4.3 - Cost Estimating Methods

Question 1

What are the Principle Estimating Methods?

Answer 1

• Unit-Use Method
• Area/Volume Method
• Systems Method
• Unit-Price Method

Question 2

Describe the Unit-Use Method

Answer 2

• Also called Order of Magnitude or Ballpark estimate
• Based on historical data to the cost of a specific element
• +- 20% accuracy

Advantages:
- Quick reference at early design stages
Disadvantages:
- Projects are not identical, must consider how data is used

Question 3

Describe the Area/Volume Method

Answer 3

• Used when SD drawings indicates area and masses
• +- 15% accuracy

Advantages:
- Floor areas are easily applicable across all buildings
- Simple to calculate the costs of elements and apply historical data to areas and volumes
Disadvantages:
- Does not account for unique designs or conditions

Question 4

Describe the Systems Method

Answer 4

• Based on the sizes of spaces and elements used for the building (Area/Volume + Unit-Use Methods
• Up to 100% accuracy Advantages

Advantages:
- Contains lots of detailed information
Disadvantages:
- Not widely used
- Floor area may not represent costs for multi - storey

Question 5

Describe the Unit-Price Method

Answer 5

• Prepared using detailed information from working drawings, specs, and site visits
• Also called elemental costs
• +- 5% accuracy

Advantages:
- Applicable to new or existing buildings
- Process can proceed without construction drawings or specs fully complete
- Useful in DD to analyze tradeoffs without impacting budget
Disadvantages:
- Can be difficult to check information