Repairs: walls

Two key considerations when a new wall is to be joined to an existing wall (perhaps for an extension) are:

1. Will the contractor use a modern metric brick and tooth it into older imperial gauge brickwork? This often looks unsightly because the new bricks are tipped and angled to fit into the existing mortar courses and the join becomes conspicuous.
2. Is there any risk of even quite minor building movement between the new extension settling down and the pre-existing structure? If so, any toothing in may well result in the tooth bricks cracking or snapping across the abutment joint or the joint pulling open.

Solution 1

Using metal connector plates generally provides a neat solution in most circumstances (see solution 2). The plate is bolted to the wall at the join line and metal wall ties are locked in at the appropriate intervals to bond in the new work to the old existing structure. Even if the courses are mismatched, at least there is a relatively neat butt joint.

It is advisable to inset the new work slightly from the face of the old wall to provide a relief angle or shadow line which can mask any relatively minor imperfections and create a more pleasing transition from old to new.

Solution 2

For a historic building it may be better to spend more on imperial gauge bricks and go for a carefully toothed-in join. Alternatively, set the new wall back further from the face of the old to provide a larger shadow line to help conceal the joint. Or conceal the joint behind a rainwater downpipe.