GB2141773A

GB2141773A - Replacement wall ties

Info

Publication number: GB2141773A
Application number: GB08316613A
Authority: GB
Inventors: George Samuel Webster
Original assignee: TACKBURN Ltd
Current assignee: TACKBURN Ltd
Priority date: 1983-06-17
Filing date: 1983-06-17
Publication date: 1985-01-03
Also published as: GB8316613D0

Abstract

There is disclosed a wall tie comprising a circular-section rod (10) of stainless steel which at each of its ends has a screw threaded portion (11) which is coated with a layer of plastic material (12), the coatings each providing longitudinally extending equi-angularly spaced ribs (13). Preferably one of the coated ends is of larger diameter than the other. In use the tie is inserted into aligned holes in inner and outer portions of a cavity wall so that the ribs are flattened and form an interference fit with the interior surfaces of the holes. (Figs. 1-3). There is also disclosed a further wall tie formed by two semi-circular elongate shank halves (27, 28) held together by collars (31, 37). At a leading end of the tie a pilot member (29) has a stem (30) received in the shank and an enlarged head (31) outside it. At the rearward end of the shank a length of compressible material (36) is contained in the shank and the shank is splayed thereby. In use the shank is inserted into aligned holes (21, 23) in inner and outer portions (18, 19) of a cavity wall so that as the pilot member reaches the end of one of the holes, further movement of the shank causes the shank halves to splay outwardly over the head (31) and engaging firmly in the inner or outer cavity wall portion. Additionally the compressible material (36) is compressed as the splayed ends of the shank around it are forced together as the rearward end of the shank is received in the other of the aligned holes. (Figs. 5C, 5D). <IMAGE>

Description

SPECIFICATION Wall Tiles This invention relates to wall ties for cavity walls.

It is presently being found that in houses with cavity walls built several decades ago, the wall ties between the inner and outer courses of brick or other material are in many cases no longer effective due to their rusting away. There is thus a need for a replacement wall tie which can easily be fitted to the two existing courses and which will securely engage therewith.

An object of the present invention is to provide such a wall tie, and a method of fixing it to a cavity wall.

According to the present invention there is provided a wall tie comprising a bar having a screw thread at each of its opposite end portions, each screw thread being coated with a layer of plastic material, and each coating having at least one external rib extending longitudinally of the bar.

According to another embodiment of the invention there is provided a wall tie comprising a shank having a tubular leading portion formed from at least two longitudinally extending sections, each of which is part-annular in cross-section, and a pilot member having a relatively wide part at a leading end of a relatively narrower stem, said wide part being wider than the inside of the tubular leading portion of the shank, the pilot member and the shank being assembled together with said relatively wide part of the pilot member forward of the tubular leading portion of the shank, and a rear end of said stem of the pilot member forward of the rear end of the shank, the rear portion of the shank also having a tubular portion formed from at least two longitudinally extending sections each of which is part-annular in cross-section, said rear portion being enlarged relative to the remainder of the shank by compressible material therein.

According to another aspect of the invention there is provided a method of fixing a wall tie to a cavity.

wall, the wall tie comprising a bar having a screw thread at each of its opposite end portions, each screw thread being coated with a layer of plastic material, and each coating having at least one external rib extending longitudinally of the bar, the method comprising forming a hole through one of the inner and outer portions of the cavity wall and forming an aligned hole in an adjacent surface of the other of the inner and outer portions of said cavity wall, and disposing in said holes said opposite coated end portions of said bar respectively as an interference fit between the coatings and the interior surfaces of the holes.

According to a further aspect of the invention there is provided a method of fixing a wall tie to a cavity wall, the wall tie comprising a shank having a tubular leading portion formed from at least two longitudinally extending sections, each of which is part-annular in cross-section, and a pilot member having a relatively wide part at a leading end of a relatively narrower stem, said wide part being wider than the inside of the tubular leading portion of the shank, the pilot member and the shank being assembled together with said relatively wide part of the pilot member forward of the tubular leading portion of the shank, and a rear end of said stem of the pilot member forward of the rear end of the shank, the rear portion of the shank also having a tubular portion formed from at least two longitudinally extending sections each of which is part-annular in cross-section, said rear portion being enlarged relative to the remainder of the shank by compressible material therein, the method comprising forming a hole through one of the inner and outer portions of said cavity wall and forming an aligned hole of a predetermined length in an adjacent surface of the other of the inner and outer portions, driving said wall tie into said holes so that a leading part of said pilot member engages the end of said aligned hole and said longitudinally extending sections at the leading end of the shank are splayed apart around the stationary pilot member and penetrate the material of the inner or outer portion containing said aligned hole, and said longitudinally extending sections at the rear portion of the shank move to compress said compressible material and form an interface fit with the interior of said through hole.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure lisa plan view of a wall tie of the invention, Figure 2 is an enlarged cross-sectional view on the line 2-2 of Figure 1, Figure 3 is an enlarged, fragmentary longitudinal sectional view of part of the wall tie of Figure 1, Figures 4A to 4Eshow stages in a method of fixing the wall tie of Figure 1 to a cavity wall, Figures 5A to 5D show stages in a method of fixing another wall tie of the invention to a cavity wall, where the inner part of the cavity wall is of low density material, and Figure 6 is a view of the rear portion of the wall tie of Figures 5Ato 5D.

Figure 1 shows a wall tie according to a first embodiment of the invention. The tie comprises a circular cross-section stainless-steel rod 10, which is provided at each of its opposite ends with a screw thread 11 (Figure 3). Each threaded portion of the rod has a coating 12 of a plastic material which is stiff, non-flowable, but relatively soft. Synthetic resin plastics material is preferred. The coating 12 has cylindrical external form with equi-angularly spaced longitudinally extending ribs 13. At the end of the tie which is intended to be the leading end, in use, is a reduced diameter portion 14. At the opposite, rear end of the tie, however, the ribs extend to said rear end.

Next to each ribbed portion is a further coated portion 15 which is of cylindrical external form without any ribs. The two coated portions 15 are spaced apart by an uncoated portion 16 of the rod 10. The coated portion 15 towards the leading end of the tie terminates in an annular collar 17, for a purpose to be described hereinafter.

Figures 4A to 4E, illustrate the stages which are carried out to fix the tie to a cavity wall which comprises an inner part 18 and an outer part 19 separated by a cavity denoted at 20. In this example the inner and outer parts are of high density brick or concrete.

Firstly a hole 21 is drilled through the outer part 19 using, for example, a 6.5 mm drill bit 22. This drilling is continued across the cavity and to full depth into the inner part 19 of the cavity wall to form a hole 23 (Figure 4A). A larger 7.0 mm drill bit 24 is then used to clean out and at the same time enlarge the hole in the outer part 19 as shown in Figure 4B. In this example the maximum external diameter of the ribbed leading end of the tie is larger than 6.5 mm and smallerthan 7 mm, whereas the maximum external diameter of the coated rear end is slightly greater than 7.0 mm.

As shown in Figure 4C, the wall tie is then inserted into the hole 21 in the outer part 19, with the reduced diameter portion 14 leading. Initially there is no resistance to the insertion of the tie, since as stated the external diameter of this end portion is less than the diameter of the hole 21. Insertion can thus be made until the position shown in Figure 4D is reached whereupon the ribs 13 on the rear end of the tie engage against the entry to the hole 21 in the outer part 19.

Since as stated the outside diameter of the ribbed end part is somewhat larger than the diameter of the hole 23 and the outside diameter ofthe rear ribbed part is somewhat larger than the diameter of the hole 21, it is not possible merely to push the tie any further to the left once the position shown in Figure 4D has been reached. However if, as shown in Figure 4E, the end of the tie protruding from the outer part 19 is driven to the left, as shown in the Figures, by a hammer 25, the wall tie will become fixed in the cavity wall as shown in Figure 4E, with the leading ribbed part engaging in the hole 23 and the rear ribbed part engaging in the hole 21. As the respective ribbed parts enter their associated holes, the ribs become flattened to a greater or lesser degree dependent upon the clearance between the hole and the cylindrical surface of the coating between the ribs.The ribs in effect become wider and shallower as they engage in the holes. They do not tear away.

By this means a very tight interference fit is obtained. The extent of interference between the ribs of the coating and the interior of the respective holes 21 and 23 is dependent to some extent on the nature of the material into which the wall tie is being fitted.

The length of the tie is less than the depth of the two holes together with the width of the cavity, so that the tie can be driven fully home without the reduced diameter portion 14 engaging the closed end of the hole 23.

No rotation of the tie is desirable or necessary during the process of insertion. Although as described one of the ribbed parts is of a larger outside diameter than the other, it would be possible for these to be equal. However if the two parts are of different diameters, the part which enters the cavity wall first must be the smaller.

The use of the word "plastic" means a material which whilst stiff, is yet soft enough to be distorted, in a controlled manner, in use, as has been described. The use is not restricted to synthetic resin plastics materials, but may include metals, or other materials having the required properties. As described a tight interference fit is thus accomplished and the wall tie thus securely connects the inner and outer parts of the cavity wall.

Any water falling between the parts 18 and 19 in the cavity 20 will tend to be collected at the collar 17, which, when the wall tie is finally fixed in the cavity wall, is disposed substantially at the centre of the cavity 20 and acts as a drip collar. The use of a stainless steel rod 10 is to overcome the problem of rust, and in addition the coating of various parts of this rod also assists to overcome this problem.

Another embodiment of a wall tie of the present invention is disclosed in Figures 5 and 6.

This wall tie is intended to be used where the inner part of the cavity wall is of a material of low density, such as autoclave aerated concrete. Such material has characteristics of limited compressive strength, limited tensile strength, ready compactibility, (usually because of being cellular) to form a cavity for a fixing device, and substantially no recoverability or resilience. These characteristics in combination render many fixing devices, which are good or even excellent in other materials, virtually useless in autoclave aerated concrete or other like low density constructional materials. Similarly the type of wall tie fixing described in Figures 1 to 4 cannot successfully be used with low density material. Therefore an alternative form of wall tie is proposed.

The wall tie of this second embodiment is shown in Figures 5C and 5D. It comprises an elongate stainless-steel shank 26 of generally hollow, circular cross-section. The shank is split longitudinally along its whole length into two longitudinally extending semi-circular sections 27 and 28, which as described are adapted to splay apart, in use, at one end of the shank 26, so as to anchor the shank in the low density part of the cavity wall.

The wall tie further comprises a stainless-steel pilot member 29. The pilot member has an elongated circular section stem 30. Adjacent a leading end of the stem, the stem is formed with an elarged portion 31 formed with a frusto conical surface 32.

From its maximum diameter part, the enlarged portion 31 decreases in diameter by way of a short further frusto conical surface 33 which adjoins a short leading end portion 34 of the stem 30 of the pilot member 29. The maximum diameter of said enlarged portion 31 is greater than the inside diameter of the shank 26 if the two halves of the shank are assembled together to form a circularsection tube. However the diameter of the stem 30 is slightly smaller than the internal diameter of such a tubular shank so that, as shown in Figure 5C, the pilot member 29 can be engaged with the shank 26 with its stem 30 to the one side of the enlarged portion 31 contained within the two shank halves, these being retained together by means of a metal collar 35. The enlarged portion 31 thus projects out of the end of the shank 26 as shown in Figure 5C, with the short leading end portion 34 of the stem ahead of the portion 31. The stem 30 extends in the shank 26 for about a third of its length, as shown schematically in Figure 5D.

At the rear end of the shank 26, the two halves of the shank are slightly splayed apart to accommodate therebetween a length of compressible material 36.

A further collar 37 can be used to assist in securing the material 36 in place. Figure 6 shows a rear end view of the wall tie with the halves of the shank splayed by the material 36.

To fix the wall tie to the cavity wall, the procedure shown in Figures SAto 5D is adopted.

Firstly a drill bit 38 is selected to drill through the outer part 19 of the cavity wall to provide a hole 21 and further to drill a hole 23 in the inner part 18 of the cavity wall so that the depths of the two holes together with the width to the cavity 20 are substantially equal to the length of the wall tie. The reason for this requirement will be apparent as the method steps are hereinafter described.

A drill stop 39 is thus fitted to the drill to ensure accuracy in the depth of the hole drilled in the inner part 18 of the cavity wall. The drilling operation is then performed to provide the holes 21 and 23, these holes being of the same diameters. The wall tie is then inserted into the hole 21 and driven by means of the hammer 25 to the left as shown in Figure 5 so that the shank 26 passes through the hole 21. This driving is continued until the short leading end portion 34 of the pilot member 29 engages against the end of the hole 23 in the inner part 18 of the cavity wall. When this position is reached the rearward end of the wall tie will not have quite completed its entry into the hole 21. In fact, as already mentioned, this end is oversized with relation to the hole by virtue of the ends of the shank being splayed by the compressible material 36.

However if the driving by means of the hammer is now continued, two things occur. The rearward end of the shank is forced into the hole by way of the splayed ends of the shank moving together to compress the material 36 and form a circular end section within the hole 21. In addition this further inward movement ofthe shank causesthetwo halves of the shank at the leading end thereof to be forced against the frusto conical surface 32 of the pilot member 29 thereby causing a splaying of these leading parts of the shank into engagement with the low density material as shown in Figure 5D. This splaying occurs as the pilot member 29 cannot move any further to the left in the hole 23.

The splayed leading ends of the shank 26 thus individually penetrate the low density material forming passages for themselves therein. This provides a very secure anchorage of the tie in the low density material. Likewise the opposite end of the tie is also securely engaged in the brick by virtue of a tight interference fit between the two halves of the shank and the interior surface of the hole 21, the two halves of the shank being in compressive engagement with the material 36.

Thus the wall ties of this invention can be easily fitted to existing cavity walls as replacement wall ties and will engage securely with both parts of the cavity wall whether both parts are of a high density material or whether one is of low density material.

Claims

1. Awall tie comprising a bar having a screw thread at each of its opposite end portions, each screw thread being coated with a layer of plastic material, and each coating having at least one external rib extending longitudinally of the bar.

2. A wall tie as claimed in claim 1, wherein at one end of the bar the coating is reduced in diameter to provide a lead-in portion.

3. Awall tie as claimed in claim 1 or claim 2, wherein an annular drip collar is provided on the bar between said coated end portions.

4. A wall tie as claimed in claim 3, wherein a coated portion of plain cylindrical external form extends from one of said coated end portions and terminates in said drip collar.

5. Awall tie as claimed in claim 4, wherein a coated portion of plain cylindrical external form extends from the other of said coated end portions and terminates at a position spaced from said collar.

6. A wall tie as claimed in any one of claims 1 to 5, wherein each coated end. portion has a plurality of longitudinally extending external ribs equi-angularly spaced therearound.

7. Awall tie as claimed in any one of claims 1 to 6, wherein one of the ribbed coated ends of the tie is of a larger outer diameter than the other end.

8. Awall tie as claimed in any one of claims 1 to 7, wherein the bar is of stainless steel.

9. A method of fixing a wall tie to a cavity wall, the wall tie comprising a bar having a screw thread at each of its opposite end portions, each screw thread being coated with a layer of plastic material, and each coating having at least one external rib extending longitudinally of the bar, the method comprising forming a hole through one of the inner and outer potions of the cavity wall and forming an aligned hole in an adjacent surface of the other of the inner and outer portions of said cavity wall, and disposing in said holes said opposite coated end portions of said bar respectively as an interference fit between the coatings and the interior surfaces of the holes.

10. A method as claimed in claim 9, wherein the total of the combined depths of the holes and the width of the cavity in the cavity wall is at least equal to the length of the wall tie.

11. A method as claimed in claim 9 or claim 10, wherein the diameter of the hole formed through said one of the inner and outer portions is larger than the aligned hole in the other of the inner and outer portions.

12. A method as claimed in claim 11, wherein the tie can be inserted into the through hole until a leading portion of the tie reaches the inner or outer portion containing said aligned hole, and the ribbed coated portion of the tie at the opposite end engages the inner or outer portion containing the through hole, whereupon the tie must thereafter be forced further into the cavity wail with the ribs being flattened to form said interference fit in the holes respectively.

13. A method as claimed in any one of claims 9 to 12, wherein when the tie is fixed to the cavity wall a drip collar disposed on the bar between the coated ends of the tie is positioned in the cavity of the cavity wall.

14. Awall tie comprising a shank having a tubular leading portion formed from at least two longitudinally extending sections, each of which is part-annular in cross-section, and a pilot member having a relatively wide part at a leading end of a relatively narrower stem, said wide part being wider than the inside of the tubular leading portion of the shank, the pilot member and the shank being assembled together with said relatively wide part of the pilot member forward of the tubular leading portion of the shank, and a rear end of said stem of the pilot member forward of the rear end of the shank, the rear portion of the shank also having a tubular portion formed from at least two longitudinally extending sections each of which is part-annular in cross-section, said rear portion being enlarged relative to the remainder of the shank by compressible material therein.

15. A wall tie as claimed in claim 14, wherein said shank is formed of two longitudinally extending semi-circular sections.

16. Awall tie as claimed in claim 15, wherein at least one collar is provided around the two sections to hold them together.

17. Awall tie as claimed in any one of the preceding claims, wherein the pilot member has a frusto-conical surface from the stem to its widest part.

18. A wall tie as claimed in any one of the preceding claims, wherein the pilot member has a frusto-conical surface from its widest part to a narrower leading end portion.

19. Awall tie as claimed in any one ofthe preceding claims wherein said stem is of constant circular cross-section.

20. A method of fixing a wall tie to a cavity wall, the wall tie comprising a shank having a tubular leading portion formed from at least two longitudinally extending sections, each of which is partannular in cross-section, and a pilot member having a relatively wide part at a leading end of a relatively narrower stem, said wide part being wider than the inside of the tubular leading portion of the shank, the pilot member and the shank being assembled together with said relatively wide part of the pilot member forward of the tubular leading portion of the shank, and a rear end of said stem of the pilot memberforward of the rear end of the shank, the rear portion of the shank also having a tubular portion formed from at least two longitudinally extending sections each of which is part-annular in cross-section, said rear portion being enlarged relative to the remainder of the shank by compressible material therein, the method comprising forming a hole through one of the inner and outer portions of said cavity wall and forming an aligned hole of a predetermined length in an adjacent surface of the other of the inner and outer portions, driving said wall tie into said holes so that a leading part of said pilot member engages the end of said aligned hole and said longitudinally extending sections at the leading end of the shank are splayed apart around the stationary pilot member and penetrate the material of the inner or outer portion containing said aligned hole, and said longitudinally extending sections at the rear portion of the shank move to compress said compressible material and form an interface fit with the interior of said through hole.

21. A method as claimed in claim 20, wherein the two holes are of the same size.

22. A method as claimed in claim 21, wherein the holes are produced by drilling, the drill being provided with a drill stop so that the depth of said aligned hole is accurate.

23. A method as claimed in any one of claims 20 to 22, wherein the total combined depth of the holes and the width of the cavity of the cavity wall is substantially equal to the length of the wall tie so that when driven fully into said holes a rear end of the shank is just received in said through hole.

24. A wall tie substantially as hereinbefore described with reference to and as shown in Figures 1, 2, 3, 4, 4D and 4E of the accompanying drawings.

25. A method of fixing a wall tie to a cavity wall substantially as hereinbefore described with reference to and as shown in Figures 4Ato 4E of the accompanying drawings.

26. A wall tie substantially as hereinbefore described with reference to and as shown in Figures 5C, 5D and 6 of the accompanying drawings.

27. A method of fixing a wall tie to a cavity wall substantially as hereinbefore described, with refer enceto, and as shown in Figures 5A to 5D of the accompanying drawings.