Setting out of
Foundations
Foundations
Before Commencement, of the excavation of trenches for foundation,
a setting out plan is prepared on paper. The setting out plan
is a dimensioned ground floor plan, usually drawn to scale of 1:50. The plan is
fully dimensioned at all breaks and openings. One of the methods of setting
out of foundations is to first mark the centre line of the longest
outer wall of building by stretching a string between wooden pegs driven at its
ends. This serves as the reference line for marking the centre line of all the
walls of the building. The centre line of the wall, which is perpendicular to
the long wall, is marked by setting up a right angle. Right angle is set up by
forming triangles with sides 3,4and5units long. If we fix the two sides of the
right angles triangle to be 3 m, and 4 m, then the third side i.e. the
hypotenuse should be taken a 5 m. The dimensions should be set out with a steel
tape. The alternative method of setting out right angle is by the use of
theodolite. This instrument is also helpful in setting out acute or obtuse
angles. Small right-angled Projections are usually set out with mason’s square.
a setting out plan is prepared on paper. The setting out plan
is a dimensioned ground floor plan, usually drawn to scale of 1:50. The plan is
fully dimensioned at all breaks and openings. One of the methods of setting
out of foundations is to first mark the centre line of the longest
outer wall of building by stretching a string between wooden pegs driven at its
ends. This serves as the reference line for marking the centre line of all the
walls of the building. The centre line of the wall, which is perpendicular to
the long wall, is marked by setting up a right angle. Right angle is set up by
forming triangles with sides 3,4and5units long. If we fix the two sides of the
right angles triangle to be 3 m, and 4 m, then the third side i.e. the
hypotenuse should be taken a 5 m. The dimensions should be set out with a steel
tape. The alternative method of setting out right angle is by the use of
theodolite. This instrument is also helpful in setting out acute or obtuse
angles. Small right-angled Projections are usually set out with mason’s square.
The method of Setting out of Foundations described
above is not so reliable for important works as there is likelihood
of the wooden pegs being pulled up or displaced. In an accurate method, the
centre lines of the building walls arc carefully laid by means of small nails
fixed into the head of the wooden pegs driven at the quoins. In case of
rectangular buildings, the diagonal from the opposite corners are checked for
their equality. Small brick walls, pillars or platforms are constructed 9ocm
clear of the proposed foundation trench. The platforms are about 15 cm wider
than the trench width and are plastered at top. The tops of all platforms or
pillars should be at the same level preferably at plinth or floor level of
building. The strings are then strenched over the nails in the pegs and the
corresponding lines are marked on the wet plastered platforms top by pressing
the stretched string on the plastered surface by a trowel. The outside lines of
thefoundation trench and the plinth lines are marked on the wet
plastered platform top in the similar manner.
above is not so reliable for important works as there is likelihood
of the wooden pegs being pulled up or displaced. In an accurate method, the
centre lines of the building walls arc carefully laid by means of small nails
fixed into the head of the wooden pegs driven at the quoins. In case of
rectangular buildings, the diagonal from the opposite corners are checked for
their equality. Small brick walls, pillars or platforms are constructed 9ocm
clear of the proposed foundation trench. The platforms are about 15 cm wider
than the trench width and are plastered at top. The tops of all platforms or
pillars should be at the same level preferably at plinth or floor level of
building. The strings are then strenched over the nails in the pegs and the
corresponding lines are marked on the wet plastered platforms top by pressing
the stretched string on the plastered surface by a trowel. The outside lines of
thefoundation trench and the plinth lines are marked on the wet
plastered platform top in the similar manner.
Before starting
excavation, the strings are stretched between the outside lines of thefoundation trench
marked over the platform top and the cutting lines are marked on the ground by
lime powder. If necessary, the lines may be marked by a daghbel or pick-axe.
excavation, the strings are stretched between the outside lines of thefoundation trench
marked over the platform top and the cutting lines are marked on the ground by
lime powder. If necessary, the lines may be marked by a daghbel or pick-axe.
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