Classifications

• • E—FIXED CONSTRUCTIONS
  • E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
  • E02D—FOUNDATIONS; EXCAVATIONS; EMBANKMENTS; UNDERGROUND OR UNDERWATER STRUCTURES
  • E02D27/00—Foundations as substructures
  • E02D27/01—Flat foundations
  • E02D27/02—Flat foundations without substantial excavation
• • E—FIXED CONSTRUCTIONS
  • E04—BUILDING
  • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
  • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
  • E04B1/0007—Base structures; Cellars
• • E—FIXED CONSTRUCTIONS
  • E04—BUILDING
  • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
  • E04B1/00—Constructions in general; Structures which are not restricted either to walls, e.g. partitions, or floors or ceilings or roofs
  • E04B1/62—Insulation or other protection; Elements or use of specified material therefor
  • E04B1/74—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls
  • E04B1/76—Heat, sound or noise insulation, absorption, or reflection; Other building methods affording favourable thermal or acoustical conditions, e.g. accumulating of heat within walls specifically with respect to heat only
  • E04B2001/7683—Fibrous blankets or panels characterised by the orientation of the fibres

Definitions

• the present invention relates to a method for insulating the foun- dation of a building, where a load distribution layer is made on top of an insulating layer, both layers covering the intended floor area of the building substantially entirely, and to an insulated foundation.
• the load distribution layer also known as the ground slab, is usually a concrete layer cast in-situ and spanning continuously from one side of the foundation to the other.
• the insulating layer is intended to prevent thermal loss from the floor.
• Mineral wool products in the form of high density batts has been used for this purpose, but their weight and the fact that three or more lay- ers of batts have to be laid to achieved the desired insulation has led to this method being almost entirely abandoned. Other more light weight mineral wool products have had to be disregarded due to insufficient load- bearing capacities and walkability.
• the formation of the insu- lating layer comprises the steps of laying a plurality of lamella elements made from mineral wool close to one another with the primary orientation of the mineral wool fibres of the lamella elements being approximately vertical, and providing one or more cover element(s) on top of the lamella elements to cover an upper surface of the lamella elements substantially entirely.
• the object of the invention is further achieved with a foundation where the insulating layer comprises a plurality of lamella elements made from mineral wool lying closely adjacent to one another with the primary orientation of the mineral wool fibres of the lamella elements approximately vertical, and one or more cover elements on top of the lamella elements, covering them substantially entirely.
• the vertical orientation of the fibres in the lamella elements means that the load-bearing capacity is relatively high in comparison to traditional mineral wool batts or mats, where fibres are oriented primar- ily in the plane of the batt or mat. This means that the weight of the insulation needed for insulating a certain area is lower than with traditional mineral wool products.
• the compressive strength of low density mineral wool insulation with fibers orientated substantially vertical to the major surface of the insulation is improved compared to fibers orientated hori- zontally, due to the fibers having a vertical orientation are better at carrying loads.
• the lamella elements undergo only very limited deformation.
• the cover element(s) improves the walk- ability of the insulating layer, which is advantageous during construction, allowing the cover elements to serve as a bearing surface and be walked on, when the load distribution layer is made.
• cover elements are that they cover at least some of the joints between the lamella elements. This keeps the lamella elements from moving away from each other, both by providing friction on the upper surface of the lamella elements.
• a still further advantage of the cover elements is that concrete is prevented from penetrating into the joints when making the load dis- tribution layer. Such movement could result in gaps between the lamella elements and thus in the formation of thermal bridges.
• thermal bridge is intended to cover a ny structure resulting in an undesired thermal loss, i.e. both a heat loss when the ground is colder than the inside of the building and an unde- sired heating when the temperature of the ground is higher than the desired indoor temperature.
• the strength of the fibres in the direction parallel to their length axis of course prerequisites that the fibres do not deflect. If the lamella elements are not laid very close to each other or the plinth, both along their sides and ends, this may be a problem and the result will be that the lamella element becomes deformed. This will not only result in a loss of load-bearing capacity but will also influence the insulating properties. Laying the lamella elements in a bond pattern may lessen this problem as the joints are then no longer all on-line, and a deformation at one joint will therefore not result in increased loads on the neighbouring joints.
• the cover elements can be laid so that at least some of the joints between them are not directly above parallel joints between lamella elements.
• the cover element may in principle be made from any material suited for being in contact with the load distribution layer, which is typically, but not necessarily, made from concrete cast in-situ. Mineral wool being relatively inert fulfils this requirement and has the added advantage that the cover element will then contribute considerably to the insulating properties of the total structure.
• Alternatives could be precast lightweight concrete elements, boards of wooden materials such as plywood, plaster boards, steel or iron plates or the like.
• the lamella elements and/or the cover elements are made of mineral wool, which is both walkable and relatively insensitive to the variations in temperature and humidity occurring in foundations.
• the mineral wool has a density of more than 55 kg/m 3 to ensure a good load-bearing capacity.
• cover elements must carry the load distribution layer and transfer it to the lamella elements, it is advantageous to use a high density mineral wool board having a density of 130-230 kg/m 3 and a thickness of 20-40 mm.
• the cover elements can be made with a relatively stiff upper part intended to face upwards in the mounted state and a softer lower part intended to face the lamella elements.
• the cover elements are made of mineral wool, the combination of an upper part having a density of approximately 135-150 kg/m 3 and a thickness of approximately 10-20 mm and a lower part having a density of approxi- mately 95 kg/m 3 and a thickness of approximately 30-40 mm and dimensions of approximately 1200 x 2000 mm has proven to function well. This results in a total weight of each cover element of less that 10 kg, which is acceptable under the working environment legislation of most countries.
• the size and weight of the lamella elements should be kept so that they can be handled by a single person.
• lamella elements being 200-300 mm wide, 200-500 mm high and 2000 mm long and thereby covering U-values between 0,15 and 0,08, have proven to be fitting, the height being the dimension which is substantially parallel to the primary direction of the fibres.
• the lamella elements are simply laid out closely side-by-side, the last one of a row possibly being cut to size or alterna- tively, but less preferred, compressed so that the floor area of the foundation is covered entirely.
• the cover elements are then arranged on top, possibly with a similar size adaptation, the friction between the materials of the different elements is usually sufficient to provide a stable insulating layer. It is, however, also possible to secure the lamella elements and/or cover elements either to other parts of the foundation or to each other, which may be achieved by providing at least some of them with a surface coating in the form of an adhesive.
• cover elements could be provided with a primer for preparing the surface for contact with concrete or the like.
• insulating material of the lamella and/or the cover elements may be employed for increasing the durability of the insulating material of the lamella and/or the cover elements.
• the lamella elements are arranged directly on a capillary barrier layer as explained above to prevent a rise of soil moisture, thus keeping the insulation dry.
• the insulating layer will be laid directly on the ground and in such cases a surface coating may be relevant, but it is of course also possible to provide for example a sheet of a plastic material underneath the insulating layer.
• cover elements When making the load distribution layer from concrete cast in- situ, some or all of the cover elements may be provided with spacers for concrete reinforcement, which may for example be in the form of a mesh of steel wires. Said spacers can be either integrated in the cover elements or applied to them in-situ, either before or after installation. When concrete is then cast on top of the cover elements, the spacers and reinforcement will become embedded.
• a building with a foundation according to the invention may be provided with a ventilation system comprising a duct extending from the insulating layer to the exterior of the building and a ventilator adapted for pulling air up through the duct away from the insulating layer.
• the method and foundation described herein is based on the use of a single layer of lamella elements (independent of the required thickness of insulation), since this will be sufficient to achieve a good insulation, which fulfils the building regulations of most countries. It is, however, to be understood that it is also possible to lay out two or more layers of lamella elements on top of each other. In that case the lamella elements in each layer should preferably be laid out with their length axis direction being perpendicular to the direction of the length axes of the lamella elements in the layer below.
• Fig. 1 is a cross sectional view of a first embodiment of a foundation according to the invention
• Fig. 2 is a perspective sketch of the foundation in Fig. 1 during construction, the line I-I indicating the cross-section in Fig. 1, and
• Fig. 3 is a cross sectional sketch of building with foundation according to the invention.
• a foundation according to the invention including a load distribution layer 1 and an insulating layer 2 composed of lamella elements 3 with cover elements 4 on top is shown in Fig. 1.
• the lamella elements are laid out directly onto a capillary barrier 5 isolating them from the ground 6.
• a plinth 7 intended for supporting a load bearing structure (not shown) of for example a building defines the outer boundaries of the foundation.
• the plinth 7 is composed of a foun- dation block 71 made from concrete and two layers 72 of insulated foundation blocks made from aircrete with a filling of a foamed plastic serving as insulation.
• the foundation may include further features such as capillary barriers on the outer side of the plinth 7, but as such features will be readily imaginable to the skilled person and are not of consequence for the present invention, they will not be described here.
• the dimensions and construction of the features shown may vary depending for example of the loads to be carried by the foundation, the climate zone, soil conditions, local building traditions etc. without departing from the scope of the invention.
• the load distribution layer 1 is made from concrete cast in-situ and is thus without joints, except for where it meets the plinth 7. This way of making the load distribution layer is well tested and works well under virtually all conditions, but alternatives such as precast concrete slabs, boards of wooden materials or composites may also be used. Materials having large coefficient of thermal expansion or which display large volume changes in response to changes in humidity should, however, be used with care.
• the lamella elements 3 and cover elements 4 are here made from stone wool.
• the primary orientation of the fibres are vertical, while the cover elements are walkable stone wool boards with a relative high density at least at the upper side facing the load distribution layer. Details with regards to these materials will be de- scribed later.
• each cover element 4 has a width WC, which is considerable larger the width WL of a lamella element 3, here approximately seven times larger, and a length CL which is somewhat larger then the length LL of a lamella element, here I V2 times larger.
• the height of the cover elements HC is considerable smaller than the height of lamella elements HL, here constituting approximately 1/3 as may be seen in Fig. 1.
• the lamella elements 3 and cover elements 4 are laid in a simple side-by-side and end-to-end pattern as here, this means that joints between the cover elements are present only over every seventh joint between lamella elements at the length sides and every third joint between end sides of the lamella elements.
• Other size-ratios between the lamella elements 3 and cover elements 4 will result in different patterns, where coinciding joints are more or less frequent.
• the cover elements may be given a different shape or arranged in a different orientation so that the joints between them are not parallel to the joints between lamella elements, but this require a more complex production and/or laying technique and will therefore rarely be expedient.
• lamella elements side-by-side and end-to-end as shown in Fig. 2 is relatively easy.
• the workmen can simply start from the corner 73, where the two sides of the plinth 7 meet and then lay the lamella elements close against each other until the entire area is covered.
• Some lamella elements and/or cover elements may, however, have to be cut to size to fit the area of the foundation as illustrated by the lamella elements in the row to the left in Fig. 2, which are only half as long as the others.
• the materials used for insulating area of approximately 10 m 2 corresponds to what can be loaded onto a standard pallet.
• the lamella elements 3 a re made from stone wool, where the primary orientation of the fibres is vertical.
• loads from the load distribution layer 1 affect the material substantially in parallel to the length axis of the fibres, where the strength is high, and that the stone wool with a relatively low density can thus be used.
• the stone wool is characterized by a low deformation in compression in this direction, a factor which might otherwise potentially reduce the insulating properties.
• cover elements 4 are made from stone wool, but other materials may be employed as long as they are suited for contact with both the lamella elements and the load distribution layer, or at least provided with a surface layer that is.
• the cover elements are stone wool boards, where the orientation of the fibres is substantially in the plane of the layer of cover elements. This allows them to contribute to the load distribution and decrease the risk of cement sludge penetrating into the material.
• the cover elements are preferably of a somewhat higher density than the low density lamella elements and typically also board shape as opposed to the preferred rod-shape of the lamella elements. A density of the cover element of 130-230 kg/m 3 as opposed to 90-220 kg/m 3 for the lamella elements is preferred.
• the cover elements may be boards with an upper part having a density, which is higher than the density of a lower part arranged against the lamella elements.
• the exact densities of these two parts may vary, but it is preferred that the upper part has a density of 90-180 kg/m 3 , prefera- bly 110-160 kg/m 3 , more preferred approximately 135 kg/m 3 , and that said lower part has a density of 65-125 kg/m 3 , preferably 80-110 kg/m 3 , more preferred approximately 95 kg/m 3 .
• the dimensions of the upper and lower parts may also vary depending on demands, but it is preferred that the upper part has a thickness of 3-50 mm, preferably 5-30 mm, more preferred approximately 10-20 mm, and that the lower part has a thickness of 10-60 mm, preferably 20-50 mm, more preferred approximately 30-40 mm.
• a steel wire mesh 8 is laid out on top of the cover elements 4.
• This mesh is intended to serve as reinforcement in a concrete layer, which is to be cast on top of the cover elements to serve as the load distribution layer.
• the reinforcement mesh is provided with spacers (not visible) on its underside to keep it at a distance above the cover elements so that the mesh will become completely embedded in the concrete.
• Spacers are preferably made from a material having a low thermal conductivity, such as plastic or concrete and may be integrated in the cover elements. They may be simple feet inserted between the mesh and the cover elements, resting on top of these, or they may be made to penetrate into the material of the cover elements, which will contribute to keeping them in place when the fresh concrete is poured over them.
• gasses and moisture rising from the ground may tend to build up in the insulating layer. This may not be a problem for the insulating layer itself, but such gasses and moisture should be prevented from reaching the load distribution layer 3 and potentially penetrate into a building on the foundation.
• openings or channels are formed in the insulating material to allow such gasses and moisture to be removed.
• air or gas may drawn directly through the insulating layer 2 thanks to the relatively open structure of mineral wool and the relatively low density of the lamella elements.
• Removal of gasses and moisture is preferably achieved by providing an underpressure in the insulating layer 2.
• This may be done with a system as illustrated in Fig. 3, showing a cross-section of a building 9.
• the gas removal system here consists of a duct 91 extending from the insulating layer 2 to the roof 92 of the building and a ventilator 93 adapted for pulling air or gas up through the duct.
• the ventilator 93 When the ventilator 93 is running, air will be pulled from the insulating layer 2 of the founda- tion and ejected to the exterior of the building above the roof 92, thus creating an underpressure in the insulating layer.
• the ventilator need not run constantly but can be started at regular intervals and/or be connected to a humidity or gas sensor in the insulating layer.
• duct 91 does not need to penetrate the roof 92 of the building but may instead end at an exterior wall 94 or even at the exterior side 95 of the foundation.
• a single duct 91 and ventilator 93 may be sufficient, but that it is of course also possible to provide two or more ducts and/or ventilators, just as several ducts may be joined and connected to a single exhaust.
• the number and capacity of ducts and ventilators used in a particular building depends amongst others on its size, its use, the surrounding climate and soil conditions.
• two layers of cover elements may be provided on top of each without coinciding joints to prevent concrete from penetrating the insulating layer.
• Another example is the use of plastic sheets or the like at different levels in the foundation serving as moisture barriers, vapour barriers, concrete shuttering, load distributor or the like.

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• Engineering & Computer Science (AREA)
• Architecture (AREA)
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• Structural Engineering (AREA)
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• Physics & Mathematics (AREA)
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• General Engineering & Computer Science (AREA)
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• 2011
  • 2011-07-07 EP EP11173100A patent/EP2543771A1/de not_active Withdrawn
• 2012
  • 2012-06-29 WO PCT/DK2012/050232 patent/WO2013004237A1/en active Application Filing
  • 2012-06-29 EP EP12732517.3A patent/EP2729625B1/de active Active
  • 2012-06-29 DK DK12732517.3T patent/DK2729625T3/da active

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