Introduction
Cost planning is the process by which a quantity surveyor establishes and controls a construction project’s budget as the design develops, well before full detailed drawings — and therefore a full Bill of Quantities — are available. At the center of this process sits elemental cost analysis, a structured method of breaking a building’s total cost into standardized functional elements (substructure, superstructure, finishes, services, and so on). This article explains how elemental cost planning works, why it’s structured the way it is, and how to build and interpret a cost plan using a worked example.
Why Cost Planning Is Needed Before a Full Bill of Quantities Exists
Early in a project, only a concept design exists — floor areas, a general form, an approximate specification level — not the detailed drawings needed to measure exact quantities of brick, concrete, or steel. Yet clients need reliable budget figures at this stage to decide whether to proceed, secure financing, and set a realistic design brief. Elemental cost planning solves this problem by working at a higher level of abstraction: rather than measuring exact quantities, it estimates cost per functional element, calibrated against historical data from comparable completed projects.
The Standard Building Elements
Most elemental cost planning frameworks (such as the RICS New Rules of Measurement, NRM1) break a building down into a standard set of elements, allowing cost data to be consistently compared across different projects. A simplified version of this structure includes:
| Element Group | Included Components |
|---|---|
| Substructure | Foundations, ground floor slab, damp-proofing |
| Superstructure | Frame, upper floors, roof, external walls, windows, internal walls, doors |
| Finishes | Wall, floor, and ceiling finishes |
| Fittings and Furnishings | Fitted furniture, sanitary fittings |
| Services | Mechanical, electrical, plumbing, lifts, fire protection |
| External Works | Site works, drainage, external services |
| Preliminaries | Site management, temporary works, insurance |
The Elemental Cost Planning Process
Step 1: Establish the Order of Cost Estimate
At the earliest stage, before any elemental breakdown is possible, a QS often produces a single-figure order of cost estimate, typically based on a cost-per-square-metre benchmark from comparable buildings.
Worked example: For a proposed 4,000 m² mid-range office building, using a benchmark of $2,400/m² (drawn from recent comparable project data), the order of cost estimate would be:
4,000 m² × $2,400/m² = $9,600,000
Step 2: Develop the Elemental Cost Plan
As design develops, the single total figure is broken down across the standard elements, typically expressed both as a percentage of total cost and a cost per square metre, allowing the design team to see where the budget is concentrated.
Worked example — Elemental cost plan for the $9,600,000 office building:
| Element | % of Total Cost | Cost ($) | Cost per m² |
|---|---|---|---|
| Substructure | 8% | 768,000 | 192 |
| Superstructure | 40% | 3,840,000 | 960 |
| Finishes | 15% | 1,440,000 | 360 |
| Fittings | 3% | 288,000 | 72 |
| Services | 22% | 2,112,000 | 528 |
| External Works | 7% | 672,000 | 168 |
| Preliminaries | 5% | 480,000 | 120 |
| Total | 100% | 9,600,000 | 2,400 |
Step 3: Benchmark Against Historical Data
Each elemental figure is checked against a database of historical cost analyses from comparable completed buildings, adjusted for factors such as location, market conditions, and specification level. If the “Services” figure above (22%) looks unusually high compared to a benchmark range of typically 15–20% for this building type, the QS would investigate why — perhaps the project includes an unusually complex mechanical system — and flag this to the design team early, while changes are still relatively cheap to make.
Step 4: Update the Cost Plan as Design Develops
As the design becomes more detailed, the cost plan is progressively refined — moving from broad percentage-based elemental estimates toward more detailed quantity-based pricing as drawings allow, eventually converging with the full Bill of Quantities once tender documentation is prepared.
Why Working at the Elemental Level (Not Just Total Cost) Matters
- Early warning of imbalance: If one element consumes a disproportionate share of budget, this is visible immediately, allowing early design adjustment rather than a late, costly redesign.
- Supports value engineering: Because costs are broken down by function, it becomes much easier to identify which elements offer the best opportunities for cost reduction without compromising overall building performance (see our companion article on value engineering for more detail on this process).
- Enables meaningful comparison across projects: Because the elemental structure is standardized, a QS can compare a project’s cost profile against dozens of historical comparables, element by element, rather than relying on a single crude total.
Adjusting Benchmark Data: Key Factors
Historical cost data is never applied directly without adjustment. QSs typically apply corrections for:
- Location factors: Construction costs vary significantly by region and even by city, often expressed as a location index relative to a national average.
- Time/inflation adjustment: Historical data must be updated to current price levels using a relevant cost index (such as a national tender price index).
- Specification differences: A benchmark project with a higher or lower specification level (e.g., premium finishes vs. standard finishes) must be adjusted accordingly.
- Building size and shape efficiency: Smaller or more complex-shaped buildings typically have a higher cost per square metre due to a less efficient ratio of external wall/perimeter to floor area.
Common Mistakes Students Make in Elemental Cost Planning
- Treating benchmark data as exact rather than indicative: Historical cost data provides a starting range, not a precise figure — it must always be critically adjusted for the specific project’s circumstances.
- Ignoring preliminaries and contingency: Students often focus heavily on the “visible” building elements and underestimate preliminaries (site overheads) and risk/contingency allowances, which can represent a significant share of total project cost.
- Failing to update the cost plan iteratively: Cost planning is not a one-time exercise; it should be revisited and refined at each design stage as more information becomes available.
Students working on elemental cost planning and construction estimating assignments can apply these principles when developing cost plans, interpreting benchmark data, and justifying their calculations. For additional support with quantity surveying coursework, see our Quantity Surveying Assignment Help guide.
Frequently Asked Questions
Q: What is the difference between an order of cost estimate and an elemental cost plan? A: An order of cost estimate is typically a single, high-level figure based on overall cost-per-square-metre benchmarking, produced at the earliest project stage, while an elemental cost plan breaks that total down across standardized building elements once slightly more design information is available.
Q: Where does elemental cost data typically come from? A: It’s usually drawn from a database of cost analyses of previously completed, comparable projects, often maintained internally by a consultancy or sourced from published industry cost data services.
Q: How often should a cost plan be updated during design development? A: Best practice is to review and refine the cost plan at each significant design stage (concept, developed design, technical design), ensuring the budget remains aligned with the evolving design rather than being fixed once early in the process.
Q: Why is the superstructure typically the largest cost element? A: The superstructure includes major structural and enclosure components (frame, upper floors, roof, external walls, windows), which together typically represent the largest physical volume of construction work in most building types.
Q: How does elemental cost analysis relate to value engineering? A: Because elemental cost analysis breaks down cost by function, it directly supports value engineering by making it clear which elements represent the largest cost opportunities for potential redesign or specification changes without compromising the building’s core function.
