2.5.2.1 Types of Walls

Wall can be divided into the fallowing types:

• Load bearing external wall

• No-load bearing external wall

• Load bearing internal wall

• No-load bearing internal wall

2.5.2.2 Building Materials for Wall

• Natural stone

• Bricks

• Cement based block

• Reinforced concrete

• Cladding sheets (non load bearing external wall)

2.5.2.3 Wall Characteristics

• External walls should have these characteristic:

• Strength

• Stability

• Weather resistances

• Durability

• Adequate fire resistance

• Openings for day light and ventilation

Internal wall have these characteristics:

• Position that provide separation between rooms

• Sound insulation that provide a reasonable level of noise control between adjoining rooms

• Stability

• Durability

• Fire resistance

2.5.3 Column

A column is defined as a member carrying direct axial load which causes compressive stress of such magnitude, column or strut is a compression member and the effective length of which should be at least exceed three times the least lateral dimension

2.5.3.1 Types of Column

The columns are into two types:

• Short column

• Long column

Short Column

When the ratio of the effective length of column to it’s least lateral dimension does not exceed:

14.3: for rectangular shapes

12.4: for circular shapes

12.7: for octagonal shapes

Is termed “Short Column”

Long Column

A long column is the ratio of effective length to its lateral dimension exceeds:

14.3: rectangular shapes

12.4:for circular shapes

12.7:for octagonal shapes

Is termed “Long Column”

2.5.3.2 Failure of Column

If the force or load is gradually increased the column will reach a stage, when it will subjected the ultimate crashing or buckling stresses, beyond this stage the columns will failure by crushing or buckling

Crushing: is the mode of failure for the short column and this increase cracks

Buckling: is the mode of failure of long column(bending)

2.5.4 Lintels

Definition: a lintel is a structure that spans a cross a horizontal openings and support

Loads just above the openings

2.5.4.1 Lintel Materials

The lintel can be timber or concrete and timber is fine for short spans but is not durable, for this reason most lintel are build in reinforced concrete.

2.5.4.2 Constructing Concrete Lintel

The structure engineer design lintels for large building, but you can follow the basic guide lines when construct lintel for domestic scale construction.

The table bellow show the standard dimensions for lintels

Span	Depth	Reinforced bar diameter
900mm 1200mm 1500mm 1800mm	150mm 150mm 215mm 215mm	10mm 12mm 12mm 16mm

Table 1. Standard dimensions for lintels

• Casting concrete lintels

After designing, lintels should be cast, the lintel can be cast in situ or precast. The span will determine the height of the lintel which should correspond to the height of full bricks courses

• Precast: is the process of making lintels separately from the building and the advantage is that the lintel can be placed in position as so an as the brick work is ready.

• In Situ: is the process of pouring the concrete into the formwork across the opening to make the lintel and we follow those three procedures:

1. Put the timber formwork across the opening

2. Place the reinforcement bars

3. Pouring the concrete

N.B: after the concrete harden, you remove the formwork this method increases the labours element of the job and may flow down the brick laying or concrete walls materials.