📚 Contractor Terms Glossary
Comprehensive Terminology Guide for California Contractor License Exam
📋 General Contracting Terms
Addendum
A written document issued before bidding that clarifies, corrects, or adds to the original bid documents. Unlike change orders (which occur after contract award), addenda modify the project scope before contractors submit bids.
As-Built Drawings
Documentation showing how a project was actually constructed, including any deviations from the original plans. These record actual locations of utilities, structural elements, and systems for future reference and maintenance.
Bid
A formal offer submitted by a contractor to perform specified work at a stated price. Bids typically include detailed breakdowns of labor, materials, equipment, overhead, and profit costs. May be sealed (private until opening) or open.
Bid Bond
A financial guarantee submitted with a bid that ensures the contractor will enter into a contract if awarded the project. Typically 5-10% of bid amount. Protects the owner if winning bidder refuses to sign the contract.
Change Order
A written document that modifies the original contract by adding, deleting, or changing the scope of work, timeline, or contract price. Must be signed by both parties to be valid and enforceable.
Completion Date
The date when a project is substantially complete and ready for occupancy and use as intended, even if minor punch list items remain. Important for warranty start dates and final payment triggers.
Contract Documents
The complete set of documents that define the construction project, including: drawings, specifications, contract agreement, general conditions, addenda, change orders, and any other modifications. Collectively forms the legal binding agreement.
Cost-Plus Contract
A contract type where the owner pays the contractor for actual costs incurred (labor, materials, equipment) plus an agreed-upon fee or percentage for profit and overhead. Requires detailed documentation of all expenses.
Critical Path
The sequence of project activities that determines the minimum time needed to complete the project. Any delay in critical path activities directly delays project completion. Used in project scheduling and management.
Design-Build
A project delivery method where one entity (the design-builder) provides both design and construction services under a single contract. Contrasts with traditional design-bid-build where design and construction are separate contracts.
Liquidated Damages
Pre-determined monetary amounts specified in the contract that the contractor must pay for each day the project is delayed beyond the completion date. Not a penalty, but a reasonable estimate of owner's damages from delay.
Lien
A legal claim against property to secure payment for work performed or materials supplied. Mechanics liens protect contractors, subcontractors, and suppliers if payment is not received. Must follow strict notice and timing requirements to be valid.
Lien Release (Waiver)
A document signed by a contractor, subcontractor, or supplier that relinquishes their right to file a mechanics lien, usually in exchange for payment. Can be conditional (upon payment clearing) or unconditional (immediate).
Notice to Proceed
A written communication from the owner authorizing the contractor to begin work and establishing the official start date for the project schedule. Critical for calculating contract time and completion dates.
Payment Application
A formal request for payment submitted periodically (usually monthly) showing work completed, materials stored, retainage withheld, and amounts due. Often follows specific formats like AIA G702/G703.
Performance Bond
A surety bond guaranteeing that the contractor will complete the work according to contract terms. If contractor defaults, the surety must complete the work or pay the owner. Common on public projects and large private projects.
Prime Contractor (General Contractor)
The main contractor who has a direct contract with the property owner and overall responsibility for project completion. Typically hires and manages subcontractors for specialty trades.
Punch List
A document listing minor repairs, incomplete items, or deficiencies that need to be finished before final payment and project completion. Created during final inspection walkthrough with owner and/or architect.
Retainage (Retention)
A percentage of each progress payment (typically 5-10%) withheld by the owner until project completion. Provides security that contractor will complete all work including punch list items. Released upon final completion.
RFI (Request for Information)
A formal written request to clarify ambiguities, discrepancies, or missing information in construction documents. Should be submitted early to avoid delays and get timely responses from architect or engineer.
Schedule of Values
A detailed breakdown of the total contract price into component parts (sitework, foundation, framing, etc.) with values assigned to each. Used as the basis for monthly payment applications showing percentage complete.
Scope of Work
A detailed description of all work to be performed, materials to be provided, and services to be rendered under the contract. Defines project boundaries and what is included (and excluded) from the contract price.
Submittal
Shop drawings, product data, samples, or other information submitted by the contractor to the architect/engineer for review and approval before materials are ordered or work proceeds. Required for quality control.
Subcontractor
A specialized contractor hired by the general contractor to perform specific portions of work (electrical, plumbing, HVAC, etc.). Has contract with general contractor, not directly with owner.
Substantial Completion
The stage when work is sufficiently complete that the owner can occupy and use the project for its intended purpose, even though minor items remain on the punch list. Triggers warranty periods and final payment timeline.
Time and Materials (T&M)
A contract type where the contractor is paid for actual hours worked (at specified rates) plus materials costs (often with markup). Used when scope is uncertain. Requires detailed daily tracking and client approval.
Unit Price
A set price for a specific unit of work or material (per square foot, per linear foot, per cubic yard, etc.). Used when exact quantities are unknown at bidding. Final payment based on actual quantities installed.
Value Engineering
The process of reviewing design and materials to identify cost savings while maintaining or improving quality and function. May involve substituting materials, changing methods, or redesigning systems for efficiency.
Warranty
A contractor's guarantee to repair or replace defective work or materials for a specified period after completion. Typical periods: one year for workmanship, longer for specific systems or materials per manufacturer warranties.
📐 Blueprint & Drawing Terms
Architectural Drawings
Plans showing the design, appearance, and layout of a building including floor plans, elevations, and details. Focus on aesthetics, space planning, and building envelope rather than structural or systems engineering.
Blueprint
Traditional term for construction drawings (historically blue with white lines). Now generally refers to any construction drawing or plan, regardless of actual printing method or color. Contains all information needed to build the project.
Detail Drawing
A large-scale drawing showing specific construction methods, connections, or assemblies. Provides precise dimensions, materials, and installation instructions for complex or critical elements. Typically at larger scale than general plans (1/2" = 1'-0" or larger).
Elevation
A drawing showing a vertical view of a building's exterior or interior wall. Shows heights, vertical dimensions, materials, finishes, and appearance. Named by direction (North elevation, East elevation) or by room/area.
Floor Plan
A horizontal drawing showing the layout of a building level as if viewed from above with the roof removed. Shows room sizes, door/window locations, wall thicknesses, and spatial relationships. Primary drawing for understanding building layout.
Legend
A chart or list on drawings explaining the meaning of symbols, abbreviations, line types, and notations used in the plans. Essential reference for correctly interpreting all drawing information.
Mechanical Drawings
Plans showing HVAC, plumbing, and sometimes fire protection systems. Include equipment locations, duct/pipe routing, sizes, and specifications. Created by mechanical engineers and used by HVAC and plumbing contractors.
Plat
A map showing property boundaries, lot lines, easements, rights-of-way, and sometimes topography. Used for site planning, zoning compliance, and establishing legal property descriptions. Filed with county recorder.
Reflected Ceiling Plan
A drawing showing the ceiling as if reflected in a mirror on the floor. Shows ceiling heights, lighting fixtures, HVAC diffusers, sprinkler heads, and ceiling materials. Used for coordinating ceiling-mounted systems.
Scale
The ratio between measurements on a drawing and actual measurements in the real world. Common scales: 1/4" = 1'-0" (meaning 1/4 inch on paper equals 1 foot in reality), 1/8" = 1'-0", 1" = 10'-0". Allows large buildings to fit on manageable-sized drawings.
Section
A drawing showing a vertical slice through a building or component to reveal interior construction details, structural elements, and relationships between components. Like cutting the building with a giant saw and viewing the cut edge.
Shop Drawings
Detailed drawings prepared by contractors, fabricators, or suppliers showing exactly how specific components will be fabricated, assembled, or installed. More detailed than construction documents. Require architect/engineer review and approval before fabrication.
Site Plan
A drawing showing the building's location on the property, including property lines, setbacks, access drives, parking, utilities, landscaping, grading, and drainage. Shows relationship of building to site and surroundings.
Specifications (Specs)
Written documents describing materials, workmanship, standards, quality requirements, and installation methods for a construction project. Organized by CSI divisions. Complement drawings by providing information not shown graphically. Part of contract documents.
Structural Drawings
Plans showing the building's structural system including foundations, beams, columns, load-bearing walls, floor framing, and roof framing. Prepared by structural engineers. Include sizes, materials, reinforcement, and connections required for structural integrity.
Title Block
Information box on each drawing sheet containing project name, address, architect/engineer information, sheet number, date, revisions, and drawing scale. Provides identification and organization for the drawing set.
⚡ Electrical Terms
AFC (Arc-Fault Circuit Interrupter)
A circuit breaker that detects dangerous arcing conditions and quickly shuts off power to prevent electrical fires. Required in bedrooms and many other areas per National Electrical Code. More advanced than standard breakers.
Ampacity
The maximum current-carrying capacity of a conductor (wire) expressed in amperes. Depends on wire size, insulation type, ambient temperature, and installation conditions. Must not be exceeded to prevent overheating.
Amperage (Amps)
The measurement of electrical current flow, representing the rate at which electrons flow through a conductor. Higher amperage indicates more current. Related to voltage and resistance through Ohm's Law. Standard household circuits are typically 15 or 20 amps.
AWG (American Wire Gauge)
The standardized system for measuring wire diameter in North America. Counter-intuitively, larger numbers mean smaller wires. Common sizes: 14 AWG (15 amp circuits), 12 AWG (20 amp), 10 AWG (30 amp), 8 AWG (40-50 amp).
Branch Circuit
The portion of electrical wiring between the final overcurrent protection device (circuit breaker) and the electrical outlets or fixtures. Each circuit typically serves multiple outlets or lights in an area or room.
Circuit Breaker
A reusable safety device that automatically interrupts electrical flow when current exceeds safe levels, protecting wires from overheating and fire. Can be manually reset after tripping. Replaces older fuse technology in most modern installations.
Conductor
Any material that allows electricity to flow through it. In construction, typically refers to electrical wires made of copper or aluminum. Hot (current-carrying), neutral (return path), and ground (safety) are different types of conductors.
Conduit
Protective tubing that houses electrical wires, providing physical protection and ease of wire replacement. Types include: rigid metal (RMC), intermediate metal (IMC), electrical metallic tubing (EMT), and PVC. Required in exposed locations and commercial buildings.
Feeder
Conductors that supply power from the service equipment (main panel) to branch circuit panels or large equipment. Larger than branch circuit wires. Must be sized based on total load and voltage drop considerations.
GFCI (Ground Fault Circuit Interrupter)
A life-saving safety device that detects ground faults and quickly shuts off power (within milliseconds) to prevent electric shock. Required in wet locations: bathrooms, kitchens, garages, outdoors, basements, and within 6 feet of sinks. Available as outlets or circuit breakers.
Grounding
Connecting electrical systems and metal components to the earth to provide a safe path for fault currents and prevent electric shock. The grounding system includes ground rods, grounding electrode conductors, and equipment grounding conductors throughout the building.
Junction Box
An enclosure protecting electrical wire connections (splices). Required wherever wires are joined together. Must be accessible (not concealed by drywall) for future inspection and maintenance. Size depends on number and size of conductors.
Load
The total electrical demand on a circuit or system, measured in watts or amperes. Includes all connected devices, lights, and equipment. Must be calculated to properly size circuits, wires, and panels.
NEC (National Electrical Code)
The comprehensive set of electrical standards adopted in most US jurisdictions for safe electrical installation. Published by NFPA, updated every 3 years. California adopts NEC with some state amendments in California Electrical Code.
Ohm
The unit of measurement for electrical resistance. Higher resistance means less current flow. Named after Georg Ohm. Related to voltage and current through Ohm's Law: V = I × R.
Overcurrent Protection
Devices (circuit breakers or fuses) that protect electrical circuits from excessive current that could cause overheating and fires. Must be properly sized for the conductor ampacity they protect.
Panelboard (Load Center)
An electrical distribution point where branch circuits originate, containing circuit breakers or fuses. Fed by larger feeder conductors. Houses multiple circuit breakers in an organized enclosure. Also called breaker panel or fuse box.
Raceway
Any enclosed channel designed for holding wires or cables. Includes conduit, cable trays, wireways, and other systems. Provides physical protection and organization for electrical conductors.
Romex (NM Cable)
Brand name for non-metallic sheathed cable commonly used in residential wiring. Contains two or more insulated conductors plus ground, all wrapped in plastic sheath. Allowed in dry interior locations but not outdoors or in commercial buildings.
Service Panel (Main Panel)
The main electrical distribution point where power enters a building from the utility. Contains the main disconnect breaker and distributes power to branch circuits or subpanels. Rated by amperage (100A, 200A, 400A, etc.).
Service Entrance
The conductors and equipment connecting the utility power lines to the building's electrical system. Includes the meter, service disconnect, and all associated hardware. Point where utility responsibility ends and building owner's begins.
Short Circuit
An abnormal connection between two conductors (hot to neutral or hot to ground) creating very high current flow. Circuit breakers or fuses protect against short circuits by quickly interrupting power.
Three-Phase Power
An electrical system with three alternating currents offset by 120 degrees, providing more efficient power delivery. Common in commercial/industrial settings. Allows smaller wire sizes for same power delivery compared to single-phase. Typical voltages: 208V, 240V, 480V.
Transformer
An electrical device that changes voltage levels up or down. Steps down high utility voltage (typically 7,200V to 34,500V) to usable building voltage (120/240V residential). Uses electromagnetic induction with no moving parts.
Voltage
The electrical "pressure" that pushes current through a conductor, measured in volts. Standard household voltage is 120 volts for outlets and lights, 240 volts for large appliances (dryers, ranges, air conditioners). Higher voltage allows more power with same current.
Volt-Ampere (VA)
A measure of apparent power in an electrical circuit. For purely resistive loads (heaters, incandescent lights), watts and VA are equal. For inductive loads (motors), VA is higher than watts due to power factor.
Wattage
The measurement of actual electrical power consumed or produced, measured in watts. Calculated by multiplying voltage times amperage (W = V × A) for resistive loads. One kilowatt (kW) = 1,000 watts. Used for sizing circuits and calculating electrical costs.
💧 Plumbing Terms
ABS (Acrylonitrile Butadiene Styrene)
Black plastic pipe commonly used for drain, waste, and vent (DWV) systems in residential plumbing. Joined with solvent cement. Approved for use above ground. Lighter and less expensive than cast iron, easier to work with than PVC in cold weather.
Air Gap
A physical separation between the water outlet and the flood level rim of a fixture, preventing contaminated water from siphoning back into the potable water supply. Critical for backflow prevention. Common on dishwashers and commercial sinks.
Backflow Preventer
A device preventing contaminated water from flowing backward into the potable water supply. Required on irrigation systems, commercial buildings, and anywhere non-potable water connects to supply lines. Various types based on hazard level.
Building Drain
The lowest horizontal drain pipe in a building that receives discharge from all drainage pipes and conveys it to the building sewer outside the foundation. Typically 4" minimum diameter for residential, larger for commercial buildings.
Building Sewer
The pipe carrying wastewater from the building drain to the public sewer main or private septic system. Located outside the building foundation. Owner's responsibility typically ends at connection to public main. Must have proper slope (minimum 1/4" per foot).
Cleanout
An accessible opening in a drainage system that allows clearing blockages or inspecting the line. Required at specific locations per code: changes in direction, base of stacks, and regular intervals in horizontal runs. Capped with removable plug.
Copper Pipe (Types K, L, M)
Metal tubing used for water supply lines. Type K: Thickest wall, used underground. Type L: Medium wall, common for interior residential. Type M: Thinnest wall, adequate for most residential applications. Joined by soldering, compression, or push-fit fittings.
CPVC (Chlorinated Polyvinyl Chloride)
Rigid plastic pipe approved for hot and cold water supply lines. Can handle higher temperatures than PVC. Joined with solvent cement. Less expensive than copper, easier to install, but not as durable. Common in residential construction.
DWV (Drain, Waste, and Vent)
The complete plumbing system that removes wastewater and sewer gases from a building. Drain pipes carry waste, waste pipes carry toilet discharge, vent pipes allow air circulation and gas escape. Entirely separate from water supply system.
Fixture Unit (DFU - Drainage Fixture Unit)
A standardized measure of the discharge load a plumbing fixture places on the drainage system. Used to size drain pipes and vents. Examples: toilet = 3 DFU, lavatory = 1 DFU, shower = 2 DFU, kitchen sink = 2 DFU.
Hose Bibb (Sillcock)
An outdoor water faucet typically mounted on an exterior wall. Should be frost-proof in cold climates (valve seat located inside heated space). Requires backflow prevention if hose can reach below grade level.
P-Trap
A curved section of drain pipe shaped like the letter "P" that holds water to create a seal, preventing sewer gases from entering the building. Required on all fixtures connected to drainage systems. Water seal typically 2-4 inches deep. Must not lose water seal through siphonage or evaporation.
PEX (Cross-linked Polyethylene)
Flexible plastic tubing increasingly popular for hot and cold water supply lines. Easier to install than rigid pipe, fewer fittings needed, resistant to freezing damage and corrosion. Joined with crimped, expansion, or push-fit fittings. Cannot be used outdoors (UV degradation).
Potable Water
Water that is safe for human consumption, meeting health and safety standards for drinking. Must be kept completely separate from non-potable water sources (irrigation, fire suppression, gray water). Protected by backflow prevention devices and air gaps.
PRV (Pressure Reducing Valve)
A valve that automatically reduces incoming water pressure to a safer, more manageable level. Required when supply pressure exceeds 80 PSI. Protects fixtures and appliances from damage, reduces water waste, quiets water hammer. Adjustable, typically set to 50-60 PSI.
PVC (Polyvinyl Chloride)
White or cream-colored rigid plastic pipe commonly used for cold water supply, drainage, and venting. Cannot be used for hot water (use CPVC instead). Joined with solvent cement. Lightweight, corrosion-resistant, economical. Schedule 40 for most residential, Schedule 80 for higher pressure.
Rough-In
The installation of all plumbing pipes, drains, and vents behind walls and under floors before walls are closed. Critical stage requiring inspection before concealing. Fixtures are not installed until finish stage. Rough-in dimensions must match fixture specifications.
Sanitary Sewer
A pipe system that carries wastewater (sewage) from buildings to a treatment plant. Completely separate from storm sewers that carry rainwater. Combined sewers (handling both) are being phased out. Flows by gravity where possible.
Septic System
An on-site wastewater treatment system used where public sewers aren't available. Consists of septic tank (settling and partial treatment) and drain field (final treatment in soil). Requires regular pumping and maintenance. Size based on building occupancy and soil conditions.
Shut-Off Valve
A valve that controls water flow to a fixture, appliance, or section of plumbing. Required at each fixture for maintenance and repairs. Main shut-off valve controls water to entire building. Should be operated periodically to prevent seizing.
Sump Pump
A submersible or pedestal pump installed in a basement sump pit to remove collected groundwater or surface water, preventing flooding. Automatically activated by float switch when water reaches certain level. Should have battery backup for power outages.
Supply Line
Pipes carrying potable water from the main supply to fixtures and appliances. Under pressure (40-80 PSI). Hot and cold supply lines run parallel. Must be sized adequately for flow rates and pressure. Smaller than drain pipes (typically 1/2" to 3/4" for residential fixtures).
Trap Arm
The horizontal section of drain pipe between a fixture's trap and the vent. Has maximum length limits per code to prevent trap siphonage. Slope 1/4" per foot toward drain. Must be properly sized based on fixture type.
UPC (Uniform Plumbing Code)
The primary plumbing code used in California and western United States. Published by IAPMO, updated every 3 years. California adopts UPC with state amendments in California Plumbing Code. Covers all aspects of plumbing systems, materials, and installation.
Vent Pipe (Vent Stack)
A vertical pipe providing air circulation in the drainage system, allowing sewer gases to escape through the roof and preventing trap siphonage. Every fixture drain must be vented. Extends through roof with weather protection. Minimum 1-1/2" diameter, typically same size as drain it serves.
Water Hammer
A banging noise in pipes caused by sudden water flow stoppage creating pressure waves. Prevented by air chambers or water hammer arrestors near quick-closing valves (washing machines, dishwashers). Can damage pipes and connections over time if not addressed.
Water Meter
A device measuring water consumption, typically installed at the property line. Utility company's property and responsibility. Records volume in gallons or cubic feet. Often includes shut-off valve. Foundation of utility billing. May be inside or outside depending on climate and local standards.
WPG (Water Pressure Gauge)
A device measuring water pressure in pounds per square inch (PSI). Ideal residential pressure: 50-60 PSI. Below 40 PSI: insufficient flow. Above 80 PSI: requires pressure reducing valve. Useful for diagnosing pressure problems.
🌡️ HVAC Terms
AFUE (Annual Fuel Utilization Efficiency)
A percentage rating of how efficiently a furnace converts fuel to heat over a heating season. Higher ratings mean less wasted fuel. Minimum 80% for new furnaces, high-efficiency models 90-98%. A 95% AFUE means 95% of fuel becomes heat, 5% is lost.
Air Handler
The indoor component of a heat pump or air conditioning system containing the blower fan, evaporator coil, and air filter. Circulates conditioned air through ductwork. May also include electric heating elements for backup or supplemental heat.
BTU (British Thermal Unit)
A measurement of heating or cooling capacity. One BTU is the energy needed to raise one pound of water by one degree Fahrenheit. HVAC equipment capacity typically measured in thousands of BTUs per hour. 12,000 BTU/hour = 1 ton of cooling.
CFM (Cubic Feet per Minute)
A measurement of airflow volume, indicating how much air an HVAC system moves in one minute. Critical for proper heating/cooling distribution. Residential systems typically 350-450 CFM per ton of cooling. Measured with anemometer or flow hood.
Compressor
The heart of an air conditioning or heat pump system. Pumps and compresses refrigerant, creating pressure differences that allow heat transfer. Most expensive component to replace. Located in outdoor condensing unit. Failure often means full system replacement.
Condenser
The outdoor component of an air conditioning or heat pump system. Contains compressor, condenser coil, and fan. Releases heat absorbed from inside air to outdoors during cooling. In heating mode (heat pump), absorbs heat from outdoor air.
Damper
A movable plate in ductwork that regulates airflow to different areas or zones. Can be manual (set and forget) or automatic (motorized, controlled by thermostats). Balancing dampers adjust system airflow. Zone dampers control comfort in different areas independently.
Ductwork
The network of pipes or channels distributing heated or cooled air throughout a building. Supply ducts deliver conditioned air to rooms, return ducts bring air back to equipment. Must be properly sized, sealed, and insulated for efficiency. Common materials: sheet metal, flex duct, duct board.
EER (Energy Efficiency Ratio)
A rating of cooling efficiency at a specific outdoor temperature (95°F). Calculated by dividing cooling output (BTU/hr) by power input (watts). Higher numbers indicate more efficient equipment. Useful for comparing systems, but SEER is more comprehensive for overall efficiency.
Evaporator Coil
The indoor coil where refrigerant evaporates, absorbing heat from indoor air. Located in air handler or furnace. Works with outdoor condenser to provide cooling. Must be cleaned periodically for efficiency. Frozen coil indicates airflow or refrigerant problems.
Heat Exchanger
A component in furnaces that transfers heat from combustion gases to circulating air without mixing them. Combustion gases stay isolated and vent outdoors. Cracked heat exchangers are dangerous (carbon monoxide risk) and usually require furnace replacement. Critical safety component inspected during maintenance.
Heat Pump
A reversible air conditioning system that provides both cooling and heating. Works by transferring heat rather than generating it. Very efficient in moderate climates. May require supplemental heating in extreme cold. Uses same equipment for both heating and cooling by reversing refrigerant flow.
HSPF (Heating Seasonal Performance Factor)
A rating of heat pump heating efficiency. Higher numbers indicate more efficient heating. Minimum 8.2 for new equipment, high-efficiency models 10+. Similar to SEER but for heating mode. Important for heat pump selection in heating climates.
MERV (Minimum Efficiency Reporting Value)
A rating system for air filter effectiveness at capturing particles. Scale 1-16, higher is better filtration. MERV 8: Standard residential. MERV 11-13: Better filtration for allergies. MERV 16: HEPA filter quality. Higher MERV requires more fan power or more frequent changes.
Plenum
A large air distribution box connecting the HVAC unit to the ductwork. Supply plenum distributes conditioned air to supply ducts. Return plenum collects air from return ducts. Typically insulated sheet metal. Critical junction point in duct system requiring proper sealing.
Refrigerant
The chemical substance that absorbs and releases heat in air conditioning and refrigeration systems. Circulates between indoor and outdoor units, changing between liquid and gas states. Common types: R-410A (current standard), R-22 (being phased out). Requires EPA-certified technicians to handle.
SEER (Seasonal Energy Efficiency Ratio)
A rating measuring air conditioner or heat pump cooling efficiency over an entire season. Calculated by dividing total cooling output by total electrical energy input. Minimum 14-15 for new equipment (varies by region), high-efficiency models 18-25+. Higher SEER = lower operating costs.
Split System
The most common HVAC configuration with components split between indoor (evaporator coil, air handler/furnace) and outdoor (condenser unit). Connected by refrigerant lines. Contrasts with packaged systems where all components are in one outdoor unit.
Static Pressure
The resistance to airflow in ductwork, measured in inches of water column. Too high indicates restricted airflow (dirty filters, closed dampers, undersized ducts). Too low indicates leaky ducts. Proper static pressure essential for system efficiency and longevity.
Subcooling
The amount refrigerant is cooled below its condensation temperature. Measured at the outdoor unit. Proper subcooling (10-15°F typically) indicates correct refrigerant charge. Too high or low indicates overcharge or undercharge. Critical diagnostic measurement for system performance.
Superheat
The amount refrigerant is heated above its boiling point. Measured at the indoor coil. Proper superheat (5-15°F typically) indicates correct refrigerant charge and airflow. Used with subcooling to diagnose charging and airflow problems. Essential for system efficiency and longevity.
Thermostat
A device that senses temperature and controls the HVAC system to maintain desired comfort levels. Types: Manual, programmable, smart/WiFi-enabled. Location critical: interior wall, away from drafts/sunlight/heat sources. Programmable models save energy by reducing heating/cooling when occupants away or sleeping.
Ton (of Cooling)
A unit of cooling capacity equal to 12,000 BTU/hour. Based on the heat needed to melt one ton of ice in 24 hours. Residential systems typically 1.5-5 tons. Proper sizing critical: oversized systems short-cycle and don't dehumidify, undersized can't maintain comfort.
Zoning
Dividing a building into separate areas (zones) with independent temperature control. Uses multiple thermostats and motorized dampers. Provides customized comfort and energy savings by heating/cooling only occupied areas. Requires proper design to prevent pressure problems.
⚖️ Legal & Regulatory Terms
Building Code
Legal requirements establishing minimum standards for construction to ensure public safety, health, and welfare. Covers structural integrity, fire safety, accessibility, energy efficiency, and life safety. California uses International Building Code with state amendments (California Building Code). Local jurisdictions may add requirements.
Cal/OSHA
California's Division of Occupational Safety and Health, enforcing workplace safety regulations. More stringent than federal OSHA in many areas. Covers fall protection, scaffolding, trenching, hazard communication, and all workplace safety matters. Violations result in citations and fines. Contractors must comply with all regulations.
Certificate of Occupancy (CO)
An official document issued by the building department certifying that a structure complies with all codes and is safe for occupancy and use. Required before buildings can be occupied or utilities connected. Final step after all inspections passed. For new construction, additions, and changes of use.
CSLB (Contractors State License Board)
The California state agency that licenses and regulates contractors to ensure competence and protect consumers. Issues contractor licenses, investigates complaints, enforces licensing laws, and disciplines violators. Part of Department of Consumer Affairs. Contractors must comply with all CSLB regulations.
Indemnification
A contractual obligation where one party agrees to compensate another for losses or damages. Common in construction contracts where contractor agrees to indemnify (protect) owner from claims arising from contractor's work. Review indemnification clauses carefully as they transfer risk and liability.
Lien Waiver
A document where a contractor, subcontractor, or supplier waives their right to file a mechanics lien, usually in exchange for payment. Conditional waivers: effective upon payment clearing. Unconditional waivers: effective immediately. Critical for protecting property owners and facilitating payments.
OSHA (Occupational Safety and Health Administration)
Federal agency setting and enforcing workplace safety regulations. In California, Cal/OSHA administers both federal and state safety standards. All construction employers must comply with OSHA standards for worker protection. Serious violations result in substantial fines and potential criminal charges.
Permit
Official authorization from the building department to perform specified construction work. Required for most structural, electrical, plumbing, and mechanical work. Ensures work meets codes and is properly inspected. Work without required permits is illegal and can result in fines, stop-work orders, and liability issues.
Right-of-Way
A legal right to pass through property owned by another party. Utilities often have right-of-way easements for access to power lines, water mains, sewer lines. Construction may require permits when work affects right-of-way areas. Cannot block or obstruct established rights-of-way.
Setback
The minimum required distance between a structure and property lines, streets, or other features. Established by zoning ordinances. Front, rear, and side setbacks vary by zone. Violations can require structure removal or relocation. Verify setbacks before beginning construction.
Stop Work Order
An official directive from a building inspector or code enforcement officer requiring immediate cessation of work due to code violations, safety concerns, or unpermitted work. All work must stop until issues are resolved and order is lifted. Continuing work results in additional penalties and potential criminal charges.
Variance
Official permission to deviate from zoning or building code requirements when strict compliance creates undue hardship and deviation won't compromise safety. Requires application, hearing, and approval by zoning board or building official. Limited to specific situations where literal enforcement is impractical.
Workers' Compensation Insurance
Insurance providing medical benefits and wage replacement to employees injured on the job, regardless of fault. Required in California for most contractors with employees. Protects both workers and employers from lawsuit exposure. Rates vary by classification based on risk. Penalties for non-compliance are severe.
Zoning
Local government regulations controlling land use, building types, density, and development standards in different areas. Designations include residential, commercial, industrial, agricultural, mixed-use. Must comply with zoning before obtaining building permits. Changes require variance or rezoning.