Draw
the sketch and explain with taking out dimensions, the centre line method of
taking out quantities.
Ans.
Sketch of a single room
building is shown.
In the method of “Centre line
method” given by total length of centre lines of walls, long and short is
joined int. Total quantities one formed by multiplying the total centre length
by the respective width and height. In this method the length will remain same
for excavation in foundation for concrete in foundation, for all footings and
for super structure (with slight difference when there are cross walls or no.
of junctions).
The above sketch is re-written,
which represents the foundation trench plan.
By centre line method, the
total length of walls
= AB + BC + CD + DA
= 5.3 + 4.3 + 3.3 + 4.3
= 19.20 m.
If the total centre length is
multiplied by the breadth and depth we get the quantity of earth work in
excavation by do so, we take centre portion twice and leave an equal portions
but this does not effect the quantity.
The quantity of excavation –
AB x 90 cm x 90 cm + BC x 90 cm
x 90 cm
CD x 90 cm x 90 cm + DA x 90 cm
x 90 cm
It may be noticed that the
portions P,QR,S marked with double hatch lines come twice while the portions
K,L,M,N left blank do not come at all, but these portions being equal in magnitude,
we get the quantity correctly.
The same principle applies to
formation concrete, footings, plinth wall and super structure.
Mention
how and where you will amount for the following in the estimate –
Salary of the watchman.
Dewatering from foundation
trenches.
Ans.
Salary
of the watchman
This is amounted in
“Work-charged Establishment”, which is charged to work directly. A percentage
of 1 ½ to 2% of the estimated cost is provided for this so as to avoid any
excess over the administratively approved estimate. The salary of watchman and
of similar persons such as mates, who are employed on purely temporary basis is
paid from this provision in the estimate.
Dewatering
from foundation trenches
This is amounted as
contingency. It indicates the incidental expenses of miscellaneous character
which cannot be classified under any distinct item, get pertains to the work
and a whole.
A provision of 3 to 5% of the
estimated cost is provided in the estimate to meet the cost of unforeseen
items, as for the expenses of miscellaneous nature which do not fall under any
sub head of item or work.
Mention
the data which is required for preparing detailed estimate.
Ans.
Drawings
:
complete and fully diamentions drawings (i.e plans, elevation, section and
other details) of the work in question and required.
Specifications
:
Detailed specifications, giving the nature, quantity and class of work,
materials to be used in the various parts of work, quantity of the material,
their proportions, methods of preparation, workmanship and description of
execution of work are required.
Rates
:
The rates of various item of work, materials to be used in the construction,
and the working different categories of labour, should be available for
preparing an detailed estimate. The cost of transportation should also be known. As far as possible sanctioned
“Schedule of rates” shall be followed or the rates may be worked out by the
“Analysis of Rates” method.
State
the unity of measurements of the following
Form work for casting RCC Beam
Steel reinforcement.
Ans.
Form
work for casting RCC Beam
Form work for casting RCC Beam
– sq.m.
Steel reinforcement – Quintal
Rules
for deduction in masonry work
No deduction or addition shall
be made for the following.
Ends of dissimilar materials
(that is joists, beams, lintels, posts, girders, rafters, purlines, trusses,
corbels, steps, etc.) upto 0.1 m2 in section.
Opening upto 0.1 m2
in areas (In calculating the area of opening, any seperate lintel (or sill)
shall be included but the end portions of lintels etc., shall be execluded.
