Classifications

• • E—FIXED CONSTRUCTIONS
  • E04—BUILDING
  • E04B—GENERAL BUILDING CONSTRUCTIONS; WALLS, e.g. PARTITIONS; ROOFS; FLOORS; CEILINGS; INSULATION OR OTHER PROTECTION OF BUILDINGS
  • E04B7/00—Roofs; Roof construction with regard to insulation
  • E04B7/02—Roofs; Roof construction with regard to insulation with plane sloping surfaces, e.g. saddle roofs
  • E04B7/06—Constructions of roof intersections or hipped ends

Definitions

• the present invention concerns a roof construction including at least three rafters and at least three heads, where each of the at least three rafters is with an inclination relative to the horizontal and is disposed in the roof construction, where each rafter is connected with a head, where this joint between a rafter and a head constitutes a hinge arranged for receiving vertical and horizontal forces, and where each head consists of two end parts and a centre part, where each head end part in the roof construction is connected with another head end part in the roof construction, where this joint between two end parts constitutes a hinge adapted to transmit vertical and horizontal forces between each head end part in the joint.
• Wood is the preferred material for rafter structures as it has optimal carrying capacity in relation to weight, and at the same time is in an attractive price range.
• the roof construction With regard to draining rain water, the roof construction always has an inclination. This entails that vertical loads on the roof from e.g. self-weight and snow cause vertical as well as horizontal forces to be absorbed at the wall head.
• the most well-known method is a horizontal beam between rafters, such as a tie beam or a pole plate.
• this horizontal beam provides a limitation to the headroom inside the house.
• consideration is to be taken to the horizontal beam by the internal covering work, as well as the use of room will be limited by the beam.
• such beams are to be considered when planning the partitionings as interior walls are often placed immediately under the beams in order to simplify the ceiling lining.
• the rafter structure will often require an intermediate support in the form of a supporting inner wall or column.
• Supporting inner walls or columns set limitations on the arrangement of the house which are most frequently unwanted.
• JP 10299089 A Another method of construction is disclosed in JP 10299089 A.
• a polygonal building which is constructed with a central column penetrating a centrally disposed cylindric primary main member upon which the rafters are fastened.
• the rafters are fastened by fittings to underlying heads and side supports. That the construction has a supporting column at the centre sets an unfavourable limitation to the arrangement and use of the house.
• the self-weight of the roof construction will cause lever action on the heads via the rafters, as the heads would tend to turn outwards which in turn causes a change in the slope of the roof.
• Such a settling of the roof construction will be irreparable unless the centre column is re-erected and the cylindric primary main part is lifted up to original position via large jacks.
• the object of the invention is to provide a truss or rafter structure which is particularly suited for buildings in which is desired a total freedom of partitioning and the possibility of ceiling up to the ridge where hence there are no internal supporting walls or columns.
• this object is achieved by a roof construction of the kind mentioned in the introduction which is peculiar in that the joint between a rafter and a head is disposed entirely or partially in a cross-section of the rafter, for example in a bevelled recess in the rafter at the lower end of the rafter.
• the heads By in this way connecting all heads into a head construction and let the rafters be enclosed by all the heads in whole or part of the cross-section of the rafters, the heads will cooperate in absorbing horizontal components of the forces on the roof construction. In statics, this corresponds somehow to the way in which a hoops encloses a number of staves in a wood barrel.
• the hoop absorbs the horizontal components of forces from e.g. liquid pressure from a viscous content in the barrel. The force from the liquid pressure acts on the staves, which hereby are pressed evenly out against the hoop which in this way will act like a tie which is prestressed.
• the prestressing provides that relatively small local forces acting opposite to the horizontal components are immediately absorbed in the form of relieving the hoop material.
• the self-weight of the roof construction according to the invention will entail that the rafters will stem out against the heads, since the joint between a rafter and a head is disposed entirely or partly in a cross-section of the rafter.
• the cross- section may assume many shapes and may thus be bevelled in various ways and be disposed as a recess at different points on the rafter. Most often, however, it will be the rafter end which is designed with bevelled recess corresponding to the outer dimension of the head.
• each rafter is a hip rafter, where the roof surfaces adjoining the hip rafter are disposed in separate planes.
• Each rafter may, as mentioned, be a hip rafter, where the hip rafter moreover may be connected with the head at the end of the head.
• heads in the roof construction will be straight. Thereby is achieved that heads may be produced from standard timber, providing a cheaper and less time-consuming production. At the same time, mounting will be simplified, shortening the time of mounting due to the fact that checking whether the head is positioned correctly in relation to the rest of the construction is easier to perform with current tools like bubble level and inch rule.
• heads in the roof construction may form an equilateral polygon.
• Heads in the roof construction may advantageously form an equilateral polygon with more than four sides, preferably with eight sides.
• Houses utilising a roof construction indicating this multilateral polygonal shape at the disposition of the encircling outer walls will entail that the housing is provided a minimal outer wall area compared to the volume of the inner rooms of the house.
• a minimal outer wall area compared with the volume all things considered there will be a smaller area where heat exchange with the surroundings will occur, meaning less energy consumption for heating the room when it is colder outside than desired inside.
• Rafters and/or heads can be made of wood, preferably of laminated wood, wherein the greater part of the layers of laminated wood have a fibre direction in parallel with the longitudinal direction.
• wood for the supporting structure, the drawbacks associated with metal trusses, e.g. steel trusses, are avoided. Since supporting members made of steel will require fire insulation in order to counteract rapid collapse of the steel truss in case of fire, the increased cost of purchasing and mounting fire insulation is avoided. As mentioned before, wood is a material that has optimal carrying capacity in relation to weight, and at the same time wood is in an attractive price range.
• wood has the advantage that it is more insulating than a metal truss, why possible thermal bridges in the roof construction are avoided. Moreover, it is possible to finish wood with tool types that are commonly accessible on a construction site, and lastly wood is a recyclable product which, if not otherwise, can be used for heating after use in the building construction.
• laminated wood provides the advantage that in the production of laminated wood, weak spots such as knots and pockets of resin are cut off the wood used for laminated wood.
• high-strength laminated wood the wood used for producing high- strength laminated wood has furthermore been sorted and oriented such that the fibre direction of the laminated wood layers lies in parallel with the longitudinal direction. A few layers may, however, be with the fibre direction transversely to the longitudinal direction.
• This type of high-strength laminated wood goes i.a. under the trade name Kerto-S and Kerto-Q, and compared to traditional construction wood it is distinguished by being stronger, why the rafter/head dimensions can be narrower and thereby lighter.
• visible rafters in the room wooden rafters provide an attractive aesthetic quality to the room by their natural surface.
• Rafters and/or heads may also be made of composite material.
• the roof construction is assembled in a uniform and well-defined way, so as to provide for the transmission of force between rafters and heads being effected in the way supposed by the static calculation forming the basis of the construction. It is possible with a good quality control of the production of the fitting while at the same time an optimisation of the production provides an attractive price to the product. By a good and quality controlled fitting for head end joints, which is furthermore protected against corrosion, there is less risk of failure of the construction.
• the joining at the top of the roof construction may also occur in a safe way by using a prefabricated fitting for this purpose.
• a prefabricated fitting for this purpose.
• joints between head ends can be made with fittings, where the fitting consists of two parts, where respective parts are mounted at each their rafter end and subsequently assembled and clamped together, constituting a hinge connection.
• the fitting can be mounted on the head while the head is situated at a suitable working level. This provides a more secure fastening of the fitting than if it should occur from a ladder. As the rafters are most often to be mounted by means of a crane for reducing the mounting time on the construction site, this assembly method will furthermore contribute to reducing the amount of mounting work with a cost-incurring crane.
• the fitting consists of two parts, these may be clamped together after placing rafters and heads in the construction. This may be an advantage if it is desired to finely adjust the rafter slope, for example. Since all heads are interconnected and enclose the rafters in that the joint between a rafter and a head is provided entirely or partly in a cross-section of the rafter, a clamping of the joint between two heads will entail a smaller periphery of the assembled head construction and lead to an elevation of the top point of the rafter, thereby providing a steeper rafter slope. This is particularly suitable by juxtaposing several roof construction according to the invention, where it would appear aesthetically wrong if the roof slopes varied slightly on the juxtaposed construction.
• Fig. 1 shows an octagonal roof construction in a schematic line drawing
• Fig. 2 is a plan view of a head-rafter joint
• Fig. 3 is an elevation of a head-rafter joint
• Fig. 4 is a sectional view showing a section of a head-rafter joint.
• Fig. 1 appears an octagonal roof construction 1 where all rafters 2 are hip rafters. The rafters 2 are joined by a hinge at the top 3 of the roof construction 1.
• the roof construction 1 consists of eight rafters 2 and eight heads 4. All rafters 2 is mounted at an angle 5 in relation to horizontal. Each rafter 2 is connected with a head 4 by a hinge joint 6 between rafter 2 and head 4. Each head 4 consists of two head ends 7 and a centre part 8.
• the self- weight of the rafters 2 will cause the heads 4 to be pre-stressed by means of the tensile forces resulting from the force by the self-weight of the rafters 2.
• Fig. 2 shows a plan view of a possible embodiment of a head-rafter joint 9.
• Heads 4 with head ends 7 are shown hatched, as the heads 4 are both constituted by straight cut laminated wood.
• the head end 7 is placed in a U-profiled fitting 10 which is bevelled and made with an end closure 11 which is mounted by bolt assemblies 12 in the end closure 11 at the opposing U-profile fitting 10.
• the U-profile fittings 10 are fastened to the hip rafter 2 by mounting screws 13.
• a force distribution plate 14 is mounted where the end 7 of the head is mounted in the U-profile fitting 10.
• U-profile fitting 10 and head end 7 and the force distribution plate 14 are joined by a number of through- going bolts 15.
• the heads 4 are disposed over an outer wall structure 16.
• Fig. 3 is a elevation of the same head-rafter joint 9 as the one shown in Fig. 2. It appears here that the U-profile fitting 10, the head end 7 and the force distribution plate 14 are joined by twelve through-going bolts 15. The U-profile fittings 10 are fastened to the hip rafter 2 by three mounting screws 13 fitted in elongated holes 17 for horizontal adjustment. The joint between the two end closures 11 in the U-profile fittings 10 is shown with a spacing 18 for accommodating thermal and/or moisture related elongation/reduction of the heads 4 and at the same time for tensioning the head-rafter structure.
• Fig. 4 is shown how the hip rafter 2 at its lower end 19 towards its joint 6 with the head 4 is provided with a cutout 20, where the horizontal part 21 of the cutout 20 serves as base for the head joint 9, and wherein the vertical part 22 of the cutout 20 is bevelled.

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• Engineering & Computer Science (AREA)
• Architecture (AREA)
• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Civil Engineering (AREA)
• Structural Engineering (AREA)
• Joining Of Building Structures In Genera (AREA)
• Rod-Shaped Construction Members (AREA)

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• 2007
  • 2007-07-10 DK DK200701015A patent/DK176686B1/da not_active IP Right Cessation
• 2008
  • 2008-07-08 WO PCT/DK2008/000258 patent/WO2009006896A2/en active Application Filing
  • 2008-07-08 EP EP08758267A patent/EP2209953A1/de not_active Withdrawn

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