Lecture 1 (Introduction)

CEN 216

Quantity Surveying

What is Quantity Surveying?

• Quantity Surveying is the item-wise and sequential estimation of the quantity of different Engineering materials required for any kind of Civil Engineering construction work as well as their costing.

One of the dictionary meaning of the word “Surveying” is “Measuring”.

“Quantity Surveying” is the term adopted for measuring Quantities of a work based on standard method of measurement, in a systematic and scientific manner, which when priced will give the estimated cost of the work to a reasonable degree of accuracy.

Four distinct operations in

Quantity Surveying:1.Taking off or Measuring and

Recording Dimensions: process of measuring from drawings and recording all dimensions in a recognized form on specially ruled paper.

2.Squaring Dimensions: process of addition of the recorded dimensions to obtain linear, superficial or cubical measurement.

Four distinct operations in Quantity Surveying: (contd..)

3.Abstracting or Working up: process of collection of measurements of identical character under different trades and reducing them to units as required by the Standard Method of Measurement.

4.Billing: process of collecting and entering in the form of a bill of the work as separated into trades on the abstract. Unit prices are quoted against each item and the total value of Bill of Quantity (BoQ) of each trade is computed.

Role of a Good Quantity Surveyor:

• To look over the drawings and attempt to visualize the work. Attempt should not be made at the taking off, immediately on receipt of the drawings.

• To study the drawings carefully to see if the plans, elevations, sections etc are in agreement with one another.

• To check the dimensions with caution. If some dimensions do not exist in some places in the drawings, then it is always better to write them in. These missing dimensions should be worked out from other dimensions as far as possible, scaling from the drawing being the last option.

Role of a Good Quantity Surveyor: (Contd..)• To visit the site if possible. During his visit, he may collect valuable information like access to the site, nature of the surface soil, building to be demolished etc.

A quantity surveyor must have a sound knowledge of building materials and construction work. He must be accurate in his work and calculations.

Some important terms and their explanations:

• CC = Cement Concrete: plain concrete with no reinforcement

• RCC = Reinforced Cement Concrete: concrete with reinforcement

• LC = Lime Concrete: (lime + surkhi + khoa + water)

• GL = Ground Level: existing earth surface• PL = Plinth Level: the level of ground floor which is higher than the ground level to prevent entry of flood/rain water

• DPC = Damp Proof Course: provided in plinth level to prevent entry of moisture to the brick wall above. It is not provided in the veranda openings. DPC can be provided using 1:2:4 / 1:1.5:3 cement concrete or polythene sheets or bituminous carpeting.• FF = Floor Finish: a rich mixture of mortar with cement coating above provided at the floor level•BFS = Brick Flat Soling: usually one layer of dry brick or stone soling is applied below cement concrete. It is used in foundation and ground floor.• Setback: placing of a building at specified distance from road

•Skirting: an extended portion of floor finish provided in the brick wall so that any moisture can not enter into the wall when the floor is washed with water.

Skirting

•Lintel: a small beam provided over the openings like windows, doors or almirahs to support the brick wall. Generally 6” thick and width equal to wall width are provided.

Lintel

•Sunshade:

•provided in windows (at top level); built monolithically (integrally) with lintel to prevent entry of sunshine or rain water. •The thickness of wall end is 3” and at the free end thickness is 2”.•The projection of sunshades is extended 2’ from the face of wall.

•Drop Wall: provided in the verandah projected downward from the slab to prevent the entry of sunshine or rain water. Drop

wall

•Cornice: an extended portion of slab projecting horizontally outside from the slab protects the brick wall from sunshine or rain.

Cornice

•Parapet: a low wall or railing built along the edge of the roof.

Parapet

Components of Building

Roof

A Typical Wall Foundation

Remember the followings:• Nominal size of brick = 10” X 5” X 3” (with mortar) Actual size of brick = 9.5” X 4.5” X 2.75” (without mortar)• Excavation trench width is 6 inch greater than foundation width (3” on each side)• Inside plastering thickness = ¼ inch; mortar mix ratio= 1:6• Outside plastering thickness = ½ inch;mortar mix ratio = 1:4• Skirting: thickness = ¾ inch• 1 bag cement = 1.25 cft = 50 kg• Unit weight of Reinforced Cement Concrete = 150 lb/cft• Unit weight of mild steel = 490 lb/cft• The quantities of BFS, DPC, FF, plastering and pointing and painting are computed in square units.• The quantities of earthwork excavation, slab, beam, column, lintel are calculated in cubic units.