "insulation profile".

In the first floor structure 1 , the insulation profiles 60 generally have a rectangular outer contour, albeit with rounded corners. The insulation profiles 60 therefore have a top face 61 , 62, side faces 63, and a bottom face 64. The insulation blocks 50 rest on the top face 61 , 62 of the insulation profiles 60.

Relative to the primary insulation profiles 60, the secondary insulation profiles 360 can be described as being provided with an extra wide foot piece 370 at the bottom side. The secondary insulation profile 360 has an inner space 369 within which fits a bottom portion of the carrying beam profile 10. The inner space 369 ends in the top face of the secondary insulation profile 360; the top face parts on both sides of the inner space 369 are indicated with the numbers 361 and 362. Though not essential, the top face parts 361 , 362 in this embodiment sit on mutually the same height. In any case, the depth of the inner space 369 is as big as for the right- hand top face 361 to sit higher than the end curl of the∑-profile 10. Preferably, and as shown, the depth of the inner space 369 is as big as for the left-hand top face 362 to sit at the height of the vertical body of the∑-profile 10.

The second insulation profile 360 has vertical side faces 363, the mutual distance of which is larger than the width of the end curl of the∑-profile 10. Preferably, the mutual distance is more than 2 cm larger than the width of the end curl of the∑-profile 10, more preferably more than 4 cm, so that the insulation thickness at the vertical side faces 363 measures at least 1 cm respectively 2 cm. Preferably, the height of the vertical side faces 363 is larger than 5 cm, more preferably larger than 7 cm, while the insulation blocks 50 are higher than the vertical side faces 363.

At the bottom end of the vertical side faces 363, the second insulation profile 360 has feet 371 extending outwards, forming part of the foot piece 370 mentioned above. The horizontal top face of these feet 371 is indicated as supporting face 365. The supporting faces 365 sit at a level lower than the level of the floor 368 of the inner space 369. Preferably, the level difference measures at least 1 cm, more preferably at least 2 cm.

The foot piece 370 may have a rectangular contour. In the exemplary embodiment shown, the secondary insulation profile 360 has a convex bottom surface 372, having a curvature that may be for instance the curvature of a circle or an ellipse, wherein the end of the convex bottom surface 372 and the end of a supporting face 365 meet each other at an angle of less than 90°. At the lowest point, at the center, the vertical distance to a supporting face 365 is preferably more than 2 cm, more preferably at least 4 cm.

By the proposed floor structure 301 , a better result is reached than with structure 1 . The insulation blocks 50 get to sit in horizontal direction at some distance from the metal carrying beams 10, and their bottom face gets to sit lower than the bottom face of the metal carrying beams 10, by means of which on the one hand the cold is kept further away from the carrying beams 10 and on the other hand the carrying beams 0 are somewhat heated by the heat from above the floor, so that the chance of condensate formation is decreased.

The floor structure proposed by the present invention provides several advantages. In the case of renovation, existing wooden beams can be replaced by the metal supporting beams 10, wherein the carrying beams can be inserted with their head ends in the existing receiving holes in the walls. The exact mutual distance of the beams is not critical, in contrast to the situation with systems having concrete beams and plastic "blocks", that expect a well-defined center-to-center distance of 60 cm.

With existing systems, first, a bottom floor of concrete provided with

reinforcement is poured on the insulating "blocks", and on top of that, the finishing floor is arranged. That means that the insulation layer also has a carrying function during the pouring of the concrete, so that the insulation layer has to be sufficiently thick, solid and strong. With the system according to the present invention, the insulation body 50 is not loaded with the weight of any mortar, so that also relatively weak materials may be used as insulation material.

Furthermore, with existing systems, the total floor will have a rather large thickness. With the distance between the carrying beams remaining the same, the floor structure proposed by the present invention can be thinner and/or be lighter and/or have a large carrying capacity.

Furthermore, it is an advantage that less working cycles are necessary for installing the floor structure. In a preparation phase, ducts for floor heating can be arranged directly on the dovetail plates 21. Next, in a single working cycle, the mortar floor 40 is applied, which is also the finishing floor. This implicates also a substantial timesaving in the fabrication process.

All in all, it is possible for a costsaving of 20% to 25% to be achieved with the floor structure proposed by the present invention.

With regard to a possible floor heating it is of importance that the steel dovetail plates provide an excellent horizontal spreading of heat. Thereby, the floor is sooner at an homogenous temperature, and it is possible to lay the ducts for the floor heating at a larger mutual distance.

It will be clear for a person skilled in the art that the invention is not limited to the exemplary embodiments discussed above, but that various variants and modifications are possible within the scope of protection of the invention as defined in the appended claims. For example, it is possible to use concrete, sand-cement, lightweight concrete, or extremely light thermal mortar for the mortar floor 40.

The reference numbers used in the claims only serve for explanation in understanding the claims in the light of the described exemplary embodiments, and should not in any way be interpreted in a limiting fashion.