Estimating & Cost Control

22% of this exam

Quantity takeoff, unit conversions, waste factors, labor burden and productivity, plus earned-value cost control. Calculation-heavy: the conversions (27 CF per CY) and formulas (CPI = EV ÷ AC) do the work, and unit discipline decides whether you get the right answer.

Core concepts

Takeoff is units, then arithmetic

A quantity takeoff measures and lists the materials, labor, and equipment from the plans — the foundation of the estimate. Convert everything to the unit being priced before computing: concrete volume in cubic feet ÷ 27 = cubic yards. Add waste with quantity × (1 + waste factor) — 2,000 SF of tile at 8% waste = 2,160 SF.

Labor cost = productivity + burden

Productivity rates convert quantity to duration: quantity ÷ crew output per day = crew-days (12,000 SF ÷ 800 SF/day = 15 crew-days). Labor burden adds payroll taxes, workers' comp and liability insurance, and fringes on top of the base wage — pricing labor at the bare wage understates true cost.

Know your cost buckets

Direct costs are incorporated into the work (footing rebar, concrete). General conditions are project-specific overhead — superintendent, field office, temporary utilities. Home office rent and accounting are general overhead, recovered through markup. Questions test which bucket a cost belongs in.

Estimate types and earned value

Early in design, use a conceptual (order-of-magnitude) estimate from historical cost per square foot; detailed unit-price estimates need substantially complete documents. For cost control, CPI = earned value ÷ actual cost — below 1.0 means over budget. CPI measures cost efficiency, not schedule.

Key facts to know cold

Cubic yard conversion27 cubic feet = 1 cubic yard — the most-used number in Walker's
Waste factorOrder quantity = net quantity × (1 + waste %)
Crew durationQuantity ÷ crew output per day = crew-days
CPIEarned value ÷ actual cost; < 1.0 = over budget
Labor burdenTaxes + workers' comp + insurance + fringes added to base wage
General conditionsJob-specific overhead (super, field office, temp power) — not home office

See it drawn out

Fig — Quantity → cost: the three conversions
  1. Volume
    L × W × D ÷ 27 = cubic yards (slab: 100 × 50 × 0.5 ÷ 27 ≈ 93 CY)
  2. Waste
    Net quantity × (1 + waste factor) (tile: 2,000 SF × 1.08 = 2,160 SF)
  3. Labor
    Quantity ÷ production rate = crew-days (12,000 SF ÷ 800 = 15)

Where it lives in your books

The real exam is open book. Knowing which book — and which tab — answers this domain is worth as much as memorizing it.

Lookup strategy

  • · Walker's conversion and waste-factor tables are organized by trade division — tab the concrete and masonry tables, the usual question sources.
  • · Earned value formulas (CPI, SPI) sit in the cost-control chapter of the PM text; verify the formula before plugging numbers, since inverted ratios are the standard distractor.

Reading isn't learning — retrieval is.

15 questions in this domain, each with an explanation and source.