GB2135377A

GB2135377A - Damp proof course

Info

Publication number: GB2135377A
Application number: GB08304585A
Authority: GB
Inventors: Christopher John Greenup
Original assignee: DRYSTAT Ltd
Current assignee: DRYSTAT Ltd
Priority date: 1983-02-18
Filing date: 1983-02-18
Publication date: 1984-08-30
Also published as: GB8304585D0

Abstract

The mortar of a wall 34 is removed at spaced-apart locations AB, CD. Inflatable, impervious, sealable plastics envelopes 2 having non-inflatable end flaps 12, 14 are inserted into the spaced-apart slots and filled with a quick-setting waterproof mortar which is injected under pressure through valve 16. The mortar BC remaining between the envelopes 2 is removed and an inflatable, impervious, sealable envelope 20, having no end flaps, is inserted into the slots BC and is such that the envelope 20 and the flaps 12, 14 of the adjacent envelopes 2 overlap. The envelopes 20 are filled with a quick-setting waterproof mortar through valves 16 and thus press down tightly on the flaps 12, 14 of adjacent envelopes 2, thus forming a continuous damp-proof course along the wall. The pressurised mortar in the sealable envelopes 2 supports the wall 34 even before the mortar has set and allows the remaining mortar BC to be removed without delay. <IMAGE>

Description

SPECIFICATION Damp-proof courses This invention relates to a method of providing a damp-proof course (DPC) in the walls of buildings, or the like, where DPC has not been provided, or the existing DPC has deteriorated or broken down and no longer provides a physical barrier to rising water.

A damp-proof course (DPC) is a physical barrier to water, which is usually inserted about 1 50 mm above natural ground level. The barrier is not necessarily horizontal as vertical DPC's are used to prevent the passage of water from adjoining structures.

Any dampness in building is unpleasant and unhealthy and rising damp is no exception.

Affected areas are cold, decorations are damaged, moulds may grow and paper peels from the walls.

Further, rising damp may cause floor timbers to become damp and to be attacked by dry rot, which may spread to other timbers.

Bricks, stone and mortar, and similar materials, are porous and ground water carrying dissolved salts may rise many feet up a wall by capillary action unless preventative measures are taken.

Generally, the finer the capillaries, the higher the water will rise against gravity.

In most houses built before the turn of the century, a DPC was not installed during the construction stage. It is now compulsory to insert some form of DPC during construction and these can take the form of bitumen, epoxy composites, polythene, aluminium, copper or lead sheet, or slate or engineering bricks in cement mortar.

However, in many buildings, the DPC has failed due to insufficient laying or deterioration with age, it may have cracked because of settlement or perished because of chemical reaction or breakdown.

Where DPC's have not been laid or have failed, rising damp can be remedied by inserting a new DPC into the affected walls as a physical barrier to the rising water. A DPC can be inserted in walls of existing buildings, and in the past this has been a slow, tedious and relatively expensive procedure.

According to known method, two or three adjacent bricks are removed from the damp affected wall along the line of the proposed new damp-proof course, a new membrane is then laid along the top of the exposed lower bricks and the bricks are then replaced, usually with new bricks because the process of removing the old bricks causes them to become severely damaged. As the new bricks are being replaced the mortar which is to be used to set the bricks into place and which is to fill up the spaces between the bricks must be applied laterally instead of from the top of each brick as it is when the wall is being built. This means that the mortar invariably slips off the bricks as it is being manoeuvred into place with the result that the wall does not have sufficient vertical support.This invariably results in most walls which have been treated in this manner, subsequently subsiding and causing cracks to appear and window frames or door frames to distort. in the case of a wall of thickness greater than one brick the problem of applying the supporting mortar in such a manner as to ensure sufficient upwards thrust is insurmountable.

Pressure grouting of mortar has been attempted in the past in order to ensure that mortar covers the bricks throughout the entire thickness of the wall, but because the space between the new bricks form a slot which is open at the back, the incoming mortar from the pressure device has nothing against which it can build up in order then to commence thrusting upwards and thus providing the necessary support to the wall.

A further objection to the traditional method of installing a new DPC into an existing wall is the fact that it is a time consuming job not only because of the need to remove and relay bricks etc., but also the fact that the mortar must be allowed time to set before the next succeeding section of walling can be treated. It is also expensive and creates considerable upheaval in the home or building being treated. In more recent times saws have been used to cut a transverse slot along a line of mortar jointing and a new membrane has been inserted in the slot so formed.

The same objections regarding the complete fillir.g of the slot with mortar which will provide an immediate and positive upwards thrust apply as described above.

An improvement on the traditional method is described in U.K. Patent Application 7931884 and describes a method comprising cutting a slot transversely through the wall along the proposed line of the DPC, inserting an elongate sealable bag or envelope into the slot, filling the bag or envelope under pressure with a quick setting waterproof material and allowing said waterproof material to set solid and to support that portion of the wall above the set waterproof material.

However, disadvantages of this system are that only a short length of wall can be fitted with a DPC at a time, since it is undesirable to leave too great a length of wall unsupported. Also, although the application describes flaps which can overlap one another, the two flaps are not tightly pressed together, and sometimes gaps are left inbetween adjacent bags or envelopes.

It is an object of the present invention to provide a method which is quicker than previously known methods, can be applied to any length of wall, and provides an improved DPC.

Accordingly, the present invention provides a method of inserting a damp-proof course into an existing wall of a building, comprising forming at least two spaced apart first slots in the wall leaving a length of intact wall between the first slots, inserting a first inflatable, impervious, sealable device in each first slot, filling each first device with a settable mixture, sealing each first device, removing material between the first slots to Form at least one second slot, inserting a second inflatable, impervious, sealable device in the or each second slot, the first and second inflatable, impervious, sealable devices being arranged to partially overlap, filling the or each second device with a settable mixture such that the first and second devices are tightly pressed together where they overlap and sealing the or each second device.

Preferably the settable mixture comprises a quick setting waterproof material.

Preferably the first and second devices are wider than the width of the wall and after the settable mixture has set, those portions of the devices protruding from the wall can be cut off flush with the face of the wall.

Preferably the first device comprises an elongate envelope of tough plastics material and is inflatable by means of a valve, the envelope being provided with a non-inflatable flap at each end.

Preferably the second device comprises an elongate envelope of tough plastics material and is inflatable by means of a valve.

Preferably part of each second device, when inserted in the uninflated condition, overlaps a flap of a first device, so that the two devices are tightly pressed together when the second device is filled.

Preferably the upper and/or lower surface or surfaces of each device are coated with adhesive or mortar material to provide adhesion to the or each adjacent surface of the wall.

it is another aspect of the invention to provide a particularly effective inflatable device for use with such a method.

Accordingly the invention also provides an inflatable, impervious, sealable device comprising an envelope of tough plastics material, having a valve comprising a flexible, resilient material arranged on the inside of a hole in the inflatable device such as to allow material to enter under pressure, but prevent material from leaving the device again when the device is substantially full.

Preferably the hole in the inflatable device is reinforced with an eyelet.

Preferably the elongate envelope is such that when it contains settable mixture under pressure the flexible resilient material is urged against the eyelet to seal the envelope.

The eyelet may be arranged for connection to an injection nozzle.

By way of example, a specific embodiment of the invention will now be described, with reference to the accompanying drawings, in which: Figure 1 is a plan view of a first bag used in the embodiment; Figure 2 is a front view of the bag shown in Figure 1; Figure 3 is a plan view of a second bag used in the embodiment; Figure 4 is a front view of the bag shown in Figure 3; Figure 5 is a view of part of a wall after the fitting of the first bag; Figure 6 is a view of the wall shown in Figure 5, after the fitting of the first and second bags; Figure 7 is a detailed view of part of the wall as shown in Figure 6; and Figure 8 is a view of a valve used in the first and second bags, in scrap section.

Referring firstly to Figures 1 and 2, a first bag is indicated generally at 2. This comprises a sheet of tough plastics which has been foided back on itself and sealed along lines 4, 6, 8 to provide a relatively flat, long envelope 1 0. This leaves two flaps 12 and 14 which are open at 13 and 1 5 respectively. Provided in one edge of the envelope 10 is a valve 1 6, to be hereinafter described. The bag 2 is wider than the width of wall to be treated, the reason for which will become apparent.

Referring now to Figures 3 and 4, a second bag is indicated generally at 20. The second bag is of similar construction to the first bag 2 except that all the seals are very close to the edges of the plastics as at 6a and 8a, and substantially no flap remains. Bag 20 is provided with a valve 1 6 as in bag 2, and is o;F the same width as bag 2.

The construction of valve 1 6 is shown in Figure 7. It will be described with reference to bag 2, although it will be appreciated that a similar description applies to bag 20. A hole 26 is formed in one edge of the bag and is reinforced by a metal eyelet formed by two annuli 22, 24. Behind the hole 26 is a flexible rubber sheet 30 which is secured to the plastics of the envelope 10 by staples 32 (not all the staples are shown). If unset mortar is pumped under pressure into the valve, by connecting a delivery nozzle to the eyelet, the portions of rubber sheet 30 not attached by staples are forced back by the mortar away from the envelope 1 0, allowing the mortar to enter the envelope 10 and inflate it.When the envelope is full or mortar, the back pressure of the mortar in the envelope 10 presses the rubber sheet 30 tightly against the annulus 22 and prevents any mortar from coming out of the hole 26. The rubber sheet 30 thus acts as a non-return valve.

To provide a wall 34 with a damp-proof course according to the embodiment of the invention involves the following stages. In the first stage, slots such as AB and CD are cut from the existing mortar 36 of the wall, preferably by means of a ring saw or by a specially adapted chain saw. The slots AB and CD are substantially the same length, or slightly longer than the length of bag 2. The slots are spaced apart to leave sections of mortar, such as BC in Figure 5 so that support for the weight of the wall is maintained. The sections of mortar such as BC are of such a length that when bags 2 are slid into apertures AB and CD the distance between adjacent seals 6 and 8 is substantially equal to the length of bag 20, i.e. so that the lengths such as EF in Figure 5, are equal to the length X of bag 20 in Figure 3.

In the second stage, uninflated bags 2 are slid into the slots in the mortar 36, and a quick setting waterproof cement mortar is injected into the envelopes 10 from a pump through valves 1 6.

When the envelopes 10 are full with mortar, the mortar supply is disconnected. The pressure of the mortar within the envelope 10 pushes the rubber sheet 30 against the annulus 22 and closes each valve, thus preventing the cement from coming out of the valve and allowing the associated envelope 10 to support part of the weight of the wail even before the mortar inside the envelope has set, since the mortar is under pressure.

At any time after two adjacent bags 2 have been inflated the third stage may be begun, namely the mortar remaining between two adjacent bags 2, for example that shown as BC in Figure 5, may be removed, since the bags 2 on either side now support the weight of the wall, even though the mortar in them may not yet be set. However it is usually better to wait until the mortar within bags 2 has set before the remaining mortar is removed and bags 20 are inserted.

The fourth stage involves sliding bags 20 into the new gaps, such as BC, such that the ends of bags 20 overlap the flaps 12, 14 as in Figure 6.

The bags 20 are then filled in the same manner as bags 2. When fully inflated, the ends of bags 20 press tightly against the flaps 12, 14 of bags 2, and in this way a continuous impervious face seal is produced.

When the mortar in the bags 2, 20 has set, the valves 1 6 and the exposed edges of the inflated bags can be cut off flush with the wall, since the bags overhang the brickwork on each side of the wall, and this comprises the fifth stage. The exposed mortar may, if desired, be painted to be of the same colour as the rest of the mortar. The whole operation provides a damp-proof course of at least two layers of tough, impervious plastics material, the two layers being separated in most places by a layer of waterproof mortar.

The invention is not restricted to the details of the foregoing embodiment. For example, the bags 2 and 20 may be filled with a settable epoxy material which is mixed by means in the valve 16.

Claims

1. A method of inserting a damp-proof course into an existing wall of a building, comprising forming at least two spaced-apart first slots in the wall leaving a length of intact wall between the first slots, inserting a first inflatable, impervious, sealable device in each first slot, filling each first device with a settable mixture, sealing each first device, removing material between the first slots to form at least one second slot, inserting a second inflatable, impervious, sealable device in the or each second slot, the first and second inflatable, impervious, sealable devices being arranged to partially overlap, filling the or each second device with a settable mixture such that the first and second devices are tightly pressed together where they overlap and sealing the or each second device.

2. A method as claimed in claim 1, in which the settable mixture comprises a quick setting waterproof material.

3. A method as claimed in claim 1 or claim 2, in which the first and second devices are wider than the width of the wall and after the settable mixture has set, those portions of the devices protruding from the wall can be cut off flush with the face of the wall.

4. A method as claimed in any one of claims 1 to 3, in which the first device comprises an elongate envelope of tough plastics material and is inflatable by means of a valve, the envelope being provided with a non-inflatable flap at each end.

5. A method as claimed in claim 4, in which part of each second device, when inserted in the uninflated condition, overlaps a flap of the first device, so that the two devices are tightly pressed together when the second device is filled.

6. A method as claimed in any one of claims 1 to 5, in which the second device comprises an elongate envelope of tough plastics material and is inflatable by means of a valve.

7. A method as claimed in any one of claims 1 to 6, in which the upper and/or lower surface or surfaces of each device are coated with adhesive or mortar material to provide adhesion to the or each adjacent surface of the wall.

8. An inflatable, impervious, sealable device comprising an envelope of tough plastics material, having a valve comprising a flexible, resilient material arranged on the inside of a hole in the inflatable device such as to allow material to enter under pressure, but prevent material from leaving the device again when the device is substantially full.

9. A device as claimed in claim 8, in which the hole in the inflatable device is reinforced with an eyelet.

10. A device as claimed in claim 9, in which the elongate envelope is such that when it contains settable mixture under pressure the flexible resilient material is urged against the eyelet to seal the envelope.

11. A device as claimed in claim 9 or claim 10.

in which the eyelet is arranged for connection to an injection nozzle.

12. A method of inserting a damp-proof course into an existing wall of a building, substantially as herein described, with reference to the accompanying drawings.

1 3. An inflatable, impervious, sealable device, constructed and arranged substantially as herein described, with reference to Figures 1 to 4 cf the accompanying drawings.