Project Management, Estimating and Plan Reading
Project Management
Scheduling fundamentals
The bar chart communicates; the critical path method controls. A network shows activities, durations, and logic. The forward pass gives earliest dates, the backward pass gives latest dates, and the difference is float. The critical path is the longest-duration path through the network and carries zero total float - any delay there delays the project. Free float is how much an activity can slip without delaying its immediate successor; total float is how much it can slip without delaying project completion.
Control tools
Understand how submittals, RFIs, change orders, and schedule updates interlock. A submittal is a compliance and approval document, not a construction instruction; an RFI clarifies the documents; a change order modifies price, time, or both. Track progress by cost or earned value, and remember productivity is output divided by input.
Delays and money
Classify delays: excusable (owner-caused or neither party) versus non-excusable (contractor-caused); compensable versus non-compensable. Concurrent delays generally buy time but not money. Liquidated damages are a pre-agreed rate, not a penalty, and the owner must show the delay hit the critical path. A revised schedule is not automatically a time extension.
Traps and rule of thumb
Crashing or accelerating a non-critical activity buys nothing. Adding crews can cut duration less than expected. Confusing total float with free float is the most common error.
Worked example: path A–B–D = 5 + 8 + 6 = 19 days; path A–C–D = 5 + 4 + 6 = 15 days. Critical path is A–B–D; activity C has 4 days of total float.
Estimating and Plan Reading
Reading the set
A plan set is coordinated: site/plot plan, floor plans, elevations, sections, details, and schedules. Each view is drawn at a stated scale, and details are enlarged. Cross-check dimensions between views. When documents conflict, follow the contract's order of precedence - generally written dimensions over scaled measurements, and large-scale details over small-scale plans.
Takeoff mechanics
Measure in the units you will buy in and convert early: 1 cubic yard = 27 cubic feet; 1 acre = 43,560 sf; 1 roofing square = 100 sf; board feet = (thickness in inches × width in inches × length in feet) ÷ 12. Apply waste factors by material - larger for cut-up masonry and flooring, smaller for sheet goods. Keep quantity takeoff separate from pricing: quantities first, then labor, material, equipment, and subcontractor costs, then indirects, overhead, profit, and contingency.
Reading traps
Using the wrong scale (1/8" = 1'-0" versus 1/4" = 1'-0"), treating nominal lumber as actual (a 2×4 is 1½" × 3½"), misreading feet-and-inches notation, omitting items shown only in schedules (doors, windows, fixtures), and double-counting corners in wall or slab quantities.
Rule of thumb
For concrete, convert thickness to feet before multiplying. A 30' × 40' slab at 4 inches: 1,200 sf × 0.333 ft = 400 cf; 400 ÷ 27 = 14.8 cy; add 10% waste = 16.3 cy, so order 17 cy. Always confirm thickness and waste allowance against the drawings and specification.