Transcript Chapter 16: Budget Estimating

Chapter 16
Budget Estimating
Objectives
• Upon completion of this chapter, you will
be able to:
– Describe preliminary estimating options for
preparing budgets
– Identify the strengths and weaknesses of
each preliminary estimating option
– Differentiate single-rate methods from multirate methods of preliminary estimating
Objectives (cont’d.)
– Use the following techniques to prepare
preliminary estimates:
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Cost per unit
Cost per unit area
Cost per unit volume
Cost per typical bay
Assembly estimating
Develop unit prices for assembly estimates
Introduction
• Ways contractors obtain work
– Changed over the years
• Alternative project delivery methods
– Primary goal:
• Achieving project completion more quickly
Methods of Estimating
• Preliminary estimating methods
– Used to compile a budget
• When there is too little information for a
detailed estimate
• Categories:
– Single-rate methods
– Multi-rate methods
Single-Rate Methods
• Price per unit
– Common unit is selected
• Number of them is calculated for each project
– Strengths and weaknesses:
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Quick; requires little data; easily communicated
Useful for rough check or comparisons
Can be an indication of design efficiency
Some data is published on unit costs
Low accuracy and no rate breakdowns
Price Per Unit Area
• Unit of analysis: square foot or meter of
gross floor area
– Area of all floors outside containing walls
– Strengths and weaknesses:
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Quick; requires little data; widely used
Useful for rough check or comparisons
Large amount of data is published
Accurate only for small buildings
No breakdown of single rate
Price Per Unit Volume
• Obtained by dividing total construction
cost by building volume
– Strengths and weaknesses:
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Quick; requires little data; easy to communicate
Useful for rough check or comparisons
Some unit area costs data is published
Not widely used
Accurate with only similar buildings
No rate breakdown
Multi-Rate Methods
• Price per typical bay
– Divides floor area into bays
• Uses column gridlines
– Strengths and weaknesses:
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More accurate but requires more calculations
Prices can be put together from publications
Used for comparison and cost control
Cannot be used on all buildings
Not widely used
Assembly Estimates
• Objective: measuring and pricing
assemblies that comprise a group
– Strengths and weaknesses:
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More accurate but requires more calculations
Can be used with any building design
Large amount of data is published
Used for comparison and cost control
Poor accuracy resulting from assumptions
Can involve a lot of calculating
Figure 16.2
Office/Showroom
Preliminary Notes
Figure 16.3
Assembly Estimate
Figure 16.4
Concrete Grade
Beam Assembly
Elemental Estimates
• Most sophisticated preliminary
estimating technique
– Greatest ability to manage project costs
• Conception to construction
– Refer to Chapter 17
Summary
• Single-rate methods:
– Cost per unit
– Cost per unit area
– Cost per unit volume
• Multi-rate methods:
– Cost per typical bay
– Assembly estimates
– Elemental estimates