Wednesday, October 30, 2013

Bricklaying




The most critical consideration when designing a freestanding wall is to make sure that
it is adequate to resist severe gusts of wind. For walls no more than two metres in
height there are simple guides that provide adequately stable construction. A good guide
is Building Research Establishment Good Building Guide 14 Building Simple Plain Brick or
Blockwork Freestanding Walls. For walls greater than two metres in height advice of a
structural engineer should be sought.
The following types of construction can be selected for stability. Piers may be
incorporated preferably projecting both sides of the wall. Alternatively, if space permits,
staggering or curving the wall in plan is an option. For greater stability or taller walls,
diaphragm forms, reinforced piers and chevron plan shapes can be considered.
Regardless of the structural requirements, detailing is extremely important in order to
protect the brickwork from deterioration by the weather and to develop features for
interest. A freestanding brick wall is far more exposed to weather conditions than an
external wall in a building.
First the wall should incorporate a damp proof course at its base consisting of two
courses of DPC bricks. A flexible sheet DPC is not recommended as this can affect
stability. At the top, a coping or capping brick will be required depending on the
durability designation of the bricks selected. If 'M' (Moderately frost resistant) bricks are
chosen, a coping will be needed that projects a minimum of 50mm each side
incorporating a throated drip. In addition a flexible high-bond DPC such as a bitumen
polymer giving good bond strength sandwiched between mortar will be needed below it.
If an 'F' (Frost Resistant) brick is selected, a capping will be adequate but it is
recommended that the same kind of high bonding DPC is included below it to protect the
brickwork from possible staining. Both capping and coping materials must be frost
resistant. Movement Joints will be required if the wall is over about ten metres long.
Mortar mixes should be compatible with brick types and suitable for the level of
exposure. Generally the main body of wall should be designation (III) or (II) and for the
coping /capping course (II) or (I). Sulfate resisting cement may be necessary with bricks
of 'Normal' soluble salts content.
As most freestanding walls will be at least one brick thick they will provide an
opportunity to use one of the Garden Wall Bonds. If it is to be fair faced both sides, it
may be necessary to select bricks for the through the wall headers for size consistency.

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