Every construction company knows that building estimates are their lifeline. Any budget project plan has an impact on whether it will be successful. A more complex process with many variables is construction. The construction industry’s stakeholders face numerous difficulties in accurately estimating the project cost.
Building estimation is the realistic price of all construction-related activities and estimations, which is done by calculations based on the plans, item rates of work, and drawings.
Types of building estimates
Preliminary estimate
A commercial irrigation system or house generates revenue. In that case, the likely income can be evaluated, and the estimated price can be determined using a preliminary estimate. Next, the investment in the project is assessed to determine whether it is justified. Finally, contingencies are added at a rate of 5% to 10%.
Plinth area estimate
This estimate is a rough estimate that involves working out the plinth area of a structure and multiplying that by the plinth area rate to provide an estimate for that building. Then, using the building’s external dimensions at floor level, the plinth area for the covered area should be computed. Courtyards and other public spaces shouldn’t be a part of the plinth areas.
Approximate estimate
With this method, the running meter is used to roughly calculate the entire length of walls, and multiplying that total length by the rate of wall per running meter yields a pretty precise cost.
Cube rate estimate
This estimate is based on the planned building’s cubical content and applied at the rate per cubic content. Measure the length and width from the ground up to the roof peak.
Detailed estimate
A detailed estimate is a precise estimate that is generated in two estimates and includes calculating the quantities of each work item as the height of each item.
- Quantity measurement and calculation.
- Summary of the estimated cost.
Revised estimate
The revised estimate exceeds or is estimated to surpass by more than 5% of the sanctioned original estimate. Even though the approved amount might cover the cost, there has been a significant departure from the initial proposal.
Supplementary estimate
The supplementary estimate is created when additional work is needed to complete the initial works or when more development is required as the activity is being done.
Annual repair maintenance estimate
A thorough estimate for annual repairs or maintenance is created to keep the building or work in good order and a safe condition. Whitewashing, color washing, painting, little maintenance, and other such tasks are included in the building industry. Also possible are specific repair estimates, estimates for fixing monsoon damage, etc.
Work items in building estimates
Earthwork
The quantities of earthwork used in excavation and earthwork used in filling are often taken out separately under specific items and are estimated in cum.
The foundation Earthwork in an excavation is calculated by taking the dimensions of Breadth, Length, and Depth and applying the formula Length x Breadth x Depth.
Earth from excavations is used for plinth filling and backfilling.
Soling
The concrete foundation is filled with stone soling (40mm or 60mm aggregate) or one layer of dried brick when the soil underneath the structure is poor.
The thickness of the soiling layer is expressed in Sqm (breadth x length).
Masonry
Masonry calculations are made in Cum ( width x Length x thickness). Standard bricks of the sizes 9″ x 4.5″ x 3″ or 19mm x 9mm x 9mm are used in masonry.
It can also utilize lightweight bricks, concrete bricks, and other bricks. Each floor of a multi-story building, such as the first floor, second floor, etc., has its masonry calculation. Deductions are made for window and door openings, among other things, when calculating brickwork.
Concrete in foundation
The foundation concrete will have the same length and width as the excavation; the only difference will be in the thickness or depth. To estimate the amount of concrete needed for construction, multiply the dimensions by Cumulative. The typical concrete thickness is 30 cm. However, it can be anything from 20 to 45 cm. The foundation’s cement concrete ratio is either 1:4:8 or 1:5:10.
RCC work
The amounts for RCC activity are determined in Cum and may include work on beams, roofs, lintels, foundations, floor slabs, and columns. Building estimation uses Sqm measurements for centering and shuttering quantities. 0.6% to 1% of the RCC by volume are used for the steel calculation. Reinforcement is measured in MT (metric tones).
Damp proof course
A damp proof course is typically composed of permitted waterproofing material and is 1″ thick, 2 cm thick cement mortar 1:2, or 2.5 cm thick cement concrete 1:1.5:3.
Per bag of cement, one kg of Impermo, Cem-Seal, or another authorized waterproofing product is used.
The quantities are computed in square meters (Sqm), and this DPC is offered at plinth level over the entire width of the plinth wall (length x width).
At door sills and veranda openings, DPC is not offered.
Plastering
Thick 12 mm plastering is generally used for brick walls and is calculated in square meters (Sq.m.). Estimates are made for both sides of the walls, which are deemed to be of becoming solid.
Lintels over openings
Lintels are built using RCC and are estimated using Cum. If the bearing size is not supplied, it is assumed that the lintel has a minimum thickness of 12 cm.
The formula for lintel length is L=s + 2t, where s stands for clear span and t for bearing width.
L x the wall’s thickness x t equals the number of lintels.
Importance of building estimates in construction
The predicted expenses and time significantly impact the project’s success. As a result, it can be challenging to determine the value of development projects. Managing and forecasting building expenses can be significant when development projects have a strict schedule and financial constraints.
Construction estimating is also more difficult for mega-projects and large-scale civil works sponsored by public funding. A small error in the cost prediction process might significantly impact the physical building tactics. It is crucial to estimate the building costs for such a project accurately. It will improve your eligibility for large-scale projects and promote transparency throughout the process.
Factors for calculating building estimation
Area calculation
We determine the area for all 2D objects. There are two ways to do it: L*B (plasters, slab) or L*H (wall, plastering), with a square meter as the unit.
Volume calculation
We determine the volume of the 3D objects to assess them. Volume is utilized when there are three dimensions, with the unit being cubic meters, excluding all concrete and brickwork elements.
Enumerative quantity
These quantities can be counted; their numbers are determined per piece.
Mass
Steel, copper, aluminum, and brass are all metal-related commodities utilized in construction, and they are all measured in mass or kg. For this, we require knowledge of their volume and density.
Density=mass / volume
Mass=density * volume
Running meter
Consider a plumbing pipe with a 25 mm diameter. We define length as the distance between two points. Because only one dimension is present, m is used to measure it.
Factors for preparation of a detailed estimate
Availability of the materials
If the necessary materials are unavailable when needed, the predicted cost of the work will increase, and the workers and supervisory staff will be idle. As a result, the work will also be impacted. It should be assumed that the tools and equipment needed to complete the work will be on hand at the construction site as required.
Quantity of materials
It takes a lot of resources to create enormous works, but you can buy them for low cost than you would if you only needed a little bit. Therefore, the rate should be set based on the amount of effort.
Transportation of materials
Transporting fewer materials will cost more than transporting more materials purchased simultaneously.
Availability of labor
Before creating an estimate, it is advisable to take into account the daily wages of the local labor force and use as much local labor as feasible.
FAQs
What are the three categories of estimates?
Ballpark, budgeted, and definitive estimates are the three sorts of estimates that can be used to convey costs to clients.
What kind of estimate is the most accurate one for a building?
The plinth area estimate is the most accurate one for a building.
What is estimate accuracy?
The estimated accuracy measures how much the project's actual costs may differ from the single-point figure used to evaluate them.
What are the most problems with cost estimation?
Calculating financial effects Adjustments to the design Resource limitations Availability and quality of data Numerous groups are participating Consistency
