Apr 14

Elemental Method of Estimating – Advantages and Disadvantages [Building Construction]

House Under Construction Walls and Roof

 

When compared to the Unit and Superficial Area method, the Elemental Estimate or elemental method of estimating is a more detailed method of calculating the cost of a construction project. This estimate is easily understood by the client or any party involved in the design consultation because it shows separate elements of the building that have to be priced. It is good for cost planning (budgeting) because the summary shows the cost of each element. Just by looking at the summary, the Quantity Surveyor can identify elements which are taking up too much cost, and an investigation can be launched. This is done by analyzing the elemental items, for example the type of floor finishes used in the building. If the floor finishes are too expensive, alternative materials should be suggested by the Architect. The aim is to allocate money on essential components of the building first, and non-essential parts afterwards.

If you want to get useful information from an Elemental Estimate for cost advice purposes, then you should use an estimating program like QSPlus. QSPlus has a specialized Elemental Estimating module that shows you the percentage of the total cost for each element as well as the cost per m2.

Layout of an Elemental Estimate

Depending on the scope of your building project and specifications, an Elemental Analysis (Summary) will have the following elements:

Element Unit Quantity Unit Rate Cost Cost/m2 Percentage of Total Cost
1 Foundations M2
2 Ground Floor Construction M2
3 Structural Frame M2
4 External Envelope M2
5 Roofs M2
6 Internal Divisions M2
7 Floor Finishes M2
8 Internal Wall Finishes M2
9 Ceilings and Soffits M2
10 Fittings M2
11 Electrical Installation M2
12 Internal Plumbing No.
13 Fire Services No.
14 Balustrading, Etc. m
15 Air Conditioning M2
16 Soil Drainage m
17 Water Supplies m
18 Connection Fees, Etc No.
19 Boundary, Screen and Retaining Walls, Etc. M2
20 Roads, Paving, Etc. M2
21 Preliminaries M2
22 Building Contract Contingencies M2
23 Cost Per M2 of Construction Area M2         100%
24

 

Each element is made up of component items and details which are not shown above. If you are preparing your estimate using computer estimating software like QSPlus, you should be able to drill down (click through) to the component details. As an example, the element Foundations should have the following component items:

 

 

Unit Quantity Unit Rate Cost/m2 Subtotal Cost
FOUNDATIONS

 

Unreinforced Strip Footings:
Mass concrete footing 600x300mm, excavation 1m deep, risk of collapse, compaction, backfilling, blinding and ant proofing etc.

 

m 45 200
Mass concrete footing 700x300mm, excavation 1m deep, risk of collapse, compaction, backfilling, blinding and ant proofing etc.

 

m 210 250
Brick and Block Walls:

 

One brickwall in foundations 1m high, finishes, including reinforcement and DPC.

 

m 210 250
Half brickwall in foundations 1m high, finishes, including reinforcement and DPC.

 

m 45 130
Subtotal FOUNDATIONS M2

 

The primary component items in an Elemental Estimate are actually Bill of Quantity items. Estimating software like QSPlus allows you to add primary BOQ items from a Library or existing project. By the click of a button, you can add selected items from a past project to create your element. However, the units of measurement used in an Elemental Estimate are different from those used in a BOQ.

In an Elemental Estimate, all the items associated with a primary item are measured at once using the primary item unit. In the above example, there are two primary items Unreinforced Strip Footings and Brick/Block Walls. Under Strip Footings, the items associated with this primary item are mass concrete footings, excavation, risk of collapse, compaction, backfilling, blinding and ant proofing. The unit of measurement for this group of items is the metre (m). When taking off quantities from a design plan, the Estimator only needs to measure the length of strip footings (the external perimeter of brickwalls is used in this case).

Grouping items in Elemental format allows the Estimator to measure quantities and produce the project cost much faster than detailed Bills of Quantities.

An elemental estimate can be finished within a day or two if rate build-up is not needed, but a detailed BOQ takes weeks to complete.

When To Use Elemental Method?

This type of estimate is best used for comparing design alternatives produced by the architect. It is essential when the client has a budget and wants to choose the most economic design that won’t stretch the initial budget. If you need an estimate for securing finance or presentation purposes, for example presenting your building plans to a potential investor, financier or sponsor, an elemental estimate is the best estimate that would impress the financier, because it shows detailed costing of building elements.

With an elemental cost plan, the Quantity Surveyor can keep a check on costs during the designing stage prior to preparing Bills of Quantities. If the client has a specific budget in mind, the architect’s specifications will need to be adjusted to match the client’s budget.

A lot of adjustments will be required by both the architect and quantity surveyor in the planning stage. For the architect, this involves a lot of redrawing and for the QS, this involves adjusting cost items in the estimate.

Advantages of Elemental Method of Estimating

  1. An elemental cost analysis is easy to understand .It makes sense to people involved in the project because it shows the cost breakdown by building elements.
  2. Elements taking up the biggest cost are easily identified and can be adjusted as required.
  3. This estimate is good for cost planning i.e. the architect is advised to keep the client’s budget in mind when designing or optionally, the client can choose an affordable design among alternatives designed by the architect and priced by the quantity surveyor.
  4. The quantity surveyor is able to check the elemental costs throughout the design stage, which makes it a more reliable estimate than the superficial area method.
  5. Because all the main elements of a building are analyzed, and linked to BOQ items, this estimate is much more closer to the tender value than the superficial area method.
  6. Plan adjustments by the architect and re-pricing by the QS during the design stage eliminates a lot of pre-tender and post-tender BOQ amendments.

Disadvantages of Elemental Method of Estimating

  1. Plan adjustments and constant cost checking in the preliminary stage takes a lot of the Architect’s and Quantity Surveyor’s time.
  2. The Architect and QS involved in the preliminary stage need to be well versed with the cost implications of design specifications i.e. building materials, construction technology, plan shape etc.
  3. More work is needed in adjusting the Item Elemental Rate Build Up for BOQ linking.

 

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