Application Attributes

Water absorption

The % water absorption figures quoted have been calculated as the average percentage increase in the mass of bricks which have been immersed in water for a period of 24 hours. As a rough guide, the water absorption of individual face bricks ranges from 6.0 - 10.0% (average 8.0%).

Moisture expansion categories: clay face bricks

All burnt clay bricks demonstrate irreversible expansion after extended exposure to moisture. The extent of the expansion will vary according to brick type. It is advisable to insert vertical movement joints into horizontal lengths of walling, in order to accommodate this expansion. (see table below).

Provision for movement joints in brickwork

Category	%Moisture Expansion	Maximum Spacing of 10-12mm joints	Maximum Spacing of 10-12mm joints
		Horizontal Walling	Parapets
I	0.00 – 0.05	16m	11m
II	0.05 – 0.10	10m	8m
III	0.10 – 0.20	5m	4m

NB: Horizontal 10mm movement joints to be provided at every storey height of a clay brick infill panel to a concrete framed structure

1. Selecting bricks for external face brickwork applications

Exposure zone and durability
The durability of a material is assessed by its ability to withstand the effects of weathering agents. These include moisture, soluble salts and extremes of heat and cold. The degree to which weathering affects a building depends upon its geographic location, microclimatic conditions with reference to the building’s height and the actual position of the material on the building. Parapets and copings will clearly be affected by the weather far more than a façade protected by overhanging eaves. Bricks are a key element in the building process and we recommend that you consider the following when specifying bricks in Southern Africa.

The building’s exposure zone.
Southern Africa can be divided into four exposure zones, which are defined in SABS 0164 Part 2.

Zone 1 - Protected
All areas 30km or more inland from the coast.

Zone 2 - Moderate
The coastal belt extending up to 30km from the coastline, but excluding the spray zone.

Zone 3 - Severe:

• Sea spray zone. This includes areas at sea level on the east and north seaward sides of the Durban Bluff and other similarly exposed coastal headland areas.
• The 15km coastal zone which extends from Mtunzini to the Mozambique border. This includes Richards Bay and St Lucia.
• The coastal belt of Namibia.

Zone 4 – Extremely severe

• Area such as Walvis Bay, where the moisture from sea mist and high ground water tables, high soluble sulphates in the soil, and / or rapid temperature changes, combine to create the most severe exposure and weathering conditions in Southern Africa.
• Industrial areas where high acid and or alkali discharges occur.

SABS BRICK CLASSIFICATION

1. Plaster Brick
   1. NFP - NON-FACING PLASTERED
      Clay bricks suitable for general building work that is to be plastered
   2. NFX - NON-FACING EXTRA
      Clay bricks suitable for use, plastered or unplastered, for general building work where durability rather than aesthetics is the key selection criteria: below damp-proof course or under damp conditions or below ground level
2. Face Brick
   1. FBX - FACE BRICK EXTRA
      Clay bricks that are selected or produced for their durability and high degree of uniformity of size, shape and colour
   2. FBS - FACE BRICK STANDARD
      Clay bricks that are selected or produced for their durability and uniformity of size and shape.
   3. FBA - FACE BRICK AESTHETIC
      Clay bricks that are selected or produced for their durability and aesthetic effect deriving from non-uniformity of size, shape or colour
3. E - ENGINEERING UNITS
   Masonry units produced for structural or load-bearing purposes in face or non-face work, where the manufacturer suppliers clay bricks to an agreed compressive strength. An engineering unit is designated by the addition of the letter E followed by a number equal to the nominal compressive strength in megapascals eg FBSE21.
4. Paving
   1. PA - CLAY PAVERS (1:1, 2:1 or 3:1)
      Clay pavers that are selected or produced for their durability and for a high degree of uniformity in size and shape, and that have dimensions such that the ratio of work size length to work size is approximately 1:1, 2:1 or 3:1.
   2. PB - CLAY PAVERS
      Clay pavers that are selected or produced for their durability and for their uniformity in size and shape.