GB2177444A - Method of modifying a wall - Google Patents

Abstract

The invention relates to a method of modifying a wall having an inner skin (13) and an outer skin and one or more upright supports (6) to which the skins are coupled. The method comprises decoupling and removing at least part of the outer skin; providing a plurality of concrete blocks (15) having internal cavities (16); cutting an entry slot (18) through a wall of each block (15) into the cavity (16); and building a load bearing wall (14) of the blocks wherein at least part of the or each support (6) extends through slots (18) in respective blocks in the load bearing wall into the cavities. <IMAGE>

Description

SPECIFICATION Method of modifying a wall The invention relates to a method of modifying a wall of the kind having inner and outer skins and one or more upright supports to which the skins are coupled. Such a wall is hereinafter referred to as of the kind described.

Walls of the kind described are most commonly found in houses built with precast concrete panels.

Typically, such houses have a plurality of upright concrete supports which may be secured to a ground floor slab or substructure. The panels are either coupled to the supports by wires passing around the supports and connected to the panels or by other mechanical fixing means. The supports typically have a central, hollow steel tube extending throughout the length of the support as reinforcement.

Typically, the inner skin is provided by sets of plasterboard, hardboard orfibreboard panels or blockwork.

Recently, problems of instability have arisen in these houses. This is primarily due to the reduced load carrying capabilities of the reinforced concrete supports caused by cracking of the concrete and corroded reinforcement. Cracking can be caused by damage during construction, lack of cover to the reinforcement and/or carbonation of the concrete.

Corrosion takes place following the ingress of moisture. There is therefore a requirement for some means of dealing with this problem.

There are a very large number of houses having this type of structure and in the past, it would be necessary to evacuate the occupants of the house while extensive repairs were carried out. In view of the number of houses involved, this would be very costly and it is desirable to devise some method of reducing these costs.

In accordance with the present invention, a method of modifying a wall of the kind described comprises decoupling and removing at least part of the outer skin; providing a plurality of blocks having internal cavities; cutting an entry slot through a wall of each block into the cavity; and building a load bearing wall of the blocks wherein at least part of the or each support extends through slots in respective blocks in the load bearing wall into the cavities.

The invention deals with the problems mentioned above by providing a load bearing wall partially surrounding the supports so as to remove the load previously carried by the supports.

This method has a number of important advantages. Firstly, the inner skin can remain in place and untouched, and where the wall forms a wall of a house, the occupants will be relatively undisturbed while the method is being carried out.

Secondly, the invention enables conventional hollow concrete blocks to be used. Thirdly, the step of cutting an entry slot can easily be carried out on site. These latter two advantages in particular reduce the overall cost of modifying the wall.

Preferably, the blocks are united by filling aligned cavities in the blocks with a solidifying material which may simply be poured into the cavities and compacted.

In some examples, each block has two cavities, one of which receives a support and the other of which is filled with solidifying material.

In other examples, each cavity receiving a support may be filled with solidifying material whereby after solidification the block is united with the support.

Typically, the load bearing wall will also comprise blocks, additional to those which receive supports.

Conventional hollow concrete blocks typically include two internal cavities and are of a size such that, following bonding, one of the cavities will be positioned between adjacent supports in a typical wall of a house. Preferably, the method further comprises providing an insulating material which may be adjacent the inner skin or the outer surface defined by the load bearing wall. Conveniently, this is provided on the side of the inner skin facing the outer skin so as to minimise disruption to the inside of the inner skin. The insulation provides a weatherproof layer to minimise the disruption of the existing inner skin during reconstruction.

In some cases, the outer surfaces of the blocks can themselves define the outer surface of the wall.

However, in other examples, a brick or other material facing such as an outer skin may be constructed subsequently to the step of filling the cavities and be tried to the blockwork to define a cavity between the two. Where there are existing doors and windows the facing and wall are constructed to accommodate these.

An example of a method according to the invention for modifying the walls of a house will now be described with reference to the accompanying drawings, in which: Figure 1 is an end elevation of the house; Figure 2 is a horizontal section through part of a wall of the house before modification; Figure 3 is a section similar to Figure 2 but of the wall after modification; and, Figure 4 is a vertical section through part of the wall after modification.

An end elevation of a typical prefabricated house of the Airy type is illustrated in Figure 1 and has an end wall 1 including a lower section 2 and an upper section 3. The lower section 2 includes a door opening 4. A roof 5 is supported above the upper section 3. However, it should be noted that the individual configuration can vary from house to house.

The lower section 2 comprises a plurality of vertical supports 6 two of which are illustrated in Figure 2. Each support 6 has a central steel tube 7 surrounded by a concrete column 8 having a rectangular cross-section. The bases of the supports 6 rest on foundations 9 (Figure 4).

Between each pair of supports 6 are positioned a plurality of precast concrete panels 10, one above the other. Panels 10 which are adjacent to one another in a horizontal direction are coupled to the corresponding supports 6 by a tensioned wire tie 11 extending around a vertical wooden batten 12 adjacent the support 6. Alternatively the panels may be secured by other mechanical fixing means to support 6.

An internal skin or lining is also provided by a plurality of plasterboard panels 13 nailed to the battens 12.

The upper section 3 of the wall 1 is formed in a similar manner two the lower section 2 with supports 6 resting in alignment with the supports 6 of the lower section 2.

In view of the length of time for which the supports 6 have been in existence, the concrete cladding 8 at the base, at first floor level, and at the roof junction of the support 6 is cracking. This has allowed moisture to corrode the steel tubes 7 leading to deterioration of the support and instability of the house.

To deal with this problem, the walls of the house are refurbished in sections. For example, all the panels 10 of the section 2 of the wall 1 are removed by decoupling them from the supports 6. The wire ties are also removed together with any spalled concrete and debris.

A damp proof course 27 (Figure 4) is provided.

A new load bearing wall 14 is then constructed from conventional, hollow concrete blocks 15 each of which has a pair of cavities 16, 17. An entry slot 18 is cut through a wall of the hollow concrete blocks 15forcommunication through that wall with the respective cavities 16. The size of the slot 18 is chosen to be slightly greater than the width of the supports 6.

The blocks 15 are laid down in courses with the cavities 16, 17 in alignment. Mortar is provided between both horizontal and vertical courses to bond the blocks together. In this example each concrete block 15 is slotted around a respective support 6 with each support 6 extending through the slots 18 into the cavities 16. A plurality of hollow concrete blocks 15 will be stacked one above the other in association with each support 6. In other examples (not shown) additional vertical courses of blocks 15 may be used which are not associated with supports 6.

Between some of the horizontal courses a first set of wall ties 19 are provided which extend along opposite sides of the columns 6 and around the battens 12. A second set of wall ties 20 are also provided between alternate horizontal courses and extending outwardly.

Concrete 21 is poured into the cavities 17 as work proceeds to provide additional strength. In other examples (not shown) concrete is also poured into cavities 16 to unite the supports 6 with the hollow concrete blocks 15.

During this stage, the upper section 3 of the wall 1 is supported in any convenient manner as schematically indicated at 22 in Figure 1.

Once the load bearing wall 14 has been constructed, 25 mm thick polystyrene insulation 23 is fixed to the outer face of the wall 14 supported by the wall ties.

After the lower section 2 has been modified, the method is repeated on the upper section 3 and then on the other elevations.

An additional brick facing 23 is constructed spaced from the hollow concrete blocks 15 to define a cavity 24 and stabilised by the wall ties 20.

Additional foundations 25 are constructed linked to the existing foundations 9 by ties 26 to support the brick facing 23.

Claims (7)

1. A method of modifying a wall of the kind described, the method comprising decoupling and removing at least part of the outer skin; providing a plurality of blocks having internal cavities; cutting an entry slot thorugh a wall of each block into the cavity; and building a load bearing wall of the blocks wherein at least part of the or each support extends through slots in respective blocks in the load bearing wall into the cavities.

2. A method according to claim 1, wherein the blocks are united by filling aligned cavities in the blocks with a solidifying material.

3. A method according to claim 1 or claim 2, wherein each of the plurality of blocks has two internal cavities.

4. A method according to claim 3, when dependent on claim 2, wherein solidifying material is provided in the cavity of each block which does not receive a support.

5. A method according to any of the preceding claims, further comprising providing an insulating material adjacent the load bearing wall.

6. A method according to any of the preceding claims, further comprising constructing an outer facing spaced from the load bearing wall.

7. A method of modifying a wall of the kind described substantially as hereinbefore described with reference to the accompanying drawings.