External wall issues

Defects in walls (throughout the century)

Poor tying-in of front and rear walls to party walls is a known defect. It can manifest in front and rear wall lean, but is unlikely to result in sudden collapse unless disturbed. Walls can be stitched back together by either partial rebuilds or proprietary stitching systems such as Helifix. The use of timber coursing beams in lime mortar walls remained popular in the 19th century: these are prone to rot, causing the wall to bow or crack horizontally. As brick walls tended to be over-designed, it is a fairly straightforward process to stitch in new bricks, but it is important to use replacement bricks of a similar standard.

The Victorians also introduced a variation of the coursing timber by inserting hooped iron into mortar beds, to reinforce them. These can sometimes expand, pushing walls out, but it is thought that, nationally, this problem has mainly been dealt with.

Check walls carefully for plumb or signs of bowing. Assess in light of the bond and determine whether they are solid or hollow. Do not assume that walls are solid. The thickness of the wall can be measured and evaluated in relation to the type of brick bond, but in reality there is no definitive way of knowing if a wall is hollow or solid.

It was accepted practice to use the good quality expensive bricks to the front, and poorer quality bricks to the rear, side and party walls.

Cement render (post-1824) was also used to coat the facade, which meant that cheaper bricks and hollow bonds could be used. If renders are removed and not replaced, these inferior walls will be prone to a higher risk of water penetration. These are probably the only circumstances where it can be advantageous to use modern renders to bolster a wall's performance, if all other techniques have been exhausted.

Poor brick quality (throughout the period in cheaper terraced housing)

Victorian mass production should not be assumed to imply unified quality. Rogue bricks laid in rear and partition walls can cause water penetration or unusual wicking behaviour. Damp spots in isolation half-way up walls are typical of this defect.

Shallow footings

Foundations were usually formed by removing the topsoil until a firm base was found. A splayed or stepped brick footing would be laid to carry the main load-bearing walls. It is common to find footings just below the surface, and some movement can be caused by local heave or subsidence. Some movement can be seasonal, and long-term monitoring can confirm this, making remedial work unlikely if the movement is containable. Hollow walls or cavities may not extend to the footings.