The present invention relates to a foundation and floor component comprising tvo mutually parallel, preferably rectangular, plates joined by end walls, side walls and preferably parallel and equidistant partition walls which compartmentalize the space bounded by the plates, the end walls and the side walls.

The invention relates also to a base slab composed of a number of adjacently arranged components according to claim 1, and resting on a bed, which starting from the base of the foundation pit comprises a first and a second layer of sand, a layer of gravel separated from the second layer of sand by means of a sheet of non-woven fabric, and on top of all that, a third layer of sand.

For many years, cellerless houses have been erected on a concrete base slab equipped with edge beams, and laid directly on a foundation such as that described above. It is common knowledge that this type of foundation construction gives rise to dampness which leads to attack by mold and rot upon the floors and walls of the house.

The cause of such disadvantages likely is that concrete slab is a relatively good heat conductor, which causes sand at a depth of as far as 1 meter to reach nearly room temperature. This leads in turn to an evaporation of the ground water in the foundation bed and a strong upward vapour pressure, which is hindered by the edge beams from leaking out from the sides. The water vapour condenses against the undermost surface of the concrete slab, and the concrete, which is relatively porous, absorbs the condensed vapour to the point of saturation. The condensate evaporates but recondenses in air pockets and gaps found, for instance, between the floor and walls, thereby causing the above-mentioned problems of dampness.

While it is true that components constructed in the manner initially described are previously known, these are primarily intended for wall and roof components, since the material in the plates is porous and will absorb moisture, and must, for 5 this reason, be provided with a protective surface coating to withstand wind and weather. When used as a foundation component, such previously known components would give rise to the same disadvantages as does a cast concrete slab.

A primary object of the present invention is to achieve a floor and foundation component which does not have the named disadvantages and which moreover is energy conserving, and which can be produced at a low cost. According to the invention, this is achieved in that the plates, end walls, side walls and partition walls are made of a composite material, for instance, a cement-stabilized fibrous material, and in that the compartments are filled with an insulating foam.

λ special characteristic of the invention is that said fibrous material is, for instance, glass fibre, plastic fibre or wood fibre.

Another object of the present invention is to achieve a base slab which, together with its bed, provides a frostproof and moistureproof building foundation. This is achieved thus: an insulating plate, preferably of expanded plastic, is arranged around the base slab, between the named first and second layers of sand so that approximately one-third of the plate extends inward under the edge of the base slab, and with the remaining two-thirds protruding outward, and to connect an insulating plate all around the base slab, said plate extending on ground level outward from the base slab, and preferably covered with cement-based plates.

As is evident by another special characteristic of the invention, the insulting plate is 1 to 1.5 cm wide.

The invention is further explained with references to the appended drawing which in a schematic cross-section shows a base slab resting on a bed according to the present invention.

A foundation and floor component according to the invention comprises two mutually parallel, preferably rectangular, plates 1,2, which are joined to each other, through of a combination of cementing and nailing, by end walls 3, side walls <not shown in the drawing) and partition walls 4). These compartmentalize the space bounded by the plates 1, 2, end walls 3 and side walls.

According to the invention, the material in the plates 1,2, end walls 3, sides and partitions 4, consists of a cement-stabilized fibrous material. Said material can be, for instance, glass fibre, plastic fibre, or wood fibre. The compartments are completely filled with an insulating foam 5. The composite material provides a built-in vapour barrier and has, as does the insulating foam, a low vapour transmission coefficient and a high heat insulation coefficient. The latter item means that the bed zone lying directly under the base slab will be relatively cool and will result in a moisture ratio as low as 60%, a figure considerably lower than that achieved when a cast concrete slab is used.

A building foundation constructed according to the invention, consists of a number of adjacently arranged components joined as described above, and resting on a bed. Said bed comprises, starting from the base of foundation pit 6 and its continuous drainage arrangement 7, a first layer of sand β and on that a second layer of sand 9, which bears a layer of gravel 10 and on that, a third layer of sand 11 upon which the base slab rests. The second layer of sand 9 and the layer of gravel 10 are separated by a sheet of non-woven fabric 12.

According to the invention, there is between the layers of sand 8,9, an insulating plate 13, preferably of expanded plastic, arranged around the base slab so that approximately one-third of plate 13 extends inward under the edge of the base plate and the other two-thirds protrudes outward from said edge covering the drainage arrangement 7. Moreover, arranged around the base plate is an insulating plate 13 extending outward from the base slab on ground level and preferably covered by cement-based plates 15.

The temperature in a zone under the base slab, assuming normal room temperature in a house resting on such slab, will reach about +10' C and is, in any case during the winter, higher than the temperature exterior to the base slab. The purpose of the insulating layers 13 and 14 is to ensure similar temperature conditions also during the summer. Said temperature conditions namely cause moisture, in the form of vapour, to rise from the warmer zone toward the cooler areas exterior to the base slab. The vapour condenses at this point, and the condensate rises and is trapped by the drainage arrangement.

The base slab has a uniform width and homogeneous properties as regards insulating capacity, and creates therefore a state of equilibrium between the vapour transmission and the moisture flow, which have no extreme values along the bottom surface of the base slab.