GB1598785A

GB1598785A - Gauging cracks in buildings

Info

Publication number: GB1598785A
Application number: GB4647876A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1977-11-07
Filing date: 1977-11-07
Publication date: 1981-09-23

Description

(54) GAUGING CRACKS IN BUILDINGS (71) We, ROGER WILLIAM JOHNSON, of 61, Down Road, Portishead, Avon, formerly of 7 Swallow Gardens, Weston-super Mare, Avon, and PATRICK VERNON FINN COSGROVE, of 63 Southbrook Road, Havant, Hampshire, PO9 lRL, formerly of 38 St.

Peters Road, Portishead, Avon, both British Subjects, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to gauges for measuring cracks in buildings, and more particularly to gauges by means of which the extent by which a crack opens or closes over a period of time may be measured. It also relates to a method for measuring such cracks.

According to one aspect of the present invention there is provided a method for the measurement of cracks in buildings, comprising securing two plates to the building, at respective securing points each on a respective side of the crack to be measured, so that the plates are in overlapping relationship and slidable over each other as the crack opens or closes, each plate being provided with markings which more rigidly with the side of the crack on which the corresponding plate is secured, by means of which the movement of one plate with respect to the other can be directly estimated in terms of the movement of the markings with respect to each other, and subsequently monitoring the movement of the markings with respect to each other to provide a direct indication of the movement of the crack.

According to a second aspect of the present invention there is provided a gauge for the measurement of cracks in buildings, comprising two plates each having a portion provided with markings, there being provided as an integral part of at least a first one of said plates a securing portion which projects with respect to the portion of that plate which has markings, whereby the plates can be secured one on each side of a crack to be measured, the securing portion of the first plate offsetting the portion thereof which has markings so as to be in slidable overlapping relationship with the portion of the other plate which has markings, whereby the movement of the markings with respect to each other provides a direct indication of the movement of the crack.

In order that the invention may be more clearly understood, two embodiments will now be described by way of example, with reference to the accompanying drawings, wherein: Figs. 1 and 2 are views of a front plate and a back plate of a gauge respectively, Fig. 3 shows the back plate of Fig. 2 in plan, Fig. 4 is a view of an alternative front plate, and Fig. 5 is a cross-section on the line V-V through either front plate together with the back plate.

Referring firstly to Figs. 1 to 3; the front plate 10 and the back plate 12 are both made from transparent acrylic plastics material and are generally rectangular. Each plate 10, 12 has an end portion 14 of double the thickness of the rest of the plate. Each end portion 14 has two holes at 16 for accepting screws for securing the plate to the building.

Each plate also has a pair of opposing recesses 18 in its longer sides.

The front plate 10 is provided with two black hairline indicator marks 20 which cross each other at right-angles. The back plate has a scale region 22 in which black scale calibrations are provided on a white background coated onto the plate 12. Scale graduations extend in all directions from a central origin 23 of the scale region 22.

In use, the gauge is supplied with the front plate laid over the back plate, the recesses 18 of the two plates coinciding. The end portions 14 of the plates are at opposing ends of the assembly thus formed, the increased thickness thereof being arranged such that the entire assembly forms a plate which is nowhere more than twice the thickness of the individual front and back plates. The front and back plates are attached together by wrapping tape round the assembly, the tape being located in the recesses 18. Adhesive masking tape could be used, but a transparent adhesive tape such as "Sellotape" (registered Trade Mark) enables the scale markings to be seen. The point at which the hairlines 20 on the front plate 10 cross overlies the central origin 23 of the scale region 22.

Preferably the hairlines 20 and scale region 22 are formed on those faces of the front plate 10 and back plate 12 which touch each other, in order to reduce parallax error.

The assembly thus formed is placed over a crack, for example in a wall of a building, which it is described to monitor. One end region 14 is placed on one side of the crack, while the other end region 14 is placed on the other side of the crack. The assembly is then secured in place on the wall straddling the crack by means of screws through the holes 16. The adhesive tape can then be removed, or alternatively it can be left in place as it will deteriorate in time and in any case will not be as strong as the securing provided by the screws through the holes 16. In time, as the crack in the wall of a building opens or closes, the positions of the hairlines 20 over the scale region 22 will change because one plate is secured to one side of the crack while the other is secured to the other side of the crack. The movement can thus be monitored at intervals.Because the scale graduations extend in all directions from the origin 23, relative movement of either side of the crack can be measured whatever the direction of movement.

Fig. 4 shows an alternative form of front plate 24, for use where the crack to be monitored is near a corner of the building.

The front plate 24 is intended for use with the back plate 12 seen in Figs. 2 and 3, and is generally similar to the front plate 10 of Fig.

1 except that instcad of a thickended end portion 14 of the plate it has an upstanding securing portion 26 at one end of the plate and at right-angles thereto. This securing portion 26 is provided with the screw holes. It is used in exactly the same manner as the plate 10, except that the securing portion 26 fits around the corner of the building. It can be used for either interior or exterior corners, though it may be desirable to arrange the hairlines 20 on opposite faces of the plate 24 for these two alternatives so that they occur on the face touching the back plate 12.

As seen particularly in Fig. 5, the edges of the various plates in the recesses 18 are provided with chamfers 28. The chamber on the front plate is on the bottom edge and the chamfer on the back plate is on the top edge, so that they form a V-shaped notch in the recess when the plates are brought together.

This assists in cutting the adhesive tape with a sharp instrument to release the plates from each other after they have been secured over a crack. If desired both plates could be chamfered on both top and bottom edges.

The plates 10, 12 shown in Figs. 1 and 2 can both be made from the same mould, the markings 20, 22 being applied subsequently.

WHAT WE CLAIM IS: 1. A method for the measurement of cracks in buildings, comprising securing two plates to the building, at respective securing points each on a respective side of the crack to be measured, so that the plate are in overlapping relationship and slidable over each other as the crack opens or closes, each plate being provided with markings which move rigidly with the side of the crack on which the corresponding plate is secured, by means of which the movement of one plate with respect to the other can be directly estimated in terms of the movement of the markings with respect to each other, and subsequently monitoring the movement of the markings with respect to each other to provide a direct indication of the movement of the crack.

2. A method according to claim 1 wherein the markings comprise a scale on one plate with graduations extending along two axes at right angles to each other, and lines on the other plate to indicate the movement of the other plate along the axes.

3. A method according to claim 1 or claim 2 wherein the plates are attached together as a unit prior to securing the plates to the building.

4. A method for the measurement of cracks in buildings substantially as herein described with reference to the accompanying drawings.

5. A gauge for the measurement of cracks in buildings, comprising two plates each having a portion provided with markings, there being provided as an integral part of at least a first one of said plates a securing portion which projects with respect to the portion of that plate which has markings, whereby the plates can be secured one on each side of a crack to be measured, the securing portion of the first plate offsetting the portion thereof which has markings so as to be in a slid able overlapping relationship with the portion of the other plate which has markings, whereby the movement of the markings with respect to each other provides a direct indication of the movement of the crack.

6. A gauge according to claim 5 wherein the projecting securing portion of the first plate is provided by a portion of the first plate which is thicker than the portion with markings.

7. A guage according to claim 5 wherein the projecting securing portion of the first plate is an upstanding portion thereof, whereby the plate can be secured at the corner of a building.

8. A gauge according to any one of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. masking tape could be used, but a transparent adhesive tape such as "Sellotape" (registered Trade Mark) enables the scale markings to be seen. The point at which the hairlines 20 on the front plate 10 cross overlies the central origin 23 of the scale region 22. Preferably the hairlines 20 and scale region 22 are formed on those faces of the front plate 10 and back plate 12 which touch each other, in order to reduce parallax error. The assembly thus formed is placed over a crack, for example in a wall of a building, which it is described to monitor. One end region 14 is placed on one side of the crack, while the other end region 14 is placed on the other side of the crack. The assembly is then secured in place on the wall straddling the crack by means of screws through the holes 16. The adhesive tape can then be removed, or alternatively it can be left in place as it will deteriorate in time and in any case will not be as strong as the securing provided by the screws through the holes 16. In time, as the crack in the wall of a building opens or closes, the positions of the hairlines 20 over the scale region 22 will change because one plate is secured to one side of the crack while the other is secured to the other side of the crack. The movement can thus be monitored at intervals.Because the scale graduations extend in all directions from the origin 23, relative movement of either side of the crack can be measured whatever the direction of movement. Fig. 4 shows an alternative form of front plate 24, for use where the crack to be monitored is near a corner of the building. The front plate 24 is intended for use with the back plate 12 seen in Figs. 2 and 3, and is generally similar to the front plate 10 of Fig. 1 except that instcad of a thickended end portion 14 of the plate it has an upstanding securing portion 26 at one end of the plate and at right-angles thereto. This securing portion 26 is provided with the screw holes. It is used in exactly the same manner as the plate 10, except that the securing portion 26 fits around the corner of the building. It can be used for either interior or exterior corners, though it may be desirable to arrange the hairlines 20 on opposite faces of the plate 24 for these two alternatives so that they occur on the face touching the back plate 12. As seen particularly in Fig. 5, the edges of the various plates in the recesses 18 are provided with chamfers 28. The chamber on the front plate is on the bottom edge and the chamfer on the back plate is on the top edge, so that they form a V-shaped notch in the recess when the plates are brought together. This assists in cutting the adhesive tape with a sharp instrument to release the plates from each other after they have been secured over a crack. If desired both plates could be chamfered on both top and bottom edges. The plates 10, 12 shown in Figs. 1 and 2 can both be made from the same mould, the markings 20, 22 being applied subsequently. WHAT WE CLAIM IS:

1. A method for the measurement of cracks in buildings, comprising securing two plates to the building, at respective securing points each on a respective side of the crack to be measured, so that the plate are in overlapping relationship and slidable over each other as the crack opens or closes, each plate being provided with markings which move rigidly with the side of the crack on which the corresponding plate is secured, by means of which the movement of one plate with respect to the other can be directly estimated in terms of the movement of the markings with respect to each other, and subsequently monitoring the movement of the markings with respect to each other to provide a direct indication of the movement of the crack.

8. A gauge according to any one of

claims 5 to 7 wherein the markings comprise a scale on one plate with graduations extending along two axes at right angles to each other, and lines on the other plate to indicate the movement of the other plate along the axes.

9. A gauge according to any one of claims 5 to 8 wherein the back plate is provided with a scale and the front plate with an indicator line lying over the scale in use.

10. A gauge according to any one of claims 5 to 9 wherein the front plate is transparent or has a transparent portion under which the markings on the back plate lie in use.

11. A gauge according to any one of claims 5 to 10 wherein the front and back plates are or are adapted to be attached together as a unit prior to securing the plates to the building.

12. A gauge according to claim 11 wherein the edges of the plates are provided with matching recesses, whereby the plates can be attached together by wrapping tape around them, the recesses locating the tape.

13. A gauge according to claim 12 wherein each recess has a chamfered edge, the chamfers on the two plates co-operating to form a V-shaped notch in the recesses when the plates are attached together.

14. A gauge for measuring cracks in buildings, substantially as described herein with reference to Figs. 1 to 3, or Figs. 2 to 4.