The document discusses various types of defects that can occur in brick walls, including cracking from ground movement, thermal movement, restraint in cavity walls, and tie failure in cavity walls. It also describes defects such as spalling of brick faces from frost damage, deterioration of brick arch lintels when the timber lintel decays, and cracking around windows from corrosion of reinforcement bars in brick arches.

1. Defective
wall
•Size of bricks are
not same
•Quantity of
mortar in bricks
varies
•Plastering is not
perfect
,somewhere more
or less

2. Defects in bricks
Different kind of defects are:
•Cracking can occur in brickwork for a number of
reasons:-
•Ground movement leading to foundation failure
•Rapid change in load leading to disproportionate
settlement
•Mobile ground water undermining foundations
•Thermal movement
•Wall rotation due to lateral instability
•Excessive lateral loads on walls
Accident

3. Brickwork Cracks
Diagonal Cracks
• Cracks that are the result of ground movement tend to
be diagonal in nature with vertical cracks showing as
hairline at the point of rotation and wider further away.
Examination of the variation in crack width will reveal
which part of a wall has dropped, or, conversely, risen.
Similarly examination of junctions with cross walls will
often reveal an opening of a vertical crack showing the
direction of movement both lateral and vertical.
• Similar cracking can be exhibited in older properties
with basements in which a timber wall plate carrying
the ground floor has rotted thus allowing localised
compression below heavily loaded sections of wall.

4. Vertical Cracks
• Vertical cracks close to external corners can be the result of excess
restraint in cavity construction or the result of thermal movement.
In theory the movements causing these cracks is fully reversible
such that the cracks should close during warmer weather and open
once again when cooler. In practice small pieces of debris lodge in
the crack restricting the degree of closure. The effect is that cracks
widen over time and then stabilize with little visible movement
taking place.
• Along extensive brickwork elevations cracks will be seen at
approximately 12 metre centres (particularly if exposed to full
sunlight for much of the day). This is the natural limit to which
brickwork can withstand thermal movement. In new construction
joints are inserted at these locations to accommodate this
movement

5. Patchwork Cracks
• The formation of cracks in both bed and perp joints visible in
localised patches can be a sign of brick tie failure in cavity wall
construction. In less severe cases prior to the formation of cracks an
increase in porosity of the joints resulting in a wetter darker look
may be visible. Examination of the surface of the wall will reveal
undulation in the surface corresponding to the crack locations.
• Some types of cracking are visible only on the inside of a building.
This is particularly the case a problem prevalent in buildings
constructed before circa 1960 in which outward movement of the
gable wall results in a bulge at the mid-height. Cracks occur at the
junctions with ceilings. This is remedied relatively easily by
providing straps that tie the wall to a strong part of the building.

6. Face Spalling
• In older buildings the face of bricks or stonework can often
be seen to have spalled off. This is the result of alternate
exposure to frost and sun. Water droplets trapped in the
surface freeze and expand thus forming tiny stress failures
in the surface material. Exposure to the sun during summer
month will form expansion of the now loosened material
which may now fall away from the face. Repeated cycles of
this for many years results in increasing areas of wall
affected by the problem. In creased porosity of the surface
further accelerates the problem. Care is required in
repairing this defect as replacement of the worse affected
units while leaving less severe cases can in fact accelerate
the deterioration of those that have been left.

7. Brick Arch Lintels
• Brick arch lintels are popular in older properties constructed in solid
masonry. Wall thickness will vary according to the number of
storeys constructed above the one of interest. This will usually be
nine inch or thirteen inch construction. The outer face of the wall is
carried by a brick arch which can be flat or semi-circular. The
remaining thickness of wall is carried on a timber lintel.
Deterioration of the lintel will place increased load on the arch
which will in turn begin to fail. A common remedy for this has been
to insert a steel (or cast iron) bar below the arch. Eventually the bar
corrodes giving rise to horizontal cracks at the supports. This can
give the appearance that the pier between the windows has failed
but this may not be the case.
• The remedy for brick arch failure is to remove the timber lintel a
replace with a new timber or precast concrete lintel. The outer arch
can be repaired insitu by drilling vertically to insert stainless steel
pins fixed with resin injected into the hole.