Good morning
SETTING OUT
After site clearing has been done setting out of foundation trench has to start.
Setting out is the process of transferring information for foundation walls and piers
from the drawing to the ground, but Datum peg has to be established before
setting out at site because this is the point where all levels at site are taken place.
Datum peg can either be concrete kerds, manhole cover, timber pegs etc. The
diagrams below shows how datum looks like.
SOME OF THE TOOLS/MATERIALS USED
DURING SETTING OUT OF A BUINDING ARE
Measuring tape =It is used for measuring dimensions.
Builder square =It is used for setting right angles in construction.
Spirit level = It is used for plumbing and levelling the building
Brick trowel= It is used for carrying and spreading mortar
Builder line =used for transferring of information from one corner profile to the
other.
Straight edge
Nails =
Hand saw = Are used for marking width of trenches and wall on profiles.
Timbers = are used as profiles and pegs during setting out.
CONSTRUCTION AND POSITION PROFILES
Profile boards indicate the position of walls and foundation. Ranging lines are
located on to the profiles, which trace out the alignment of walls and foundations.
The overall walls and width of foundation trenches are shown on the profile boards
below. The main function of profile boards is to keep or store information for the
building.
There are two types of timber profiles.
1. Return profile containing three pegs and two profile boards.
This type of profile is mostly used in corners or right angles and it is shown in figure
below.
2. Single profile containing two pegs and one profile board it is mainly used when demarcating
partitions or rooms when building the house. The figure below shows how it looks like.
FUNCTION OF PEGS
To establish the corner point of the building.
To support the profile boards.
To establish the level of concrete in the foundation.
Used as a datum pegs.
Setting out of the house can be done either by using builders square or 3:4:5 or 6:8:10
method and these two methods can also be used to obtain 90°. See the figure below
The squareness of a building can be checked by using diagonal checking method .
But the following methods can be used for obtaining right angle of the building at a
building site.
Using builders square
Using 3:4:5 or 6:8:10 method
After setting out has been done transferring of information from the ranging lines to
the ground has to take place. This activity can be done by using straight edge
inconjuction with spirit level, where by brick trowel can be used for marking on the
ground.
Marking of lines position on the ground can be done by using sharp objects, sand
lime and a hoe hence digging of foundation can start. Foundations can be dug
by manually/Hand method
ADVANTAGES OF MANUAIIY/HAND METHOD WHEN DIGGING FOUNDATION
The work is done 100% accurate
It does not need skilled people to dig the foundation
Tools for digging the foundation are locally found.
It is cheap method for digging the foundation since labour is abundant.
DISAVANTAGES OF HAND METHOD
It is tiresome method for digging the foundation
The work is not done in intended time hence it delays the work
More labour is required to complete the work
USING MACHINE METHOLD FOR DIGGING FOUNDATION
The figures shown below are some of the plants/equipment’s used for site clearing on
a building site.
ADVANTAGES
The work is done very fast.
It does not need more labour to do the job in terms of people to be employed.
It is not tiresome method for digging the foundation.
DISAVANTAGES
It is very expensive to maintain the machine.
It needs skilled people to operate the machine.
Labour is not abundant.
It is also expensive to hire the machine.
There are many different types of soil suitable for building on. Each type
has its own characteristics and properties and these are;
Rock soil
Granular soil
Cohesive soils
See the types of soil and bearing capacity in the table 1 below.
GROUP TYPES OF SOIL SUITABLE FOR BUILDING ON BEARING CAPACITY
Rock soil Granite 650KN/m2 and upwards
Limestone
Sandstone
Slate
Shale
Hard solid chalk
Non-cohesive or granular Compact well-graded sands. Gravel sand. From 100KN/m2 to 650KN/m2 in their
soils Mixtures. Loose well graded sand. Compact dry state (Dry in this case means
uniform sands. Loose uniform sands that the foundation width below the
base of the foundation)
From 50KN/m2 to 300KN/m2 in a wet
state.
Cohesive soils. Stiff boulder clays. Stiff clays sandy clays. Firm From 50KN/m2 to 650KN/m2
clays. Soft clays. Sandy silts. Very soft clays
and silts.
ANY QUESTION
BYE
