BPC Commercial Builder (Unlimited) cheat sheet

Work breakdown structure (WBS) decomposes the project into deliverable-oriented packages; estimate line items should map one-to-one to WBS codes so quantities, labor, and cost roll up without double counting.

Quantity takeoff: compute net quantities from dimensions, then add waste/contingency factors by material (typical allowances: 5-10% for masonry and concrete, 10-15% for lumber and finishes, 3-5% for steel).

Unit-price bid = direct cost (material + labor + equipment) + indirect cost (supervision, temporary facilities, bonds, insurance) + overhead + profit + escalation.

Labor cost = quantity × labor hours per unit × loaded hourly wage; loaded wage = base wage × (1 + burden rate), where burden covers payroll taxes, insurance, and fringe.

Critical path method: total float = LS − ES = LF − EF; a path with zero total float is critical, and delaying it delays project completion.

Bid-day decision rule: bid when expected margin exceeds the cost of preparing the bid weighted by win probability; a low-margin bid is justified only by strategic value such as backlog fill or market entry.

Escalation formula: escalated cost = base cost × (1 + annual rate)^(months/12); apply escalation from the estimate basis date to the midpoint of construction.

Design-bid-build: owner holds separate contracts with designer and contractor. Design-build: one entity holds both. CM at risk: contractor joins during design and guarantees a maximum price (GMP).

Contract price types: lump sum (cost risk on contractor), unit price (risk shared by quantity variance), cost-plus with GMP (owner pays actual cost up to cap, savings shared per formula).

Retainage is a percentage withheld from each progress payment (commonly 5-10%) until substantial completion; it protects the owner against liens and defective work.

Standard AIA A201-type allocation: contractor bears risk of construction means and methods; owner bears risk of design defects and site conditions it concealed, subject to differing-site-condition notice.

Builder's risk insurance covers the structure under construction, materials in transit and storage, and soft costs from covered loss; it does not cover employee injury (workers' compensation) or contractor liability to third parties (general liability).

Risk transfer tools: performance and payment bonds, indemnity clauses, additional-insured endorsements, and subguard/contractor-controlled insurance programs (CCIP).

Risk register scores each risk as probability × impact; mitigation options are avoid, reduce, transfer, or accept, and residual risk is tracked after mitigation.

Soil classification by grain size: gravel > 4.75 mm, sand 0.075-4.75 mm, silt 0.002-0.075 mm, clay < 0.002 mm; plasticity and Atterberg limits distinguish silt from clay.

Swell and shrinkage: bank volume × (1 + swell) = loose volume; compacted volume = bank volume / (1 − shrinkage). Truck loads are priced on loose volume, payment on bank or compacted volume.

Excavation volume = plan area × depth; add side-slope volume for sloped cuts, and apply a 1:1 or flatter slope for safety in Type B/C soil unless shoring is used.

OSHA 1926 Subpart P: excavations 5 ft or deeper require a protective system (sloping, benching, shoring, or shielding) unless a competent person determines stable rock; ladders within 25 ft of travel for trenches 4 ft or deeper.

Spoil and surcharge must be kept at least 2 ft from the excavation edge; daily competent-person inspections are required before each shift and after rain.

Foundation types: spread footings for adequate bearing strata, mat/raft for low bearing capacity or high loads, deep foundations (piles, drilled shafts, caissons) when suitable soil is too deep for economical excavation.

Bearing capacity check: allowable bearing pressure ≥ service load / footing area; footing size is governed by the larger of bearing, overturning/sliding, or settlement criteria.

Concrete mix design: absolute volume method sums cement, water, air, fine aggregate, and coarse aggregate volumes to 1 cubic yard or 1 cubic meter; water-cement ratio controls strength and durability.

Concrete volume = length × width × depth; convert to cubic yards by dividing cubic feet by 27. Order 5-10% extra for slabs and footings, less for formed walls.

ACI 318 cover and curing rules: minimum cover depends on exposure and bar size; moist curing typically 7 days for normal cement, 3 days for Type III high-early cement.

Masonry: modular brick nominal 4 × 2⅔ × 8 in with ⅜-in mortar joints; count bricks per square foot of wall face (about 6.75 for modular) and add 5% breakage.

Masonry wall ties, reinforcement, and grouting: vertical reinforcement in grouted cells, horizontal joint reinforcement at intervals, and ties spaced per code to connect veneer to backup.

Structural steel takeoff: weight = length × weight per foot from the shape table; add connection material (plates, bolts, welds) as 3-8% of member weight and include primer/paint and fireproofing separately.

Bolted connections: snug-tight, pretensioned, and slip-critical are distinct; A325/A490 bolts are tensioned per turn-of-nut, calibrated wrench, or direct-tension-indicator methods.

Lumber nominal vs actual dimensions: 2 × 4 is 1½ × 3½ in, 2 × 6 is 1½ × 5½ in, 2 × 10 is 1½ × 9¼ in; board feet = (thickness in × width in × length ft) / 12 using nominal dimensions.

Lumber grading: visual grades (Select Structural, No. 1, No. 2, Stud) and machine-graded (MSR) set allowable bending stress Fb, shear Fv, and modulus E used in span tables.

Deflection limits per code: L/360 for live load on floors, L/240 for total load, L/180 or L/240 for ceilings depending on finish; span tables already assume these limits and standard loads.

Cold-formed steel framing: member designation like 600S162-54 means 6-in web, S-shape, 1⅝-in flange, 54-mil thickness; 33 mil ≈ 20 ga, 43 mil ≈ 18 ga, 54 mil ≈ 16 ga, 68 mil ≈ 14 ga.

CFS framing needs bridging, blocking, and clip angles for lateral support; screw spacing and size are specified by the engineer and are not interchangeable with wood fasteners.

Sheathing: panel span rating (e.g., 24/16) means maximum o.c. support spacing for roof (first number) and floor (second number); use exterior glue and proper nailing schedule for shear walls.

Framing takeoff: studs = wall length / spacing + 1 per wall plus corners and openings; plates = 3 lines per wall (top double, bottom single); add 10% waste for cuts and culls.

Thermal resistance: R-value of a layer = thickness / k (or 1/C); total assembly U-value = 1 / sum of R values including surface films; U is expressed in Btu/(h·ft²·°F).

Water vapor control: vapor retarders go on the warm side of the insulation in cold climates; in mixed climates use a Class II or variable-permeance retarder to allow drying.

Air barrier continuity is separate from vapor control; leakage at penetrations and transitions is a leading cause of condensation and energy loss.

Roofing slope rules: low-slope (≤ 3:12) uses membrane or built-up systems with laps and flashing; steep-slope (> 3:12) uses shingles, tile, or metal, with underlayment required.

Flashing details: base flashing at walls, counterflashing, step flashing at roof-wall intersections, and crickets/saddles behind chimneys wider than 30 in to divert water.

Drainage plane concept: wall assembly needs a drainage gap, weep holes at the base of brick veneer, and through-wall flashing at shelf angles and lintels.

Insulation types: batt (R-3.1 to 4.3 per inch), closed-cell spray foam (R-6 to 7 per inch, also an air/vapor retarder), open-cell foam (R-3.5 to 4 per inch, vapor permeable), rigid board (R-4 to 6.5 per inch).

Sensible and latent load: total cooling load = sensible + latent; equipment sizing uses Manual J-type block load with orientation, glazing, and internal gains, not rule-of-thumb square footage.

Duct sizing: equal friction method selects duct size for a target pressure drop per 100 ft (typically 0.08-0.10 in w.g.); velocity limits control noise (about 1,200 fpm in mains, 600 fpm in branches).

Electrical: Ohm's law V = I × R; power in watts = V × I × power factor for AC; panel load = connected load × demand factor, and service size must exceed calculated demand per code.

Voltage drop = (2 × K × I × L) / circular mils for single-phase; keep branch circuits under 3% and feeder plus branch under 5% total.

Conductor ampacity is derated for ambient temperature and conduit fill (more than 3 current-carrying conductors in a raceway); overcurrent protection matches the derated ampacity.

Plumbing: fixture units convert to probable peak flow; drain slope is ¼ in per foot for 2-in and smaller, ⅛ in per foot for 3-in and larger; venting protects trap seals.

Water supply sizing uses fixture units and equivalent length of pipe; pressure loss from friction plus elevation (0.433 psi per foot of rise) must leave minimum residual pressure at the fixture.

Drywall: ½-in for standard walls, ⅝-in Type X for fire-rated assemblies, ⅝-in or ½-in sag-resistant for ceilings at 24-in o.c.; finish levels 1-5 define joint treatment extent.

Fire-rated wall assemblies require listed systems with specified board type, layers, stud size and spacing, and fastener schedule; substitutions void the rating.

Paint coverage: about 350-400 sq ft per gallon per coat on smooth drywall; add 10-15% for porous or textured surfaces; primer plus two finish coats typical for new work.

Flooring: tile layout uses centerline or full-tile-at-entry rules; allow 10% waste for field tile and 15% for diagonal or patterned layouts; thin-set coverage requires 80-95% contact depending on use.

Door hardware: clear opening width for egress is typically 32 in minimum with a 36-in door; hardware height 34-48 in, operable with one hand without tight grasping.

Window performance: U-factor measures heat loss, SHGC measures solar gain, and VT is visible transmittance; in cooling-dominated climates specify low SHGC, in heating-dominated low U-factor.

Glazing safety: tempered glass required in hazardous locations such as doors, sidelights, glass near floors, and large panes, per code thresholds.

OSHA fall protection: 1926.501 requires protection at 6 ft in construction (general industry 4 ft); guardrails, safety nets, or personal fall arrest with anchorage rated 5,000 lb per worker.

Personal fall arrest: full-body harness, anchorage, and lanyard/deceleration device; maximum free-fall distance 6 ft and no contact with lower level; rescue plan required.

Scaffolding: 1926.451 requires a 10-ft maximum height between rest platforms, fully planked platforms, guardrails, and competent-person erection; do not load beyond rated capacity.

Hazard communication: Safety Data Sheets (SDS) must be accessible, containers labeled, and employees trained on chemical hazards under 1910.1200.

Permits and inspections: building permit, inspections at foundation, framing, rough-in, and final; a certificate of occupancy is issued only after final approvals.

Egress: two exits required above certain occupant loads and travel distances; exit width is based on occupant load × unit width factor, and exit signs and emergency lighting are required.

Hot work requires a written permit, fire watch during and 30 minutes after work, and removal of combustibles within 35 ft.