Storey Enclosure Method

Storey enclosure unit – It measure the area of external walls, floors and roof areas (effectively enclosing the building) and multiplying them by an appropriate weighting factor.

Not much used in practice and involves greater calculation.

Historical data are not readily available

Provides a single rate

Take into account of difference in plan shape total floor area, vertical position of the floors, overall height, storey height, extra costs of providing usable floor areas below ground.

1.  Floor areas, measured from the internal face of external walls and subject to the following  weightings

basements X 3

ground floor X 2

first floor X 2,15

second floor X 2.30 and add 0,15 for each successive floor

2. Roof areas are measured in its plan projection, to the extremities of eaves: roof x 1. 

3. External wall areas, measured on the external face of the walls:

 basement wall area      X 2    (basement floor to ground floor  level)

Above ground wall areas X 1  (ground floor to ceiling of top floor with no deduction for openings)

When this method was suggested, it aimed at  overcoming the problems detected in other single-rate estimating methods, by taking into account variations in plan shape and storey height. Unfortunately, the method was never totally adopted by construction professionals because it requires much more calculations than other single-rate methods and because the rates needed cannot be directly extracted from historical data

 Storey enclosure unit Method Estimate

Cube Method Estimating

The Cube method estimating is specific for building projects and aims to overcome the current criticism to the floor area method that does not take into account possible variations of  the storey height. The building volume method became very popular in some European  countries like in Germany and Switzerland, where building costs are often expressed in cubic  meter prices. The total cost of the project will be given by: 


Estimate = Volume X Unit Cost (Cost/m³)

External plan area X height X Cost (cost/ m³)

In order to use the method, the building volume must be first assessed and explicit rules exist  in some countries for that purpose. Buildings with distinct types of occupation should have  corresponding volumes assessed separately, for example, car park areas, shopping areas and  office areas in a commercial building. Specific works like excavations, foundations and  external works ought to be assessed separately by using cost comparisons or approximate quantities, for example. 


Costs per cubic meter may be difficult to find  in countries where the method is not current. Actually, such costs depend on a number of variables, like building types, proportion of wall  area per floor area, quality of finishes and so on.  

Calculation of volume is subject to rules of measurement

 >   Measured from external faces of external walls

 >  Height of the building is taken from the top of foundation to

     -          For pitched roof

      ·         A point midway between the ceiling and the apex of roof 2/3 where roof space is un-occupied

      ·         A point three quarters from the ceiling to the apex of the roof where roof space     is occupied

      -          For Flat roof

   ·         A point 610mm (2feet) above the roof structure                

Unit Method Estimating

Unit Method Estimating

The unit method estimating consists of choosing a standard unit of accomodation and multiplying  an approximate cost per unit

Estimate = Standard units of accommodation X Cost/Unit

for example:

Schools – costs per pupil place

Hospitals  - costs per bed place

Roads – per Kilometers

Car parks - costs per  car space

The technique is based on the fact that there is usually some close relationship between the cost of a construction project and the number of functional units it accomodates.  Functional units are those factors which express the intended  use of the building better than any other.  This method is extremely useful on occasions where the  building’s client requires a preliminary estimate based on little more information than the basic units of  accommodation.

The units adopted to facilitate this analysis depend on the  type of project under consideration.

Site condition

Specification changes

Market conditions

Regional changes

Inflation

Using this estimating method can generate a rough estimate quickly, but the lack of accuracy will render it of little use in the cost planning procedure outlined earlier. However, this method ids often used to determine the very first notion of a price in early discussions of a project and as a crude means of comparing the known costs of differet buildings.

Methods of Estimate

Methods of Estimating / Type of Construction Estimate

Methods of estimating,used in the early stages of cost planning,depend on reliablehistorical cost data whereas an analytical approach to estimating is based on applying current prices for resources to a well-developed design.A contractor may use a combination of estimating methods in developing a cost for a design and build project

1. Preliminary Estimate

Ø         ( i )  Single Rate Methods

·        Unit Method .......

·        Cube Method ......

·        Story Enclosure Unit Method

·        Superficial Area Method......

Ø         ( ii )  Later Stage Estimating ( Multi Rate Methods)

·        Approximate Estimating

·        Elemental Estimating

·        Cost Modeling

2. Engineering Estimate

3. Contractor detail estimate

·                    ·      Unit Quantity Method

·                    ·     Total Quantity Method

What are consider selection of equipment cost?

Equipment costs rank second to labor costs in term of uncertainty and in their effect on the outcome of anticipated profit for a construction project. Many factors can influence the selection of equipment in the construction project. These factors are considering equipment selection.

Task Consideration

Nature of work  This cost depends on the size of the job, the distance of transportation, and the means of transportation

Daily or hourly forecast of planned production

Distribution of work at site

Quality of work and tome allowed for completion

Interference expected and interdependence with other operation.

 Site condition:-  

Accessibility to location

Maneuverability at site

primary site condition factors are type of material to be handled. Physical constains onsite, and hauling distances.

The type and condition of the soil is important when choosing the most adequate equipment since each piece of equipment has different outputs for different soils. Moreover, one excavation pit could have different soils at different stratums.  Larger volumes of excavation will require larger excavators, or smaller excavators in greater number.

Equipment characteristics

Type of equipment considered suitable for the task.

Make, models and size of special purpose, and general purpose equipment available that can handle the task

Production capability, serviceability condition and delivery time of each equipment available.

Economic considerations

Owning costs.

Operating costs

Re-sale or residual value after use

Replacement costs of existing equipment

Commercial considerations

Buy second – hand or new equipment

Rent equipment

Hire- purchase equipment

Purchase on lease.

Single-rate approximate estimating

1.Unit of accommodation method
This method is commonly used by national bodies such as the education and
health services at the inception stage of construction.If a client has an amount of
money to spend (a budget) then it would be possible to consider the likely number
of functional units which can be provided.From experience,it might be found
that the cost of providing a study bedroom in student accommodation is £20000.
Using this figure an expenditure of £12 million would provide accommodation
for approximately 600 students.On the other hand if the number of units is
known,a budget cost (usually expressed as a cost range) can be calculated.
Providing there are recent comparable data available,the unit method is useful
where a simple and quick cost range is needed in the early stages.It is difficult,
however,to adjust the costs for specific projects,in different locations,with varying
ground conditions and so on.