BT4: QUANTITY SURVEYING AND COST ESTIMATING PT. 1

Estimate

Approximation, projection or prediction of a quantity of work; a statement of the approximate or projected cost of work to be done, such a building or any other project that entails material, labor and services costs; a general calculation of size, value, magnitude, extent of work to be done including materials, labor and other parameters that require quantification.

Quantity Survey

A term describing the detailed calculation of all components necessary to construct a building generated by quantity of materials, labor and other parameters; a detailed analysis and listing of all items of materials and equipment necessary to construct and complete a project.

Detailed Estimate of Construction Cost

A forecast of construction cost prepared on the basis of a detailed analysis of materials and labor for all items of work, as contrasted with an estimate based on current area, volume, or similar unit costs.

Bill of Materials

A term used to describe the materials, subcomponents needed to manufacture a finished product.

User-unit Method

[estimating methods] This estimating method involves the determination of user or occupants to quantify space and to establish cost, e.g. number of students, patient beds, inmates, etc.

Area Method

[estimating methods] involves costing and quantification using area and multiplier or factor. This method is commonly used to provide a rough estimate of project cost by multiplying area by cost per unit area (usually square meter) based on prevailing rate.

Volume Method

[estimating methods] This method involves a three-dimensional aspect of the project. Such method is an extension of the area method but involves the height of the building project as height affects cost of the project. In most cases the area method is generally used when estimating small to medium project since it involve a standard height and deviation may be considered minimal.

Parametric Method

[estimating methods] involves the identification of several major factors in estimating such as architectural, structural, electrical, plumbing/ sanitary, mechanical, etc. components of the project each with a corresponding percentage cost.

Modular Cost Method

[estimating methods] estimates applies to repetitive work or work made of similar components or project composition such as apartment, housing units or hospital room units where cost can be calculated based on the cost per unit, the total cost of the project can be calculated by multiplying the unit cost and the number of units.

Detailed Estimate by Quantity Take-off Method

[estimating methods] (Quantity Survey) This method is considered as the most precise of the different types of estimating method. Materials are quantified base on specifications type, composition, application, commercial sizes

and other parameters.

Combination Method

[estimating methods] This method may be used although not that accurate if the project and the scope of work is incomplete or some areas of the project are not clearly defined, hence, a combination of different methods becomes practicable.

Earthwork

consists of excavation, filling/backfilling

Concrete work

consists of Cement, Sand and Gravel Estimating Factors

25

The additional ___% of excavation

volume accounts for earth volume increase resulting from excavation (disintegration of earth)

25

The additional ___% of excavation

volume accounts for volume increase due to loose volume of earth for filling/backfilling

AA

[concrete] class:____

1 : 1.5 : 3

A

[concrete] class:____

1 : 2 : 4

B

[concrete] class:____

1 : 2.5 : 5

C

[concrete] class:____

1 : 3 : 6

D

[concrete] class:____

1 : 3.5 : 7

Special

[concrete] class:____

1 : 2 : 3

Mortar

[concrete] class:____

1:2 or 1:3

40 kg

A bag of Portland cement weighs ____ (local commercial weigh per bag of cement)

1,600 kg

A cubic meter of sand (dry) weighs ___

1,442 kg

A cubic meter of sand (loose) weighs ___

1,520 kg

A cubic meter of gravel (loose, dry) weighs ____

50

A bag of cement can produce ___ pcs - 6" CHB using a ratio of 1:5, 1 bag of cement per 5 bags of sand.

350

Compressive strength of CHB is ___ psi (non-load bearing block).

750

Compressive strength for load-bearing block is ___ psi, cement-to-sand ratio is reduced.

12.5

How many pieces of CHB per square meter?

A

[chb mortar/filler/plaster micture]

class ___

mixture - 1:2

cement - 18 bags

B

[chb mortar/filler/plaster micture]

class ___

mixture - 1:3

cement - 12 bags

C

[chb mortar/filler/plaster micture]

class ___

mixture - 1:4

cement - 9 bags

D

[chb mortar/filler/plaster micture]

class ___

mixture - 1:5

cement - 7.5 bags

1:4

[chb mortar/filler/plaster micture]

cement-sand ratio

0.8 sqm

[chb mortar/filler/plaster micture]

face area per block

0.5 sqm

Commercial volume (m3) or quantity of construction materials such as sand and gravel are, practical reasons, usually measured in volumes ___

125, 50

[Recommended Slumps] (ans: max, min)

Reinforced foundation wall and footing

100, 25

[Recommended Slumps] (ans: max, min)

Plain footing, caissons and substructure

walls

150, 75

[Recommended Slumps] (ans: max, min)

Slabs, beams and reinforced walls; columns

75, 50

[Recommended Slumps] (ans: max, min)

Pavement

75, 25

[Recommended Slumps] (ans: max, min)

Heavy mass construction

4db

[standard hooks] 180˚ bend plus ____ extension, but not less than 65 mm at free

end of bar

12db

[standard hooks] 90˚ bend plus ____ extension, at free end of bar

16 mm and smaller

[stirrups/tie hooks] 90˚ plus 6db extension at free end of bar

20 mm and 25 mm

[stirrups/tie hooks] 90˚ plus 12db extension at free end of bar

25 mm bar and smaller

[stirrups/tie hooks] 135˚ bend plus 6db extension at free end of bar

6db

[minimum diameters of bend] 10 mm to 25 mm

8db

[minimum diameters of bend] 28 mm and 32 mm

10db

[minimum diameters of bend] 36 mm