Wednesday, 25 July 2012

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.