A life cycle of a construction project includes the planning and design phases that significantly impact the whole construction project. It has significant decisions like the outline of a building and selecting design alternatives in between the stages. Thus, the early design of preliminary estimates determines the feasibility of the project and total project cost. In the previous times, an estimation method demand time and its limited use resulted in several problems due to incomplete information, low data reliability and inaccuracy in estimates.
To resolve this problem, professional estimators start using the building information modeling (BIM) method. A BIM-based preliminary estimation method based on BIM models through which a quantity calculation is specific, and design progresses by posing limitations in support of the decision-making of the early design phase. It will eventually affect the construction cost and a particular cost incurred by the maintenance and dismantling of building structures.
What are Preliminary Estimates?
Preliminary estimates are briefly defined as the computation of the probable cost of a new development at some stages before the tender documents are produced. A preliminary estimating is a part of those estimation services that get prepared before the bill of quantities (BOQ) is available and when there is no bill of quantities for the project, their estimates arrive before the contract to obtain the tender sum.
A preliminary takeoff indicates the probable cost of construction. It is an essential factor to consider the client’s overall strategy of the decision to build, and its estimate will also deliver the basis for budgetary and control of the construction cost.
The anticipated cost varies slightly or efficiently, relying upon the availability of information regarding the project. It also assists the client/contractor to make the initial budget and cost control plan. It also depends upon the type of infrastructure. The estimation service involves different estimation techniques, and units vary differently.
For construction buildings:
It includes the rate per square foot/per cubic foot/per room/ per occupant is given.
For roads and highways
The rate per provided KM relies upon the thickness of layers and the types of construction material.
For Irrigation channels
The cost per given KM can also base on a per hectare basis.
Preliminary Cost Estimate
A preliminary cost estimate of a building relies on specific areas and length measurements of different structural elements. Moreover, the total square footage of a construction plot extracts the approximate cost for building the residential and commercial house, plaza or multiple story building. Many clients demand preliminary budget estimate specifically from the contractors, and it helps to extract an estimate of the total expenses for the completion of the project. It usually relies on the following services
- Total square footage of building
- Linear Measurements (walls etc.)
- Area measurements (rooms, floor, etc.)
It follows a comprehensive estimate that includes a list of all the construction materials with different specifications. It also contains a comprehensive BOQ (Bill of Quantities) on the cost of each particular line item that also includes masonry estimate and concrete estimate. Its total amount of budget for construction is precisely be estimated. A quantity takeoff sheet is priced efficiently by imposing the unit cost, and many clients demands cost filled BOQ’s from the contractors.
A preliminary and comprehensive estimation has many different purposes of use, required levels of accuracy and certain accepted levels of errors according to each phase. American Association of Cost Engineering (AACE) develops a cost estimate classification system. A preliminary estimation obtains at the initial stage of a construction project to establish the project budget and consider it an essential factor for the feasibility and alternative reviews of the project. It is difficult to estimate a construction cost accurately due to a lack of structured actual construction cost data. It is essential to construct a database for accurate estimates of the construction cost and reduce the frequency of rework to link information according to the project progress.
BIM-based Preliminary estimation
A BIM-based preliminary estimation carries different perspectives, and estimation methods include LCC rather than simple construction cost estimation, have been studied in late. The current BIM-based estimation method demands comprehensive modeling at a certain level because the accurate automatic calculation of quantity consider as a priority. It is difficult to estimate the BIM because design information is limited in the initial stage of the design, even if it is calculated through comprehensive and accurate modeling.
A piece of cost information is not accurate and consider the mistake to be made in the estimation. A standard cost or actual cost information is required to increase the accuracy of the cost information and view it as challenging to apply the standard cost model of the existing project. A performance cost is merely not limited to the collection of data because it is difficult to grasp the accuracy of the information. A preliminary budget estimation deals with the building’s material and construction costs.
Implementation of the BIM-based preliminary estimation system
A preliminary estimation system acquires the client’s requirement and relatively applies these to the BIM model. A generated model saves the repository server and data acquisition for the estimation and deliver the prototype system. A returned data and design alternative input data to quote through the database’s quotation algorithm.
Implementation of prototype system includes a preliminary estimation algorithm that defines the estimates to execute the basic information of the project and designer’s design alternatives. It also relies on the client’s requirements and the BIM model information. A designer selects the basic knowledge of the project and its alternatives are for each building site. A selected design contains links with the database to derive a similar sort of performance data. A derived data assigns the current value method to convert the past cost data to the current cost. An actual construction cost and standardized data to convert into LLC estimates.
Benefits of Preliminary Estimates
There are specific fundamental reasons due to which every client needs this initial estimate from the contractor. Following are the few significant benefits of having Preliminary Estimates
- Acquire a rough idea about total construction cost
- Assistance in quick planning and initial execution of the project
- Helps to manage the project budget and costs
- Allows the clients to opt for the best contractor
- Acquire information regarding the significant material required
Many professional estimating companies like World Estimating manage to deliver all kind of preliminary budget estimation, and the initial cost breaks down and material takeoff for construction and civil engineering projects.
They mainly offer our assistance to different owners and contractors who desire to know the estimated costs to complete the construction of the project. Their expert and well-experienced team manage to prepare all kinds of construction budgets, material takeoff services and construction estimates.