Wall Consolidation/Stabilisation

Construction:  600mm thick stone walls.

Problem: The construction consists of an outer and inner layer of stone with random rubble infill. The outer layer is bulging away from the inner one.
Typical symptoms are pictured below including the appearance of a gap in a reveal where the wall has moved away from the window frame and internally where a gap has opened up between the wall and skirting. 

Wall stabilisation actions:  For this type of consolidation anchors are typically installed at the same density as for standard wall ties,at staggered centres.

Crack Stitching Project

Construction – Solid 225mm brick wall

Remedial action

Crack stitches are usually installed in every third or fourth joint (or as specified by engineer) as shown on the photo above. They are generally 1m long (ie to extend 500mm either sided of the crack) and, in the case of the Joint Remedial Anchor system, are installed 50mm into the joint.

Wall Stitching Project

Construction:

Brick cavity wall.

The problem/cause of cracking:

The front elevation was coming away from the building.

Wall stabilisation actions:

Anchors were installed in a staggered pattern (see diagram below) at one metre vertical centres.  The uppermost set of anchors is always installed approximately one metre below the top of the wall ie. there needs to be about a 1 metre weight of wall above the first anchor.

The anchor lengths are varied/staggered to avoid a concentration of stress in any one vertical line.

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Stabilisation of solid walls

Construction – This property has solid walls which are mostly stone with some sections of brickwork evident externally. The front and end elevations are rendered.   

The Problem – There is relatively minor cracking to the external walls which can be seen particularly around windows and over doorways indicating that the walls are moving slightly. They can be restrained by tying back into the floor joists using lateral restraints.

Stabilisation Actions - Anchors are installed through the walls into the joists at one metre centres. Where the joists run parallel to the wall the anchors should extend through at least three joists.  

 Anchors fitted prior to inflation with the grout.  The anchors pass approximately through the centre of the joist depth.

When the grout is injected the sock inflates the sections between the joists, locking the anchor tightly in position.

Where the joists run at 90 degrees to the wall stainless steel arm locks, which are coach bolted to the adjacent joists, can be used.  For this application stud anchors with a threaded end are fixed into the wall.  The arm lock is secured and tightened to the anchors.

An alternative method is to fit a timber noggin between the joists and use a standard RHS anchor.

An important consideration with lateral restrains is to ensure the integrity of the joists being fixed to.  It may be necessary to secure joists together where they meet in the middle of a building, for example, as shown below.

    

Wall stabilisation - wall strengthening project

Construction -  Solid brick built boundary wall 340mm thick x 1.2m high with a concrete capping.

The Problem:

This was an unusual project. The boundary wall to this parking area was being damaged by vans as they drove in and out. The local residents would not allow the wall to be removed or rebuilt, so it needed to be reinforced to withstand the abuse of the vans.   

Wall Strengthening Actions:

The capping was temporarily removed and anchors were installed vertically (at a slight angle) every metre.

Click for more information on wall stabilisation and strengthening.