METHOD OF BUILDING ESTIMATE

 

                                           METHODS OF BUILDING ESTIMATE

The dimensions, length, bread the and height or depth are to be taken out from the drawing plan,   elevation and section. From the study of the drawings, the building is to be imagined and pictured in    the mind and the dimensions are to be taken out correctly. There is no hard and fast rule for finding out       dimensions from the drawing but the dimensions are to be taken out accurately.

Junctions of wall at the corners and at the meeting points of walls require special attention.

For symmetrical foundation which is the usual case, earthwork in excavation in foundation, foundation concrete, brickwork in foundation and plinth, and brickwork in superstructure may be estimated by either of the following two methods.

 

1.       -       Separate wall or individual wall Method
2.               Centre line Method

 

METHOD I

Separate or individual wall method.

 In this method, measure or find out the external length of walls running in the longitudinal direction generally the long walls out-to-out, and the internal lengths of walls running in the transverse direction in-to-in i.e. of cross or short walls in-to-in, and calculate quantities multiplying the length by the breadth and the height of wall. The same rule applies to the excavation in foundation, to concrete in foundation and to masonry. Care should be taken to note the difference in dimensions at different height due to offset, or footings. It is convenient to imagine plans at different level of heights as foundation trench plan, foundation concrete plans of each footing. Etc. and dealing each plan or part separately.

 

The simple method is to take the long walls and short or cross walls separately and to find the centre to centre lengths of long walls and short walls from the plan. For symmetrical footing. either sides, the centre line remains same for superstructure and for foundation and plinth

For long walls add to the centre length one bread th of wall, which gives the length of the wall out-to-out, multiply this length by the breadth and the height and get the quantities. Thus for finding the quantities of earthwork in excavation, for length of the trench out-to-out add to the centre length one breadth of foundation. Adopt the same process for foundation concrete, and for each footing. It should be noted that each footing is to be taken separately and the breadth of the particular footing is to be added to the centre length.

(Long wall length out-to-out = centre to centre length + half breadth on one side + half breadth on the other side = centre to centre length + one breadth).

For short or cross walls subtract (instead of adding) from the centre length one breadth of wall which gives the length in-to-in, and repeat the same process as for the long walls, subtracting one breadth instead of adding. (Short wall length in-to-in F centre to centre length one breadth).

That is, in case of long wall add one breadth and in case of short wall subtract one breadth from the centre length to get the corresponding lengths.

METHOD II

Centre Line Method.

in this method known as centre line method sum-total length of cent. lines of walls, long and short, has to be found out. Find the total length of centre lines of walls, of same type, long and short having same type of foundations and footings and then find them. Quantities by multiplying the total centre length by the respective breadth and the height. In this method, the length will remain same for excavation in foundation, tor concrete in foundation. For all footings and for superstructure (with slight difference when there are cross walls or number of junctions). This method is quick but requires special attention and consideration at the junctions, · meeting points of partition or cross walls, etc.

For rectangular, circular polygonal (hexagonal, octagonal, etc.) buildings having no inters or cross walls, this method is quite simple. For buildings having cross or partition walls, for every junction of partition or cross walls with main walls, special consideration shall have to be made to find the correct quantity. For each junction half breadth of the respective item or footing is to be deducted from the total centre length. Thus in the case of a building with one partition wall or cross wall having two junctions, for earthwork in foundation trench and foundation concrete deduct one breadth of trench or concrete from the total centre length (half breadth for one junction and one breadth (2x½= one for two junctions). For footings, similar deduct one breadth of footing for two junctions from the total centre length, and so on. If two walls come from opposite directions and meet a wall at the same point, then there Will be two junctions.

For building having different types of walls, each set of walls shall have to be dealt separately.

Find the total centre length of all walls of one type and proceed in the same manner as described above. Similarly find the total centre length of walls of second type and deal this separately, and so On.

In the case of a building having different type of walls, suppose the outer (main) walls are of A type and inter cross walls are of B type, then all A type walls shall be taken jointly first, and then all

B type walls shall be taken together separately. In such cases no deduction of any kind need be made for A type walls, but when B type walls are taken, for each junction deduction of half breadth of A type wall (main wall) shall have to be made from the total centre length of walls.

It may be noted that at corners of the building where two walls are meeting no subtraction or addition is required.

When there are number of footings, the length of the first footing is to be determined by deducting half breadth of footing per junction from the total centre line length and then the length of the subsequent footing can be obtained simply by adding one offset of footing i.e. 5 cm for every junction to the length of the previous footing