A wall footing is 0.60 m wide, 0.30 m thick and 25 m long. What volume of concrete is required?

4.50 m³. Volume = 0.60 × 0.30 × 25 = 4.50 m³. The value 7.50 m³ uses 0.60 × 0.50 × 25, and 0.45 m³ drops a factor of 10 in the length.

The direct cost of a pay item is ₱50,000. Indirect costs are 15% of direct cost and VAT is 12% of the subtotal. What is the total price?

₱64,400. The subtotal is 50,000 × 1.15 = ₱57,500, and adding 12% VAT gives 57,500 × 1.12 = ₱64,400. Adding the two percentages to direct cost only (50,000 × 1.27) gives ₱63,500, which understates the VAT. ₱57,500 omits VAT and ₱56,000 omits indirect costs.

How is formwork normally measured for payment?

By the square meter of form surface in contact with the concrete. Formwork is measured by contact area, the square meters of form face that touch the concrete, because labor and material vary with that area. Concrete is measured in cubic meters and reinforcement in kilograms.

Quantity Surveying, Unit Cost Analysis, and | Free Guide 2026

6.6 Quantity Surveying, Unit Cost Analysis, and Project Cost Estimates

The AMSTHC TOS area "Quantity Surveying" has five competencies:

Understand methods used to prepare building, bridge and construction cost estimates.
Review specifications, plans and details.
Analyze and derive unit costs for labor, material and equipment.
Apply methods of estimating for detailed quantity surveys.
Create a summary of total project costs.

Types of Estimates

Estimate	When used	Basis	Typical accuracy
Conceptual or order-of-magnitude	Feasibility	Cost per m² of floor area, per lane-km, per bed or per classroom	Rough
Preliminary	Schematic design	Major elements and assemblies	Moderate
Detailed (definitive)	Bidding and contract award	Complete takeoff of every pay item from final plans and specifications	Best

Bridge estimates are often built per element: foundations by piles, substructure by concrete and reinforcement, superstructure by girders and deck, plus approaches and slope protection.

Reading Plans and Specifications

Plans give dimensions and quantities. Specifications give quality, materials, workmanship and the method of measurement and basis of payment for each pay item.
Check scale, units and revision status. Reconcile plan and detail conflicts using the contract's order of precedence (Section 1.3).
Note items that are easy to miss: excavation and backfill, formwork, lap splices and hooks, embedded items, waterproofing, curing, scaffolding and temporary works.

Quantity Takeoff Methods

Work item	Unit	Takeoff rule
Excavation	m³	Net trench or pit volume, plus working space and slope where required
Concrete	m³	Net volume of each member; do not double-count beam-slab intersections
Formwork	m²	Contact area of concrete with the forms
Reinforcing steel	kg	Bar length × number × mass per meter, plus laps and hooks
CHB masonry	m² or pieces	Net wall area × 12.5 blocks/m²
Plastering, painting	m²	Net area of each face finished

Worked takeoff: isolated footing and pedestal. The footing is $2.0 \times 2.0 \times 0.40\text{ m}$ , and the pedestal is $0.40 \times 0.40 \times 1.20\text{ m}$ . Reinforcement is 10-16 mm bars each way in the footing, each $1.85\text{ m}$ long.

Concrete: footing $2.0(2.0)(0.40) = 1.600\text{ m}^3$ ; pedestal $0.40(0.40)(1.20) = 0.192\text{ m}^3$ ; total $1.792\text{ m}^3$ .
Formwork: footing sides $4(2.0)(0.40) = 3.20\text{ m}^2$ ; pedestal sides $4(0.40)(1.20) = 1.92\text{ m}^2$ ; total $5.12\text{ m}^2$ .
Footing bars: $2 \times 10 = 20$ bars × $1.85\text{ m}$ = $37.0\text{ m}$ , which at $1.58\text{ kg/m}$ is $58.5\text{ kg}$ .

Unit Cost Analysis

The detailed unit price analysis (DUPA) builds the cost of one unit of a pay item:

Component	How computed
Materials	Quantity of each material per unit × unit price, including waste allowance
Labor	Crew composition × daily rates ÷ crew output per day
Equipment	Equipment hours per unit × hourly rental or operating rate
Direct cost	Sum of the three
Indirect costs	Overhead, contingencies, miscellaneous expenses and contractor's profit, as percentages of direct cost
Value-added tax	Applied to direct plus indirect cost
Unit price	(Direct + indirect + VAT) per unit

Government agencies prescribe indirect-cost percentages and DUPA formats for their projects. Use the percentages given in the problem or in the current agency guideline.

Example: one cubic meter of concrete. Assume 9 bags of cement at ₱280, $0.50\text{ m}^3$ sand at ₱1,400 and $1.00\text{ m}^3$ gravel at ₱1,600.

Materials: ₱4,820, from $9(280) + 0.5(1{,}400) + 1.0(1{,}600) = 2{,}520 + 700 + 1{,}600$ .
Labor: a crew costing ₱8,000 per day places $8\text{ m}^3$ per day, so ₱1,000 per m³.
Mixer: ₱300 per m³.
Direct cost: ₱6,120.
With 15% indirect costs: ₱7,038, from $6{,}120 \times 1.15$ .
With 12% VAT: ₱7,883 per m³, from $7{,}038 \times 1.12$ .

Summary of Total Project Costs

A bill of quantities lists every pay item with quantity, unit, unit price and amount. The summary groups items by division and adds the following:

Line	Example (₱)
Earthworks	1,250,000
Concrete and reinforcement	6,800,000
Masonry and finishes	3,100,000
Steel and roofing	2,400,000
Plumbing, electrical and mechanical	2,950,000
Total direct cost	16,500,000
Indirect costs (overhead, contingency, miscellaneous, profit), say 15%	2,475,000
Subtotal	18,975,000
VAT 12%	2,277,000
Total project cost	21,252,000

Cross-check with a cost per square meter. For a $1{,}200\text{ m}^2$ building, ₱21.25 million is about ₱17,700/m². Compare that with similar recent projects to catch takeoff errors.

Tip

In board problems, read carefully whether VAT and indirect costs are already included in a given unit price, and whether waste allowances are to be added.

PRC Civil Engineering Licensure Examination

6.6 Quantity Surveying, Unit Cost Analysis, and Project Cost Estimates

Key Takeaways

6.6 Quantity Surveying, Unit Cost Analysis, and Project Cost Estimates

Types of Estimates

Reading Plans and Specifications

Quantity Takeoff Methods

Unit Cost Analysis

Summary of Total Project Costs