CELE Construction Management & Methods — Construction Estimates and Quantity SurveyingConcept Map

Concept

Quantity Take-Off (QTO)

Sub Concepts

• Concrete Volume Calculation
• Reinforcing Steel Measurement
• Formwork Area Computation
• Earthwork Volumes
• Unit Mass Determination

Relationship To Central

Foundation process that measures materials directly from drawings before pricing

Concept

Concrete Estimation

Sub Concepts

• Volume Computation (L × W × H)
• Mix Design Classes (A, B, C)
• Cement Bags per m³
• Sand and Gravel Quantities
• Water-Cement Ratio
• Additives and Admixtures

Relationship To Central

Major quantity category requiring volume and material proportioning calculations

Concept

Reinforcing Steel Estimation

Sub Concepts

• Bar Diameter Classification
• Unit Mass Formula (0.006165d²)
• Total Bar Length Measurement
• Bar Bending Schedule
• Lap Splices and Anchorages
• Wire Ties and Accessories

Relationship To Central

Critical quantity takeoff using unit mass formula and bar scheduling

Concept

Formwork Estimation

Sub Concepts

• Contact Area Calculation
• Reuse and Recovery Rates
• Stripping Time Considerations
• Support Systems and Bracing
• Form Release Agents

Relationship To Central

Measurement of contact surfaces and structural support requirements

Concept

Unit Cost Development

Sub Concepts

• Material Costs
• Labor Costs and Productivity
• Equipment Costs and Rental
• Waste and Contingency Factors
• Market Price Fluctuations
• Supplier Quotations

Relationship To Central

Process of assigning costs to each measured quantity item

Concept

Direct Cost Computation

Sub Concepts

• Materials Subtotal
• Labor Subtotal
• Equipment Subtotal
• Waste Allowances
• Cost Breakdown by Trade

Relationship To Central

Sum of all material, labor, and equipment costs for the project

Concept

Bid Price Development

Sub Concepts

• Overhead Costs (OCM)
• Profit Margin
• Contingency Reserve
• Markup Percentage (15-25%)
• Value Added Tax (VAT)
• Bonds and Insurance

Relationship To Central

Final selling price calculated by adding markups to direct costs

Concept

Estimating Standards and References

Sub Concepts

• NSCP 2015 (Mix Proportions)
• ACI 318 (Reinforcement Requirements)
• AISC 360 (Steel Specifications)
• RA 544 (Philippine Construction Code)
• Industry Standard Productivity Rates
• Regional Material Pricing Data

Relationship To Central

Technical codes and formulas governing quantity and cost calculations

To

Concrete Estimation

From

Quantity Take-Off Process

Strength

strong

Relationship

QTO is the methodology; concrete estimation is one of its primary applications

To

Reinforcing Steel Estimation

From

Quantity Take-Off Process

Strength

strong

Relationship

QTO framework used to measure and document all steel bar quantities

To

Formwork Estimation

From

Quantity Take-Off Process

Strength

strong

Relationship

QTO quantifies formwork contact areas from drawing geometry

To

Unit Cost Development

From

Concrete Estimation

Strength

strong

Relationship

Calculated concrete volumes feed into unit pricing per cubic meter

To

Unit Cost Development

From

Reinforcing Steel Estimation

Strength

strong

Relationship

Steel masses determined by QTO are multiplied by unit cost per kilogram

To

Direct Cost Computation

From

Unit Cost Development

Strength

strong

Relationship

Unit costs multiplied by quantities yield line costs summed into direct cost

To

Bid Price Development

From

Direct Cost Computation

Strength

strong

Relationship

Direct cost is the foundation; markups applied to create bid price

To

Technical Standards and References

From

Bid Price Development

Strength

moderate

Relationship

NSCP 2015, ACI 318, AISC 360 standards ensure accurate quantity and cost calculations

To

Technical Standards and References

From

Concrete Estimation

Strength

strong

Relationship

NSCP 2015 defines mix classes (A, B, C) and cement proportions per m³

To

Technical Standards and References

From

Reinforcing Steel Estimation

Strength

strong

Relationship

ACI 318 and NSCP 2015 specify reinforcement requirements and unit mass calculations

To

Unit Cost Development

From

Formwork Estimation

Strength

moderate

Relationship

Formwork contact areas are priced per square meter

To

Direct Cost Computation

From

Earthwork

Strength

moderate

Relationship

Earthwork volumes calculated in QTO; costs added to total direct cost

To

Direct Cost Computation

From

Material Costs

Strength

strong

Relationship

Component of direct cost; includes concrete, steel, and other material expenses

To

Direct Cost Computation

From

Labor Costs

Strength

strong

Relationship

Component of direct cost; based on productivity rates and wage schedules

To

Direct Cost Computation

From

Equipment Costs

Strength

strong

Relationship

Component of direct cost; includes rental and operating expenses

To

Bid Price Development

From

Overhead and Contingency

Strength

strong

Relationship

OCM markup applied to direct cost (10% typical)

To

Bid Price Development

From

Profit Margin

Strength

strong

Relationship

Profit percentage applied to direct cost to yield contractor compensation

To

Unit Cost Development

From

Waste and Contingency Factors

Strength

moderate

Relationship

Waste allowances (5-10% for concrete, 2-5% for steel) increase quantities

To

Unit Mass Determination

From

Bar Diameter Classification

Strength

strong

Relationship

Diameter d in mm is input to unit mass formula 0.006165d²

To

Cement Bags per m³

From

Mix Design Classes

Strength

strong

Relationship

Class A (9 bags), Class B (7.5 bags), Class C (6 bags) - direct correspondence