GB2261252A - Building tie - Google Patents

Abstract

A lateral restraint for securing a wall (2) to joist (3) extending parallel to that wall comprises an elongate rod or tube (1) supporting barbs disposed so that the rod can be driven relatively easily in one direction through a pre-drilled hole the diameter of which is less than the radial extent of the barbs. Thus once the rod or tube is driven through a pre-drilled hole the barbs engage the wall of the hole and prevent the withdrawal of the rod in the opposite direction to that in which it was initially driven into the hole. The restraint may be formed from a rolled strip of steel in which the barbs have been pressed out (Figures 6 - 9). <IMAGE>

Description

LATERAL RESTRAINT The present invention relates to a lateral restraint for providing lateral or rotational support to the wall of a building incorporating timber structural members.

Lateral restraints are used to restrain the walls of buildings against horizontal or rotational displacement. Such restraints may be used in new construction but are also used to improve the structural strength of existing buildings during refurbishment work. The present invention is primarily intended for use in existing buildings where access to the internal building structure is restricted and the installed restraints must not disfigure the external appearance of the building.

In a building with suspended floors, the engagement between the ends of the suspended floor joists and the walls between which they extend is generally sufficient to laterally restrain these walls. Walls which run parallel to the joists are not so restrained however and it is good practice in new buildings and when refurbishing existing buildings to install restraints between joists and adjacent walls to which they run parallel. Where restraints are installed during construction, they are generally in the form of simple steel straps which are screwed to the two joists nearest to a wall and secured in the fabric of the wall. In many existing buildings such lateral restraints are not provided but should be installed during refurbishment. This can only be achieved using conventional straps if internal floor boards can be raised and the external walls can be penetrated.This involves major disruption of the existing structure which is generally undesirable.

This problem has been addressed by providing lateral restraints that can be inserted through holes drilled through the external walls.

In one known system, a hole is drilled through the external wall and through the two nearest adjacent floor joists. A restraint is then assembled from a threaded end piece intended to be screwed into the more distant of the two drilled joists, a stainless steel spacer tube the length of which is slightly less than the spacing between the two drilled joists, and a threaded middle section intended to be screwed into the nearer of the two drilled joists. An outer end piece is secured to the threaded middle section, the outer end piece being intended to be secured for example by epoxy resin in the hole drilled through the wall. The components of the restraint are interconnected by a steel rod screwed into the two threaded sections and extending through the stainless steel tube.The restraint is pushed through the hole drilled in the wall, the restraint is then rotated so that the threaded end piece is screwed through the first joist, the restraint is then pushed further through the hole in the wall until the threaded end piece engages the second joist, and the restraint is then rotated again so that the two threaded sections are screwed into the respective joists.

The known system works well but is not altogether satisfactory.

Firstly, the assembly of components is expensive to manufacture.

Secondly, and of greater significance, its use requires care as the thickness of the wall, the spacing of the joists from the wall, and the spacing between the joists must be accurately determined before the different sections of the restraint can be cut to the appropriate lengths and assembled. Accuracy is particularly important as the installed restraint cannot generally be inspected to ensure that the threaded sections correctly engage the two drilled joists. This problem could be overcome simply by threading all or substantially all of the length of the restraint, but if this approach was adopted installation would be a laborious exercise requiring many turns of the restraint to screw it all of the way through the joist nearest to the external wall into engagement with the second joist.

It is an object of the present invention to obviate or mitigate the problems outlined above.

According to the present invention, there is provided a lateral restraint, comprising a rod supporting barbs arranged along its length, the barbs being disposed so that the rod can be driven relatively easily in one direction through a pre-drilled hole the diameter of which is such that the barbs engage the wall of the hole but is relatively difficult to withdraw in the opposite direction from such a hole through which it has been driven.

The lateral restraint in accordance with the invention depends for its effectiveness upon the realisation that the axial load applied to such a restraint in the event of movement of the external wall is relatively small.

The barbs may be integrally formed so as to project radially from a cylindrical body, or supported for example on collars secured around a cylindrical body. Preferably the barbs are resilient to facilitate the driving of the restraint through pre-drilled holes in the joists. The restraint may carry barbs along its full length but alternative configurations are possible.

In a preferred arrangement, this rod is in the form of a tube, portions of the tube wall being displaced radially outwards to define the barbs. The tube may be formed from a generally rectangular longitudinal strip of resilient material which is rolled about a longitudinally extending axis. The barbs may be defined by pressing out slots along each side of the elongate strip.

Embodiments of the present invention can be fabricated as single units of a predetermined length and the user does not have to make any accurate measurements of the disposition of the wall and the two adjacent joists. The insertion process is also relatively simple.

Embodiments of the present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 illustrates an embodiment of the invention after its insertion into the joists of an existing building; Figure 2 illustrates the end of a restraint of the type shown in Figure 1 in greater detail; Figure 3 illustrates the formation of barbs provided on the embodiment of Figure 1 in greater detail; Figure 4 is a section on Figure 3 along the lines 4-4; Figure 5 is a section through Figure 3 along the lines 5-5; Figure 6 is a plan view of a flat strip the sides of which are slotted and from which a second embodiment of the invention may be formed; Figure 7 is a side view of the second embodiment formed by rolling the strip of Fig. 6 into a tube; and Figures 8 and 9 are sections on lines 8-8 and 9-9 of Fig. 7.

Referring to Figure 1, a restraint 1 is shown after its insertion through a pre-drilled hole in an external wall 2 and through a nearer joist 3 and a farther joist 4. The joists 3 and 4 support floor boards 5. The restraint shown in Figure 1 is inserted firstly by drilling a hole in the external wall 2 the diameter of which is greater than the maximum diameter of any of the barbs on the restraint, secondly drilling holes through the joist 3 and 4 the internal diameter of which is less than the external diameters of the barbs and thirdly driving the restraint through the pre-drilled holes so that the barbs engage the walls of the holes in the joist 3 and 4. A resinous or cementious substance is then injected into the hole through the wall so as to anchor the outer end of the restraint within the wall.Any tendency of the wall 2 to move towards the left in Figure 1 is then prevented by the inter-engagement of the wall 2 and joist 3 and 4 by the restraint 1.

Figures 2 to 5 illustrate the structure of the barbs provided on the restraint on Figure 1 in greater detail. It will be seen that four aligned rows of barbs are provided equally spaced about the circumference of a cylindrical support body. Typically this cylindrical support body will have an outside diameter of 10 mm and the barbs will project therefrom to a radial distance of approximately 5 mm.

The overall length of each barb in the axial direction will be for example 15 mm with the barb tip projecting axially approximately 5 mm in the axial direction. The barbs are arranged in four rows along the length of the restraint with two of the rows being offset axially by approximately 5 mm relative to the other two rows of barbs.

As will be appreciated from Figures 2 to 5, the restraint can be driven relatively easily through a pre-drilled hole in the direction from left to right in Figure 3. In contrast, if a force is applied to withdraw the restraint in the direction from right to left in Figure 3 the barbs will bite into the joist holes within which they are a tight fit, thereby restraining movement of the device relative to the member in which the holes have been pre-drilled.

The restraint may be manufactured from a relatively rigid material or alternatively formed from a resilient material which enables the tips of the barbs to deflect during insertion. Of course the body of the restraint must be substantially inextensible to prevent it stretching significantly under axial load.

It will be appreciated that although in the described embodiment the barbs are formed integrally with a cylindrical main body they could be supported for example on collars mounted on a cylindrical rod. It is merely necessary to dispose the barb portions of the restraint so that they engage the joists through which the restraint is inserted.

It will also be appreciated that alternative arrangements to those described above could be provided. For example, the restraint could be in the form of a tube provided with holes along its sides.

A resinous material could then be pumped into the tube so as to squirt outwards through the holes before setting. Once the resinous material has set, it will hold the tube in position.

It will be appreciated that the barb members need not be pointed formations, but could be elongate or continuous webs of material extending radially, circumferentially and axially in one direction. For example, the barb members may be defined by cupped washer-like structures, or a continuous helical formation, preferably formed from a resilient material.

Thus the invention enables a lateral restraint to be installed to provide a connection between vertical and horizontal members in structures, for example external structural walls and internal floor, ceiling and wall joists. The restraint can be installed with a minimum of disruption and using simple procedures. The restraint can be fabricated from any suitable material, for example metal, rigid plastics, PVC or the like. Anchorage in the external wall using resins is preferred although alternative anchorage systems could be provided, for example a threaded end on the outer tip of the restraint to enable a suitable fixing device to be secured thereto.

Installation requires only simple tools, for example a hammer drill, 16 mm and 20 mm masonry drill bits, a 16 mm pilot drill bit 900 mm long, a hack saw, a flat nosed punch, a measuring tape and resin gun. Once the appropriate height and rough distance between the outer wall surface and the far side of the second joist away from the wall has been ascertained the restraint can be cut to an approximate length and inserted into the pre-drilled holes. Restraints could be inserted every metre along the horizontal run of wall. The restraint can be formed in any suitable material and used in either cavity or solid wall constructions.

A second embodiment of the present invention will now be described with reference to Figs. 6 to 9.

Fig. 6 shows a strip of spring steel which is elongate and generally rectangular and in the two longer sides of which slots 6 have been cut to define members 7 that in the final product form barbs. The strip of Fig. 6 is rolled to form a tube as illustrated in Figs. 7, 8 and 9. The longitudinal edges of the strip define a small gap 8 therebetween which extends along the length of the restraint.

The slots 6 undercut the member 7 so as to define projecting portions which are bent radially outwards to form the lugs.

The embodiment of Figs. 6 to 9 has considerable advantages in that it is cheap and easy to make. The restraint is used in exactly the same manner as in the case of the embodiment of Figs. 1 to 5.

Claims (10)

CLAIMS:

1. A lateral restraint comprising a rod supporting barbs arranged along its length, the barbs being disposed so that the rod can be driven relatively easily in one direction through a pre-drilled hole the diameter of which is such that the barbs engage the wall of the hole but is relatively difficult to withdraw in the opposite direction from such a hole through which it has been driven.

2. A lateral restraint according to claim 1, wherein the barbs are integrally formed so as to project radially from a cylindrical body.

3. A lateral restraint according to claim 1, wherein the barbs are supported on collars secured around a cylindrical body.

4. A lateral restraint according to any preceding claim, wherein the barbs are resilient.

5. A lateral restraint according to any preceding claim, wherein the barbs are disposed to be rotatable about the rod.

6. A lateral restraint according to any preceding claim, wherein the rod is tubular and is provided with holes along its side to enable the escape of material pumped into the rod.

7. A lateral restraint according to claim 1, wherein the rod is in the form of a tube, portions of the tube wall being displaced radially outwards to define the barbs.

8. A lateral restraint according to claim 7, wherein the tube is formed from a generally rectangular longitudinal strip of resilient material which is rolled about a longitudinally extending axis.

9. A lateral restraint according to claim 8, wherein the barbs are defined by pressing out slots along each side of the elongate strip.

10. A lateral restraint substantially as hereinbefore described with reference to Figs. 1 to 5 or Figs. 6 to 9 of the accompanying drawings.