Buildings are known that have foundations and floors which are cast in forms of a solid insulating material which after depositing serve as thermal insulation of the foundation and floor of the respective building.

Such a structure is thus known from Swedish Patent Application No 9500351-3. The form is in this case of cellular plastic and consists of a base and a number of legs extending upwards from the base. The legs are joined to the base by means of e. g. bonding or nailing so that a continuos form for casting both foundation and floor is created. The foundation is joined to the concrete that is behind it by means of rigid bars stuck through the leg on the back of the foundation.

The construction of such a form, which typically will take place on the building site, is difficult and time-consuming and results in a considerable increase in the total construction costs.

The cast foundation is furthermore solid and therefore forms a thermal bridge between a face wall and a back wall which is supported by the foundation.

The object of the invention is to provide a method of the kind mentioned in the opening paragraph that is easier, quicker and less expensive to apply than known so far.

A second object of the invention is to provide a method of the kind mentioned in the opening paragraph that is suitable for making a foundation, that does not form a thermal bridge between a face wall and a back wall on the foundation via the foundation.

A third object of the invention is to provide a method of the kind mentioned in the opening paragraph by means of which the costs for transporting prefabricated form elements to the building site are reduced considerably.

The novel and unique features according to the invention, whereby this is achieved, is the fact that a form is made of the solid insulating material, said form comprising a, seen in cross section, integrated, mainly U-shaped form section having a body corresponding to the bottom of the U, and a first and second leg corresponding to the legs of the U, that a prop is placed on the base sheet on which the building is to stand at a distance, which corresponds to the thickness of the first leg, from the exterior of the future foundation, said prop is by means of e. g. iron spears anchored to the base sheet, that the form section is placed on the base sheet with its first leg abutting the inside of the prop, that the space between the two legs of the form section is filled with casting material, that the casting material is cured to create the wanted foundation or an outer part of this foundation, and that the form section is left as insulation for the foundation or an outer part of this foundation.

Having this design the form sections for the foundation can be made as prefabricated elements which with no further work performed and consequent additional costs immediately can be used on the building site.

The prop keeps the form together during the casting process, thus avoiding having to apply expensive manpower for putting a number of form elements together to one big joint form on the building site.

The upper regions of the two legs of the form section can furthermore be connected to each other by means of toothed plate connectors serving for absorbing the pressure exerted by the concrete in its liquid state on the two legs of the form sections. Such an securing against the legs bending out or breaking due to the pressure from the liquid concrete can quickly and easily be established by means of exactly toothed plate connectors.

The prop which during the casting process kept the form together can be removed after the curing of the casting material so that an upper part of the first leg of the form section or the entire leg can be cut off and placed on the base sheet in front of the foundation in order to form additional insulation in an area outside of this.

The insulation under the floor can consist of one or several layers of insulation boards kept together by toothed plate connectors and placed on the base sheet so that a space is created between the outer edge of these insulation boards and the second leg of the form section. An outer part of the foundation can then be cast in the space between the two legs whereas an inner part can be cast in the space formed between the second leg and the outer edge of the insulation boards.

The foundation formed can advantageously be utilised for a wall consisting of a face wall and a back wall mutually separated by an insulated space. The second leg creates a corresponding space in the foundation which is made in the above way, and is thus contrary to conventional, massive

foundations left without a thermal bridge between the face wall and the back wall via the foundation.

The integrated form section can for reasons of economy advantageously be a standard element which is used for foundations of different kinds. The thickness of the inner part of the foundation can thus be varying. This problem is according to the invention solved by adapting a filling bar of a solid insulating material and letting this bar fill the space between the second leg and the insulation board.

The integrated form sections are typically manufactured as prefabricated elements at a place other than the building site. For example in a factory that manufactures elements of cellular concrete. Due to the design of the form sections, they take up much more space than the volume of the material alone of which the form sections are made. This circumstance means that it in reality will cost a great deal to transport air together with the form sections to the building site.

This cost can be reduced if the form sections are transported in a state in which they by means of the legs are engaging each other two by two.

The invention also relates to a prefabricated block which is designed in such a way that it includes two inherent form sections which by means of the legs are engaging each other in the above-mentioned way. The two form sections are then cut out of the block by means of a heated wire.

The invention furthermore relates to a foundation for carrying a wall consisting of a face wall and a back wall separated by an insulated space. The wall consists of two parts which just as the wall are separated by an insulated space. The insulation in the space of the foundation is a solid insulation of e. g. cellular concrete which is a constituent

part of the form in which the foundation and the adjacent floor are cast. The two foundation parts can mutually be connected by means of e. g. connecting rods extending through the solid insulating material so that the foundation is given the necessary strength and stability even if it is divided into two parts.

Such a foundation advantageously eliminates the conventional thermal bridge via the foundation between a face wall and a back wall.

The invention will be explained in greater detail below, describing only an exemplary embodiment with reference to the drawing, in which Fig. 1 is a fractional view of an insulated concrete foundation and floor of a building, Fig. 2 is a fractional perspective view of a form consisting of a heat insulating material and serving for casting and insulation of the foundation and floor shown in fig. 1, Fig. 3 is a fractional cross-sectional view of the form in fig. 2, Fig. 4 is the form in fig. 3 but cast with concrete and during the cutting off of a part of the form, Fig. 5 is the form in fig. 3 but with the cut-off part of the form placed on the base sheet in front of the form, and Fig. 6 is a perspective view of a rectangular block consisting of a heat insulating material and including two sections of the form in fig. 1.

Fig. 1 is a fractional cross-sectional view of a concrete foundation 1,2 and a concrete floor 3 of a building of which only the wall 4 is shown. The foundation 1,2 and floor 3 are insulated with an insulating material 5 resting on a levelled base sheet 6 which outside the building is under a layer of gravel or sand 7 and a layer of mould 8. In the base sheet 6 is placed a drain 9.

The wall 4 consists of a face wall 10 and a back wall 11. The two wall parts are mutually separated by a space filled with an insulating material 12 for heat insulating the building (not shown).

The concrete foundation is just as the wall 4 divided into two parts, namely the outer part 1 and the inner part 2, that just as the wall are mutually separated by a space filled with an insulating material which however on this spot is a part of the insulating material 5 which is serving for insulating the foundation and floor of the building. The face wall 10 is resting on the outer part 1 of the concrete foundation, whereas the back wall 11 is resting on the inner part 2 of the foundation.

The wall insulation thus continues down into the foundation but normally with a different type of insulation so that the thermal bridge which via massive, conventional foundations is present between a face wall and a back wall advantageously is eliminated.

The two foundation parts 1,2 are anchored to each other by means of connecting rods 13 which e. g. are made of iron and led through the insulation in the space between the two foundation parts. In the floor 3 is furthermore a mesh reinforcement 14 extending into the upper region of the inner

part 2 of the foundation. Reinforcement bars 15 are placed in the lower region of the inner part 2.

The insulation 5 in fig. 1 serves preliminary as form for casting the concrete in, as will be described in detail below with reference to figs. 2-5. The form consists of a solid insulating material which typically can be cellular plastic.

Fig. 2 is a fractional perspective view of a corner of this form 16,17 which essentially consists of a first form section 16 and a second form section 17. The first form section 16 serves together with the second form section 17 as form for casting the foundation 1,2, whereas the second form section 17 forms base for casting of the floor.

The second form section 17 is being built in fig. 2, and as can be seen, it consists in this case of two layers of board 18 which are placed in such a way that the boards in one layer are displaced in relation to the boards in the other layer.

The boards in the two layers are connected by means of toothed plate connectors (not shown).

Fig. 3 is a cross-sectional view in greater detail of a detail of the form 16,17. The first form section 16 is in one piece and is essentially shaped as a U having a body 19, a first leg 20 and a second leg 21 which in continuation of the body 19 is shaped with a longitudinal projection 22. In continuation of this projection is furthermore a filling bar 23 of e. g. the same material as the rest of the form. The filling bar 23 closes off the space between the projection 22 of the first form section and the second form section 17.

Between the two legs 20,21 of the first form section is a first space 24, and between the second leg 21 of the first form section and the second form section 17 is a second space 25. In the lower region of these spaces 24,25, the

reinforcement bars 15 are placed to reinforce the foundation.

The connecting rods 13 are put through the upper region of the second leg 21 of the first form section to connect the two parts 1 and 2 of the foundation solidly to each other.

The two legs 20 and 21 of the first form section 16 are interconnected by toothed plate connectors 26, and the two layers of insulating boards 18 in the second form section 17 are joined by means of toothed plate connectors 27.

Along the exterior of the first form section is furthermore placed a prop 28 of e. g. wood. The prop is firmly anchored in the base sheet by means of iron spears (not shown), and it serves for absorbing the horizontal components of force from the relatively great pressure that the concrete while in liquid state and especially while being vibrated is exerting on the form during the casting process.

In other words, the prop keeps the form together during the casting process whereby the need for having to use expensive manpower for joining the different components of the form is eliminated.

In fig. 4 the concrete is cast into the form, the outer part 1 of the concrete foundation being cast into the space 24 between the legs 20 and 21 and the inner part 2 of the concrete foundation being cast into the space 25 between the first and second form section 16 and 17.

After casting, the concrete is cured after which the prop 28 is removed and the first leg 20 of the first form section 16 is cut off using a knife 29. This process is done immediately after curing so that the covered outer side on the outer foundation part 1 can be overhauled with a float for irregularities, such as small holes, before the surface is too dry.

In fig. 5, the cut-off first leg 20 is laid down in continuation of the body 19 of the first form section 16 in order to form insulation against the base sheet in the area along the exterior of the foundation.

The form that was used for casting of the foundation and the floor now permanently serves as effective heat insulation under the building (not shown).

Finally, filling up with gravel or sand 7 and mould 8 is done as shown in fig. 1, and the face wall 10 and back wall 11 of the wall are built up on the outer part 1 and inner part 2, respectively, of the concrete foundation.

Fig. 6 shows a longitudinal starting block 30 of the same heat insulating material, e. g. cellular plastic, as is used as form for the foundation and floor of the building.

The block has a rectangular cross section and includes two oppositely facing first form sections 16 which by means of the two legs 20 and 21 of the respective form sections are engaging each other firmly.

This is possible because the width of the spaces 24 between the legs 20 and 21 are equal to the width of the second leg 21, and because the extent of the projection 22 from the second leg 21 is equal to the width of the first leg 20.

As can be seen, the length of one of the sides of the rectangle is thereby equal to the sum of twice the thickness of the first leg and twice the thickness of the second leg, whereas the length of the second side of the rectangle is equal to the sum of the thickness of the projection and the length of the first leg.

In fig. 6, the contours of the two form sections 16 are clearly drawn, but in practice the block is cast in one piece in the cellular plastic factory after which the two form sections 16 are cut out of the block by means of a heated wire.

Cellular plastic has a low density, and a lorry which is to transport the form to the building site is therefore not loaded according to weight but according to volume.

Thus if the loading is to take place according to volume, there will necessarily be transported large amounts of air due to the shape of the integrated form sections 16.

If it instead is the rectangular block in fig. 6 made up of two of the integrated form sections 16 firmly engaging each other which is to be transported, the possible transport volume of the lorry is however fully utilised, resulting in great savings in carriage expenses.

In practice, it would be advantageous to be able to manufacture and stock the blocks cut out as a standard product which can be utilised as forms of different structures. The extent of the projections 23 of the cut-out form sections 16 will therefore not always close off the space 25 between the first and second form part in the area at the base sheet 6. A small open space will easily remain.

The remaining space is filled with the filling bar 23 which is adapted on the building site and placed in continuation of the projection.