The Definitive Plumbing Estimating Glossary

Plumbing estimating requires knowledge of piping systems, fixtures, codes and installation methods. From understanding drainage calculations to specifying the right fixtures and materials, this comprehensive glossary covers the essential terminology for accurate plumbing estimates.

This guide includes both plumbing-specific technical terms and general estimating terminology used throughout the bidding and project execution process.

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

A

ABS (Acrylonitrile Butadiene Styrene) – A black plastic pipe commonly used for drain, waste and vent (DWV) systems. Less expensive than cast iron but not approved in all jurisdictions. Estimated by linear foot with separate fittings.

Addendum – A document issued during the bidding period that modifies or clarifies the original plans and specifications. All estimators must acknowledge and incorporate addenda into their bids, affecting scope and pricing.

Allowance – A specified dollar amount included in an estimate for materials or fixtures not yet selected. Common for finish plumbing fixtures, allowing the owner to make selections later while keeping the bid complete.

Angle Stop – A shut-off valve installed between water supply lines and fixture supply tubes, typically at toilets and sinks. Counted individually and specified by size, connection type and finish.

Assembly – A grouping of related materials and labor into a single estimating unit. Examples include complete toilet rough-in assemblies or water heater installations with all components, improving estimating speed and accuracy.

B

Backflow Preventer – A device preventing the reverse flow of water from plumbing systems back into the potable water supply. Required at various locations by code, with pricing varying significantly by type (atmospheric vacuum breaker, pressure vacuum breaker, reduced pressure zone, double check valve).

Ball Valve – A shut-off valve using a rotating ball with a bore through it. More expensive than gate valves initially but offering superior performance and longevity.

Bid – A formal proposal submitted by a contractor offering to perform work for a specified price. Plumbing estimates become bids when submitted to general contractors or owners.

Bid Day – The deadline for submitting bids on a project. Estimators often receive last-minute quotes from suppliers and subcontractors, requiring quick analysis and bid compilation.

Bill of Materials (BOM) – A detailed list of all materials, quantities, and specifications needed for a plumbing project.

Boiler – A closed vessel in which water is heated to produce hot water or steam. Major cost item in estimates, priced by BTU input, type (cast iron, fire tube, condensing) and features.

Branch – A lateral or subsidiary drainage line. Estimated by measuring runs from fixtures to the main stack or building drain.

Building Drain – The lowest horizontal piping of a drainage system collecting discharge from all drainage pipes and conveying it to the building sewer. Critical component sized based on fixture unit calculations.

Building Sewer – The pipe conveying discharge from the building drain to the public sewer or private disposal system. Often includes excavation, bedding and backfill in the estimate pricing.

C

Cast Iron Pipe – Heavy, durable pipe traditionally used for DWV systems. More expensive than plastic but offering sound-dampening properties valued in multi-family construction.

Change Order – A written modification to the contract, changing scope, price or schedule. Estimators must price change orders using similar methods as original estimates, often with premium pricing for disruption.

Cleanout – An access point in drainage systems for clearing blockages. Required by code at specific locations and counted individually in takeoffs.

Contingency – A percentage or dollar amount added to an estimate to cover unforeseen conditions or minor scope changes. Typically, 3-10% depending on project complexity and risk.

Copper Pipe – Metal pipe used for water supply systems. Available in Types K, L and M with different wall thicknesses and prices. Estimated by linear foot with separate fittings.

Cost Code – A numeric classification system used to track costs by category, phase, or trade.

CPVC (Chlorinated Polyvinyl Chloride) – A plastic pipe used for hot and cold-water distribution. Less expensive than copper with easier installation, reducing labor costs.

Crew Size – The number of workers assigned to a task, affecting productivity rates and labor costs. Larger crews may reduce duration but increase coordination challenges.

Cut Sheet – A manufacturer's product specification page showing dimensions, features and technical data. Essential for verifying that estimated materials meet specification requirements.

D

Design-Build – A project delivery method where the contractor provides both design and construction services. Estimating occurs earlier with less complete information, requiring more assumptions and contingency.

Dielectric Union – A fitting with an insulating material that prevents galvanic corrosion when joining dissimilar metals. Required when connecting copper to steel or galvanized pipe.

Digital Takeoff – Electronic quantification of plumbing materials and fixtures using software.

Direct Costs – Expenses directly attributable to a specific project, including material, labor and equipment. Distinguished from indirect costs (overhead) in estimate breakdowns.

Drainage Fixture Unit (DFU) – A measure of probable discharge into the drainage system by various plumbing fixtures. Used to size drainage pipes per code tables, fundamental to proper system design and estimation.

Drain-Waste-Vent (DWV) – The system of pipes removing wastewater and sewage from a building while providing air circulation. Complete system estimation requires coordination of drains, wastes, vents and cleanouts.

E

Ejector Pump – A pump lifting sewage or wastewater from below the sewer level. Major cost item including pump, basin, piping, electrical work and venting requirements.

Escalation – The projected increase in material or labor costs over time. Important for projects with long schedules or delayed starts, typically expressed as an annual percentage.

F

Faucet – A valve controlling water flow at a fixture. Pricing varies dramatically based on quality, finish and features. Must specify mounting type (deck mount/wall mount), hole count and special features.

Fixture – A receptacle or device connected to the plumbing system and receiving or discharging water. Each fixture type has standard rough-in requirements and pricing.

Fixture Count – The total number of plumbing fixtures in a project. Foundation of estimating, with fixture units used for pipe sizing calculations.

Fixture Unit – A design factor representing the probable discharge of different fixtures, used to size drainage and water supply systems per code. Critical for proper pipe sizing in estimates.

Floor Plan – An architectural drawing showing the layout of a building level. Primary source for fixture locations and rough counts in preliminary estimates.

G

GPM (Gallons Per Minute) – The unit measuring water flow rate. Used to size water supply systems and select pumps, fixtures and water heaters.

Grease Interceptor – A device separating and retaining fats, oils and grease from wastewater. Required in commercial kitchen installations as a major line item, including installation, piping and venting.

H

Historical Data – Records of actual costs from previous projects used to improve estimating accuracy. Valuable for validating production rates and unit costs.

Hose Bibb – An outdoor faucet with a male hose thread connection. Requires freeze-proof type in cold climates, counted individually with specifications for mounting and draining type.

Hot Water Circulation System – A system maintains hot water temperature throughout the distribution piping. Includes circulating pump, controls, return piping and increased energy costs for operation.

I

Indirect Costs – Overhead expenses not directly tied to a specific project, including office rent, utilities, insurance and administrative salaries. Applied to estimates as a percentage markup.

L

Labor Burden – Additional costs beyond base wages, including payroll taxes, workers' compensation insurance, benefits and paid time off. Typically adds 35-60% to base labor rates.

Labor Unit – The amount of work time required to install a specific item, typically expressed in man-hours per unit. Foundation of labor cost estimating.

Lavatory – A bathroom sink with a basin and drain. Estimated based on mounting type (wall-hung, countertop, pedestal), size and quality grade.

Lead Time – The duration between ordering materials and delivery. Long lead items like custom fixtures or specialized equipment must be identified early to avoid schedule delays.

Line Item – A single entry in an estimate representing a specific material, labor task or assembly. Detailed estimates may contain hundreds of line items for accurate cost tracking.

Lump Sum – A single fixed price for a complete scope of work, rather than itemized unit prices. Requires a comprehensive understanding of all included work.

M

Manifold – A fitting or pipe section with multiple outlets distributing water to several branch lines. Common in PEX plumbing systems, reducing fittings and potential leak points.

Markup – A percentage added to costs to cover overhead and profit. Typical markups range from 10-30% depending on company structure, project risk and market conditions.

Material List – A comprehensive listing of all materials required for a project with quantities, descriptions and pricing. Generated from the takeoff process.

P

P-Trap – A trap shaped like the letter P, standard under most fixtures for preventing sewer gas entry while allowing drainage. Estimated by size, with materials varying from PVC to chrome-plated brass, affecting cost.

Percent Complete – The portion of work finished at a given time, used in progress billing and schedule tracking. Accurate estimation of completion supports proper payment applications.

PEX (Cross-Linked Polyethylene) – A flexible plastic pipe for water supply systems. Reduces fittings and labor time compared to rigid pipe, significantly affecting installation costs.

Pitch – The slope of drainage piping, typically 1/4 inch per foot minimum. Proper pitch is essential for drainage and affects installation labor.

Plumbing Estimating Software – Software used by plumbing contractors to perform digital takeoffs, calculate material and labor costs, and generate accurate bids.

Plumbing Plan – A drawing showing the layout of plumbing systems, including fixtures, piping routes and equipment locations. Primary document for detailed takeoffs.

Pressure Reducing Valve (PRV) – A valve that automatically reduces high water pressure to a lower, safer level. Required when supply pressure exceeds 80 PSI, counted as an individual line item with installation labor.

Pressure Test – Testing plumbing systems for leaks using air or water pressure. Testing procedures affect the installation schedule and may require temporary caps and plugs.

Pricing – The process of assigning costs to takeoff quantities, combining material costs, labor rates and equipment expenses to determine total project cost.

Production Rate – The speed at which work is completed, typically expressed as units per hour or hours per unit. Accurate production rates are essential for competitive labor pricing.

Profit – The amount added to an estimate above all costs and overhead, representing the contractor's compensation for risk and business operation. Typically, 5-15% of the total cost.

Proposal – A formal document submitted to a potential client outlining scope, price and terms for performing work. The final product of the estimating process.

PVC (Polyvinyl Chloride) – A plastic pipe common in DWV systems and some water supply applications. Less expensive than metal alternatives with fast installation, reducing labor.

Q

Quantity Takeoff – The process of measuring and counting all materials required from the construction documents. The foundation of accurate estimating, typically performed from plans and specifications.

Quote – A price provided by a supplier or subcontractor for specific materials or services. Estimators collect and compare quotes to determine best pricing for estimates.

R

Riser – A vertical pipe carrying water upward. Measured and estimated separately from horizontal runs due to different hanger requirements and labor.

Riser Diagram – A schematic drawing showing the vertical arrangement of plumbing systems. Useful for understanding system layout and estimating vertical piping quantities.

Rough-In – The installation of supply, waste and vent piping before wall and floor finishes. Rough-in phase represents the majority of plumbing labor and materials.

S

Scale – The ratio between drawing dimensions and actual dimensions, such as 1/4" = 1'-0". Essential for accurate measurement during takeoffs.

Scope of Work – A detailed description of all work included in an estimate or contract. Clear scope definition prevents disputes and ensures accurate pricing.

Shop Drawing – A detailed drawing prepared by the contractor or fabricator showing how specific components will be manufactured or installed. May be required for complex systems, affecting schedule and coordination costs.

Specifications – Written requirements describing materials, installation methods and quality standards. Must be read carefully as they often supersede plan information and affect material pricing.

Stack – A vertical drainage or vent pipe. The main stack (soil stack) receives toilet waste while vent stacks provide air circulation.

Submittal – Documentation provided to the design team for approval before purchasing materials or equipment. Processing time affects the project schedule and must be considered in planning.

Sump Pump – A pump that removes water collected in a sump basin. Includes basin, pump, piping and electrical work with discharge to the appropriate location.

Supply House – A wholesale distributor of plumbing materials and fixtures. Estimators maintain relationships with supply houses to obtain competitive pricing and product availability information.

T

Tankless Water Heater – A water heater providing hot water on demand without a storage tank. More expensive initially but offering energy savings. Requires larger gas lines or electrical service, affecting costs.

Trap – A curved section of drainpipe holding water to prevent sewer gases from entering the building. Every fixture requires a trap, affecting material and installation counts.

Trim – The visible finished components of plumbing fixtures, including faucets, handles, escutcheons and drains. Often priced separately from rough-in valves, allowing finish selection timing flexibility.

U

Unit Price – The cost for a single unit of work, such as per linear foot of pipe or per fixture installed. Used in quantity-based estimating and change order pricing.

V

Value Engineering – The process of identifying alternative materials or methods that reduce cost while maintaining functionality. Often performed after initial estimates to meet budget targets.

Vent – Piping providing air circulation in drainage systems, equalizing pressure and preventing trap seal loss. A complete vent system is essential for proper drainage function.

W

Waste Factor – Additional material quantity added to account for cutting waste, damage and errors. Typical waste factors range from 5-15% depending on material type and installation complexity.

Water Closet – The plumbing industry term for a toilet. Estimated based on type (floor-mount, wall-hung), flush mechanism (gravity, pressure-assist) and water consumption.

Water Heater – A tank storing and heating water for domestic use. Major cost item specified by capacity (gallons), recovery rate, energy source (gas, electric, oil) and efficiency rating.

Water Service – The pipe delivering potable water from the public main or private source to the building. Includes excavation, pipe, fittings, corporation stop, curb stop and meter pit or installation.

---

Understanding this terminology will help plumbing estimators read plans accurately, communicate with contractors and engineers and produce detailed, competitive bids. For more information on plumbing estimating software and tools, visit McCormick Systems.