QUANTITY TAKE OFF-MEASUREMENT PRACTICE FOR EARTH WORKS,CONCRETE WORKS ,BRICK WORKS & PLASTERING

A Vision To Clear Solutions.

MEASUREMENT PRACTICE:

It is vitally important that measurement practice applied to buildings is both accurate and consistent. There are a number of situations that require a quantity surveyor to measure and record dimensions from both drawings as well as on site, depending on the stage of the project. In order to standardize measurement rules and conventions, there are a number of standard codes and methods of measurement that are available. These are outlined below.

There are various approaches to measurement for bills of quantities and these are as follows:

- Each (numbers): Piles, doors, Windows, Precast concrete, etc.
- Length (meter): Windows sills, Pipes, Skirts, stair steps, etc.
- Area (Square meter): Flooring, painting, plastering, Brick walls (12 cm or less), etc.
- Volume (Cubic meter): Brick walls (>12 cm thick), Excavation, Back filling, Reinforced Concrete, etc.
- Weight (Ton): Metallic works, Reinforcement steel, etc.
- Lump Sum: Some electrical and plumbing works, Manholes, etc.
- Effort (Man-day): Renting of equipment or labor, etc.


Figure 2.2 shows a sample of the quantity surveying table for quantity take-off.

PROJECT NAME:
PROJECT LOCATION:
S.NO	DESCRIPTION	UNIT	NO'S	LENGTH (metre)	BREADTH (metre)	DEPTH (metre)	QTY	TOTAL QTY	REMARKS
TOTAL QUANTITY

Earth works:
Earth works comprises site level, excavation, back filling and transportation of excavated materials.

Excavation:
- Quantities are calculated based on the dimensions of the foundation in plans from the owner perspective.
- Contractors should consider the excess of material excavated to all for safe operations.
- Prices differ based on the soil type, deep of excavation, ground water level, site location, shoring system, Equipment used, etc.
- Unit of measurement is cubic meter (volume).
- Consider the following example (Figure 2.3).

The length of excavation = 5.4 × 2 + (4.4 – 2) × 2 = 15.6 m

Depth of excavation = 1.8 m

Width of excavation = width of plain concrete footing = 1.0 m

Volume = 15.6 × 1.8 × 1.0 = 18.8 m3

- Consider another example (Figure 2.4). Plain concrete dimensions (1.2 × 2.0 × 0.2m), reinforced concrete footings dimensions (0.8 × 1.6 × 0.4 m); depth of excavation 1.2 m and ground beams cross section is (0.25 × 0.4 m). Find the volume of the excavated material (see Figure 2.4). Distance between center lines is 5 m.

Fig. 2.4: Footing foundation plan and cross section

Excavation for footings = 2 × 1.2 × 2.0 × 1.2 = 5.76 m3

Excavation for smell = (5 – 2 × 1) × 0.6 × 0.25 = 0.45 m3

Volume = 5.76 + 0.45 = 6.21 m3

Back filling:

- Unit of measurement is cubic meter (volume)

- Back filling = Excavation – volume of all works inside the excavated pit (footings,

smells, column necks, brickwork, etc.) + amount above GL (or – amount below GL) as shown in Figure 2.5.

Fig. 2.5: Back filling quantities calculations

- Consider the example shown in Figure 2.4, the volume of back filling could be calculated as follow:

Volume of backfilling = excavation – concrete – brick

Volume of concrete = 15.6 × 1 × 0.4 = 6.24 m3

Volume of brick = 15.6 × 0.4 × 1.4 = 8.736 m3

Volume of back filling = 18.8 – (6.24 + 8.736) = 3.824 m3

Site leveling:

- Measured in m2 (area) if thickness less than 30 cm.

- Measured in m3 (volume) if thickness more than 30 cm.

Soil transportation:

- Transported soil = vol. of exc. – vol. of back filling + additional soil at site

- Add swelling factor based on the soil type: 5% sandy soil. 15% clayey soil and 25% for demolition material. (owner or contractor)

Concrete works:

Concrete works comprises of both plain concrete (PC) and reinforced concrete (RC).

Plain concrete (PC):

- Measured in m2 (area) if thickness < 20 cm.

- Measured in m3 (volume) if thickness ≥ 20 cm.

- Average thickness should be mentioned when measurement is done by area.

Reinforced concrete (RC):

- All RC elements measured by volume (m3) except hollow block slabs measured by area (m2).

- Domes, cylindrical roofs and shells measured by area in the horizontal projection.

Brick works:

The rules and precautions that should be followed when measuring brick works are (Figure 2.6):

- Measured in m2 (by area) if thickness <25 cm.

- Measured m3 (by volume) if thickness ≥25cm.

- Deduct all openings.

- Deduct half the area (volume) of arches.

- Deduct all Concrete elements.

- Facades are measured by area.

- Separate item for each brick type

Plastering:

Plaster works are measured according to its location of being internal or external works.

Internal plaster work measured as it is (engineering measurement).

Internal Plaster:

- Engineering measurement by area (m2).

- All openings are deducted.

- All openings sides are added.

- Inclined slabs are calculated based on their horizontal projection.

External plaster:

- Measured by area (m2).

- Openings with areas < 4 m2 are kept with deduction.

- Deduct half the area of the openings ≥ 4 m2.

- Openings with areas < 4 m2 are kept with deduction.

- Cantilever slabs < 1 m projection not added.

- Add half the area of cantilever slabs ≥ 1 m.

If this article helped you then share with your friends through social networks below...