Quantity Surveying Interview Questions and Answers – 1

Quantity Surveying is the process of calculating the quantities and costs of the various items required in connection with the work. To prepare and estimate, drawings consisting plan, the elevation and the sections through important points, along with a detailed specification giving specific description of all workmanship, properties and proportion of materials, are required.

1. Preliminary estimate or Rough cost estimate
2. Plinth area estimate
3. Cube rate estimate or cubical content estimate
4. Approximate quantity method estimate
5. Detailed estimate or item rate estimate
6. Revised estimate
7. Supplementary estimate and revised estimate
8. Annual repair or maintenance estimate
9. Supplementary estimate

This is prepared on the basis of plinth area of building, the rate being deducted from the cost of similar building having similar specification, heights and construction, in the locality. Plinth are estimate is calculated by finding the plinth area of the building and multiply by the plinth area rate. Plinth are estimate is only approximate estimate.

The accuracy to be observed in preparing an estimate depends on the rate of the item and the unit of payment. The higher the rate the greater should be the accuracy with which the quantities are calculated. Where rates are high and paid per unit may be allowed for practical purpose, the quantities in such should be worked out to at least two places of decimal.

Revised Estimate is the detailed estimate and is required to be prepared under the following circumstances:

When the original approved estimate is exceeded of likely to exceed by more than 5%.

When the expenses on a project exceeded or likely to exceed the amount of administrative sanction by more than 10%.

When there are material deviations from the original proposal, even though the cost may be met from the sanctioned amount.

• Segmental arch with span and angle
• Segmental arch of 60⁰
• Segmental arch with span and rise
• Semi-circular arches
• Flat arches

Load Bearing Structures

Load bearing structures are structures where the load are transferred to the foundation via load bearing walls (external and internal). These types of structures have a smaller window to walls ratio. Since the loads are borne by the walls the height of the walls are limited.

Framed Structures

Framed structures are structures where the loads are transferred to the foundation via beams and columns. The load in floor is transferred to the beams and then columns. These type structures can have large open areas in the walls. These types of structures can be adapted in high-rise buildings.

Lintel                     –              0.7 to 1.0%

Column                –              1.0 to 5.0%

Beam                    –              1.0 to 2.0%

Footing                 –              0.5 to 0.8%

• Preliminary Estimate or Rough cost estimate
• Plinth area method
• Cube rate Estimate or cubical content estimate
• Approximate Quantity Method Estimate

Plinth area is the area of a building measured at floor level. It is measured by taking external dimensions excluding plinth offset if any.

Carpet area is the area in building which is useful i.e., area of drawing room, dining room, bed room etc. Areas of kitchens, staircase, stores, verandas, entrance hall, bathroom, basement etc., are excluded. It is generally 50% to 60% of the plinth area.

Painting of doors and windows shall be measured closed and flat not girthed in sq.m and shall include chaukhat edges, cleats, etc. different types of doors and windows are battened, panelled, glazed etc., shall be covered into equivalent plain area by multiplying the flat area by a multiply factor or coefficients.

Damp proof course (DPC) is a barrier provide in construction at plinth level to prevent water or moisture to rise by capillary action and make safe the floors and walls by the problem of dampness. DPC is usually of 2.5 cm thick rich cement concrete mixed with water proof material. It is computed in sq.m.

Detailed estimate is an accurate and provide comprehensive information about the project. It includes the quantities and cost of everything required for satisfactory completion of work and this is the most reliable and best estimate.

It is defined as incidental expenses of miscellaneous character which cannot be classified approximately under any distinct subhead, but is added in the cost of construction necessarily. It is generally 5% of the estimate and added as contingencies and petty works, e.g. purchase of tools or medicines for labour etc.

Approximate estimate is required for preliminary studies of various aspects of a work or project, to decide the financial position and policy for administrative sanction by the competent administrative authority. In case of commercial projects which earn revenue income, the probable income may be worked out, and from the preliminary estimate the approximate cost may be known and then it may be seen whether the investment, on the project is justified or not.

Plinth area estimate is calculated by finding the plinth area of the building and multiplying by the plinth area rate. Court yard and other open areas should not be included in the plinth area. This estimate is prepared on the basis of plinth area of building, the rate being deducted from the cost of similar building having similar specification, height and construction, in the locality.

In centre line method, total centre line length of walls in a building is calculated and multiply the same by the breadth and depth of the respective item to get the total quantity at a time.

Following factors are most importantly need to be considered:

• Quantity of materials
• Availability of materials
• Transportation of materials
• Location of site
• Local labour charges

In this method, all costs of a unit quantity such as per k.m. for a highway, per metre of span for a bridge, per classroom for school building, per bed for hospital etc. are considered first and the estimate is prepared by multiplying the cost per corresponding unit by a number of units in the structure.