OK General Contractor cheat sheet

Critical path method: the longest continuous path through the network; total project duration equals the critical path length, and any delay on it delays completion unless float is recovered.

Float (slack) = late start minus early start, or late finish minus early finish; float is shared on a path, so consuming it affects every activity on that path.

Retainage in Oklahoma private construction is commonly 5-10% of each progress payment; on public contracts retainage is limited by statute to 5% of the contract price.

Earned value: CPI = EV/AC (cost efficiency), SPI = EV/PV (schedule efficiency); CPI below 1.0 means over budget, SPI below 1.0 means behind schedule.

Estimate at completion (EAC) = BAC/CPI when current cost performance is expected to continue; VAC = BAC minus EAC.

Change order pricing should be agreed before work proceeds; absent agreement, use force-account (time and materials) with documented labor rates, equipment, and markup.

A pay-when-paid clause shifts payment risk downstream but does not eliminate the prime contractor's ultimate obligation to the owner's satisfaction of conditions precedent.

Submittal review turnaround is governed by the contract's specified review period; approval does not relieve the contractor of responsibility for dimensional or coordination errors.

Scale conversion: measured length on paper x denominator of the scale (e.g., 1/4 inch = 1 foot means 1 inch on paper equals 4 feet) gives actual length.

Plan symbols: solid line = visible edge, dashed = hidden, centerline (long-short dash) = axis of symmetry or structural grid; grid lines are lettered one way and numbered the other.

Section cut marks show the drawing sheet and detail number; elevation marks show a datum triangle with the finished floor value relative to a stated benchmark.

Quantity takeoff for concrete: volume = length x width x depth in consistent units; divide cubic feet by 27 for cubic yards, then add waste (typically 5-10%).

Rebar weight: No. 4 bar = 0.668 lb/ft, No. 5 = 1.043 lb/ft, No. 6 = 1.502 lb/ft; weight per foot = (bar number squared)/2.67 approximately.

Masonry count: modular brick (nominally 3-5/8 x 2-1/4 x 7-5/8 in) with 3/8 in joints yields about 6.75 brick per square foot of wall face.

Board feet = (thickness in inches x width in inches x length in feet)/12; lumber is priced per thousand board feet (MBF).

Contingency is added to the base estimate for undefined scope; escalation adjusts for cost change between estimate date and construction date.

Swell is the increase in volume when soil is excavated and loosened; shrinkage is the decrease when compacted fill is placed. Bank volume x (1 + swell) = loose volume.

Compaction is specified as a percentage of maximum dry density from a standard (Proctor) or modified Proctor test; typical structural fill requires 95% of standard Proctor.

Optimum moisture content produces maximum dry density; adding water or drying soil moves density toward that peak.

Cut and fill balance: net volume = cut volume minus fill volume divided by (1 - shrinkage) for compacted fill; haul distance determines whether to waste, borrow, or move on site.

Slope stability: angle of repose for granular soil approximates the internal friction angle; temporary excavations 5 ft or deeper require a protective system under OSHA 1926 Subpart P.

Trench spoil must be kept at least 2 ft back from the excavation edge to reduce surcharge loading on the trench walls.

Stormwater: silt fence, sediment basins, and stabilized construction entrances are typical BMPs; a Stormwater Pollution Prevention Plan (SWPPP) is required for covered construction sites.

Erosion vs. sediment control: erosion control prevents soil detachment (mulch, matting), sediment control traps moved soil (silt fence, traps).

Water-cement ratio controls strength and durability: lower w/c means higher strength and lower permeability; typical structural mixes run 0.40-0.50.

Concrete must be placed within its specified workability window; generally discharge within 90 minutes of batching unless a retarder is approved.

Curing maintains moisture and temperature; moist curing for 7 days is typical for Type I cement, and cold-weather protection is required when ambient falls near or below 40 F.

Formwork removal: vertical forms may be removed when concrete is strong enough to resist damage; soffit forms under beams and slabs require strength verification or specified curing periods.

Reinforcement cover protects steel from corrosion and provides fire resistance; cover requirements vary by exposure and member, commonly 1.5 to 3 inches for cast-in-place against earth.

Masonry mortar joints: head and bed joints are typically 3/8 inch; mortar type M is highest strength, Type N is general-purpose above grade, Type S is moderate-high strength.

Masonry wall ties, flashing, and weep holes form the drainage plane; flashing must lap and terminate with weep holes at the base of the cavity.

Grout in reinforced masonry must fill cells completely; grout lift height and consolidation by puddling or vibration are specified by code and must be inspected.

Structural steel connections: bolted connections use A325/A490 (or F3125) high-strength bolts; slip-critical joints require specified minimum tension and turn-of-nut or tension-calibrated tightening.

Welding symbols: arrow points to the joint, the reference line carries the weld symbol above (other side) or below (arrow side); a tail holds process or reference notes.

Steel erection tolerances and plumbness are checked before final bolting; shimming and leveling nuts correct base plate elevation.

Wood grading: visually graded lumber is stamped with grade, species, and moisture content; design values differ by grade and species, and Fb (bending) is adjusted for size and duration.

Nominal vs. dressed lumber: a 2x4 is actually 1-1/2 x 3-1/2 inches; nominal dimensions are used for naming, actual for design checks.

Wood connectors: joist hangers, hold-downs, and straps must be installed with the manufacturer's specified fasteners; substituting nails voids the listed capacity.

Moisture content matters: lumber installed at high moisture shrinks as it dries, causing gaps and nail pops; kiln-dried framing is typically 19% or less.

Fire-retardant treatment and preservative treatment are distinct; exposed structural wood in rated assemblies must match the listed assembly's treatment and species.

R-value is thermal resistance; U-factor is its reciprocal (U = 1/R). Assembly U-factors combine parallel paths by area-weighted average.

Vapor retarders belong on the warm side of the assembly in cold climates; in hot-humid climates, vapor drive can reverse and placement must follow climate-specific guidance.

Air barriers control infiltration, which can dominate heat loss; a continuous air barrier must be sealed and aligned with the insulation layer.

Water management: drain the cavity, flash the openings, and lap materials shingle-style so upper layers shed over lower ones.

Window performance: U-factor measures heat flow, SHGC measures solar heat gain; low SHGC reduces cooling loads in cooling-dominated climates like Oklahoma.

Flashing sequence at openings: sill pan first, then jambs, then head; head flashing laps over the sides and the weather-resistive barrier laps over the head flange.

Doors and windows require shimming at hinge and lock points and anchoring per manufacturer; rough opening dimensions are the framed opening, not the unit size.

Thermal bridging through steel studs and slab edges reduces effective R-value; continuous exterior insulation breaks the bridge.

Coordination drawings (composite or BIM clash detection) resolve conflicts between ductwork, piping, conduit, and structure before installation.

Slope requirements: sanitary drain lines typically slope 1/4 inch per foot for 2-inch and smaller, 1/8 inch per foot for 3-inch and larger, per plumbing code.

Duct sizing: velocity method and equal-friction method are common; friction loss is expressed in inches of water per 100 ft of duct.

Electrical: conductors are sized by ampacity and protected by overcurrent devices; voltage drop should be limited, commonly to 3% on branch circuits and 5% total.

Clearances: working space in front of electrical equipment (typically 36 inches, greater for higher voltages) must be kept clear and cannot be used for storage.

Penetrations through rated assemblies require listed firestop systems; fire dampers are required where ducts penetrate fire-rated walls or floors.

Rough-in inspections must occur before concealment; pressure testing of drain, waste, and vent systems and of water piping is required before closure.

Equipment access and service clearance: maintain manufacturer-required clearances for coil replacement, filter access, and electrical disconnects.

OSHA 1926 Subpart M: fall protection is required at 6 ft or more in construction; guardrails, safety nets, or personal fall arrest systems are acceptable.

Fall arrest systems must limit maximum arresting force to 1,800 lb and keep free fall to 6 ft or less; anchorages must support 5,000 lb per worker or be designed by a qualified person.

Excavations 5 ft or deeper require a protective system unless the excavation is entirely in stable rock; trenches 4 ft or deeper require a means of egress within 25 ft of lateral travel.

Scaffolding: guardrails required at 10 ft or more; the scaffold must be designed by a qualified person and erected by trained workers, with footing on stable base.

Hazard communication: Safety Data Sheets must be accessible, containers labeled, and employees trained on chemical hazards under 29 CFR 1910.1200.

Personal protective equipment: hard hats, eye protection, and hearing protection are required where hazards exist; PPE is the last line of defense in the hierarchy of controls.

Environmental: asbestos and lead require survey and abatement by certified workers before demolition; disposal of regulated waste follows EPA and state rules.

Recordkeeping: OSHA 300 log entries are required for work-related injuries and illnesses; fatalities must be reported within 8 hours, in-patient hospitalizations within 24 hours.

Oklahoma Construction Industries Board (CIB) licenses trade contractors and administers the state's construction codes; local jurisdictions may adopt and enforce their own codes.

Oklahoma adopted the Oklahoma Uniform Building Code Commission (OUBCC) codes, which are based on the International Codes; verify the edition and local amendments before bidding.

Mechanics' and materialmen's liens in Oklahoma: a pre-lien notice is required for certain claimants, and a lien statement must be filed with the county clerk within the statutory period (generally 90 days after last furnishing labor or materials for most claimants).

An owner may demand a lien statement; failure to respond within the statutory time can bar the lien. Suit to foreclose a lien must be filed within the statutory period after filing.

On public works, mechanics' liens do not attach to public property; the bond claim process (Little Miller Act equivalent under Oklahoma statutes) provides the remedy.

Contractor licensing: a state contractor license is required for many trades; unlicensed contracting can bar recovery of compensation and expose the contractor to penalties.

Lien waivers: a conditional waiver becomes effective upon payment; an unconditional waiver is effective on signing, so never sign one before funds clear.

Prompt payment: Oklahoma statutes set payment timelines for public contracts; for private work, contract terms govern, but pay-when-paid clauses are construed strictly.

Roof pitch is rise over run; a 4:12 pitch means 4 inches of rise per 12 inches of horizontal run, giving a slope factor of about 1.054 for area calculations.

Area of a triangle = 1/2 x base x height; area of a trapezoid = average of parallel sides x height; break irregular takeoffs into simple shapes.

Concrete slab on grade: add for thickened edges and footings separately; vapor retarder and reinforcement are measured by area or weight.

Steel takeoff: weight = length x weight per foot from the AISC manual; add for connections, base plates, and miscellaneous items by percentage.

Drywall: board count = wall area divided by board area, plus 10% waste; joint compound and tape are estimated per 1,000 sq ft of board.

Painting: coverage rates are stated per gallon (typically 350-400 sq ft per coat); number of coats and surface porosity affect quantity.

Labor productivity is expressed in units per labor hour or hours per unit; crew size times hours gives labor cost when multiplied by the loaded rate.

Plan reading order: cover sheet and index, general notes, life safety plan, floor plans, elevations, sections, details, and schedules; cross-check dimensions between views.

Soil classification by USCS groups: GW, GP, GM, GC (gravels); SW, SP, SM, SC (sands); ML, CL, OL (silts and clays of low plasticity); MH, CH, OH (high plasticity).

Liquid limit and plasticity index describe fine-grained soil behavior; high PI indicates expansive clay, common in Oklahoma and requiring special foundation treatment.

Expansive soils: mitigate with over-excavation and replacement, moisture conditioning, or pier foundations extending below the active zone.

Bearing capacity is verified by geotechnical investigation; spread footings, drilled piers, and mat foundations are selected based on soil report recommendations.

Subgrade preparation includes proof-rolling, scarifying, moisture conditioning, and compaction in lifts typically 6-8 inches loose.

Dewatering: sumps and pumps for shallow groundwater; wellpoints for deeper drawdown; discharge must be managed to avoid erosion and comply with permits.

Utility locating: call 811 before digging; Oklahoma requires notification before excavation so public utilities can mark their lines.

Grade stakes and laser levels establish elevation control; benchmarks must be tied to a known datum and protected during construction.

Concrete mix design: cement, water, fine aggregate, coarse aggregate, and admixtures; air entrainment improves freeze-thaw resistance in exterior concrete.

Slump test (ASTM C143) measures workability; cylinders (ASTM C39) are tested at 7 and 28 days, with 28-day strength typically the design criterion.

Hot weather concreting: reduce slump loss by cooling ingredients, using retarders, and placing promptly; avoid adding water at the job site.

Cold weather concreting: maintain concrete temperature above 50 F during protection period; use accelerators and insulating blankets as needed.

Masonry reinforcement: horizontal joint reinforcement and bond beams with rebar provide crack control and lateral strength.

Mortar and grout are different materials; grout has higher water content and is placed in reinforced cells, while mortar bonds units.

Efflorescence is a cosmetic salt deposit from moisture migration; it indicates water entry and should be addressed at the source, not just cleaned.

Control joints in concrete and masonry are planned crack locations; spacing depends on panel aspect ratio and thickness, typically 2-3 times thickness in feet for slabs.

Steel beam designations: W-shapes are wide-flange, S-shapes are standard I-beams, and C-shapes are channels; the depth and weight per foot identify the section (e.g., W12x26).

Composite construction uses shear studs to transfer force between steel beam and concrete slab, increasing effective strength.

Light-gauge steel framing: studs are designated by web depth, flange width, and gauge; screws and welds are typical connections.

Wood trusses are engineered components; field modifications, notching, or cutting chords voids the design and requires an engineer's approval.

Notching and boring limits for joists: notches in the top or bottom edge are limited in depth and location; holes must be centered and sized per code.

Decay and termites: pressure-treated wood is required where wood contacts masonry or concrete, and in areas of high termite hazard.

Fireblocking and draftstopping limit concealed air movement in wood-frame assemblies; required at floor levels and in concealed chases.

Metal studs require careful layout for opening framing and backing; blocking must be installed for cabinets, grab bars, and heavy fixtures.

Insulation types: batt, blown-in, spray foam, rigid board; spray foam provides air sealing in addition to insulation.

Attic ventilation: intake at soffits and exhaust at ridge or gable; balanced ventilation extends roof life and reduces moisture problems.

Roof underlayment is a secondary moisture barrier; ice and water shield is required at eaves in cold climates and at valleys.

Roofing slope: low-slope roofs (less than 3:12) use membrane or built-up systems; steep-slope roofs use shingles, tile, or metal.

Window and door installation: use the manufacturer's flashing details; sealant alone is not a substitute for proper flashing.

Moisture in buildings: control bulk water first, then capillary, then air-transported moisture, then vapor diffusion; air leakage moves far more moisture than diffusion.

Thermal envelope continuity: insulate and air-seal at rim joists, penetrations, and transitions to prevent condensation and energy loss.

Door hardware and egress: egress doors must swing in the direction of travel where required by occupancy and must have panic hardware in assembly occupancies.

HVAC load calculation uses Manual J or equivalent; equipment sizing must match the calculated load, not rules of thumb.

Duct leakage testing is required in many codes; sealing ducts in conditioned space improves efficiency and comfort.

Refrigerant piping: line sizes and lengths are specified by the manufacturer; excessive length or vertical rise reduces capacity.

Plumbing vents protect trap seals; each fixture requires a vent unless it is a listed fixture with an approved air admittance valve.

Water heater seismic and thermal expansion: expansion tanks and temperature-pressure relief valves are required; discharge piping must terminate safely.

Electrical grounding and bonding: grounding electrode system, equipment grounding conductors, and bonding of metallic piping are required for safety.

Panel schedules and circuit directories must be accurate and updated; spare capacity should be planned for future loads.

Coordination of hangers and supports: duct, pipe, and conduit supports must not conflict with structure; seismic bracing may be required.

Hazard Communication Standard (HazCom) requires a written program, labeling, SDS access, and training for employees exposed to hazardous chemicals.

Lockout/tagout (1910.147) controls hazardous energy during servicing; only authorized employees may perform lockout.

Confined spaces: permit-required confined spaces require atmospheric testing, ventilation, attendant, and rescue plan before entry.

Cranes and rigging: qualified rigger and signal person requirements; load charts must be followed, and swing radius must be barricaded.

Electrical safety: GFCI protection is required for temporary receptacles on construction sites; extension cords must be inspected and rated for hard usage.

Housekeeping and walking-working surfaces: keep walkways clear, cover or guard floor openings, and maintain safe access.

Environmental permits: NPDES construction general permit for stormwater; air permits for demolition and dust-generating activities may apply.

Spill prevention and response: store fuels and chemicals with secondary containment; have spill kits and trained responders on site.

Oklahoma requires contractors to be licensed by the Construction Industries Board for many trades; license classifications determine the scope and value of work allowed.

Bonding: contractors may be required to post a surety bond as a condition of licensure; public works contracts require performance and payment bonds above statutory thresholds.

Lien deadlines in Oklahoma are strict; missing the filing or suit deadline generally extinguishes the lien right regardless of the merits of the claim.

A notice of lien should be served on the owner and, where required, on the prime contractor; proof of service is important evidence.

Contractors should obtain a preliminary notice or pre-lien notice where required to preserve lien rights; requirements differ for subcontractors and suppliers.

Oklahoma's consumer protection laws and the CIB complaint process allow homeowners to file complaints against licensed contractors for violations.

Contract terms: written contracts should state scope, price, payment schedule, change order procedure, and dispute resolution; oral contracts are enforceable but harder to prove.

Warranty and call-back obligations: express warranties in the contract govern; implied warranties of workmanlike quality may apply even without an express term.