Repairs: walls

Stepped cracking and oversailing of the wall, which then hangs out above the DPC line and the wall beneath (which is restrained by the ground around the foundations), is still commonly seen in all types of masonry.

Be aware of the problems this can cause and refer to brick design tables (such as those in the Building Regulations Approved Document A, Section 2C, or published by the Brick Development Association) for guidance on how to help prevent this.

However, the problem is not confined to shrinkable silicate-type bricks, and any clay brick, as well as concrete or composition bricks, will be prone to movement, thermal expansion and some initial moisture-induced dimensional changes.

Often building designers under pressure to supply only minimal information on working drawings, leave a window open for considerable interpretation on site. The results are not always favourable – insufficient tying-in being a typical occurance.

Solution

In long walls, consider expansion joints. They may also be needed in short walls if the material is particularly prone to shrinkage/movement.

In either case, appropriate detailing (extra wall ties) around doors and windows and expansion joints is essential.

Expansion joints are not pretty, but they can be recessed if necessary by a return in the wall line (often an ideal place to position the rainwater downpipe to hide the fibre or mastic strip sealing the expansion joint).

Oversail above a DPC