Wafer board  

A manufactured wood panel made out of 1"- 2" wood chips and glue. Often used as a substitute for plywood in the exterior wall and roof sheathing.

Wainscot

Surfacing on the lower part of an interior wall when finished differently from the remainder of the wall. walk-in hood A fume hood designed to be floor-mounted with sash and/or doors closing the open face. 

Wall hydrant      

Wall hydrants protrude through the wall of a building or pump house.

Wall ladder 

A straight, single-section ladder used for placement against walls.

Wall sprinkler 

An automatic sprinkler system designed to protect a wall or an exposure area.

Wall tie  

Small metal strip or steel wire used to bind courses of masonry to wood frame in veneer construction.

Wallboard

Wood pulp, gypsum, or similar materials made into large rigid sheets that may be fastened to the frame of a building to provide a surface finish. 

Warm zone  

The area where personnel and equipment decontamination and hot-zone support takes place; includes control points for the access corridor and thus assists in reducing the spread of contamination; referrers to as the "decontamination," "contamination reduction," "yellow zone," "support zone" or "limited access zone" in other documents.

Warning devices 

Any audible or visual devices, such as flashing lights, sirens, horns, or bells, added to an emergency vehicle to gain the attention of drivers of other vehicles.

Warning lights

Lights on the apparatus designed to attract the attention of other motorists.

Wash down   

Flushing spilled combustible materials such as flammable liquids. In ,any instances, this procedure is not recommended as it spreads the contaminants into the storm sewers and water table. See clean water act.

Waste line 

Hose line that is tied off or otherwise secured and is used to handle water in excess of that being used during a relay operation. Also known as a Dump Line.

Waste pipe and vent 

Plumbing plastic pipe that carries waste water to the municipal sewage system.

Waste stack 

A vertical pipe in a plumbing system that carries the discharge from any fixture. 

Watch  

A period of time during which a firefighter is assigned to the communications center desk or to other duties.

Watch desk 

The central communications center desk or a fire station patrol desk.

Watch line       

A charged line or hose remaining at the scene of a fire with a detail of firefighters to guard against possible rekindling after the fire has apparently been extinguished.

Water board    

Water resistant drywall to be used in tub and shower locations. Normally green or blue colored

Water closet 

Another name for toilet.

Water curtain 

A row of outside sprinklers protecting a building from exposure to fires; may also be achieved by placing hose streams to protect exposures; a fan-shaped stream of water applied between a fire and an exposed surface to prevent the surface from igniting from radiated heat. See Wall Sprinkler.

Water distribution system

System designed to supply water for residential, commercial, industrial, and/ or fire protection purposes; delivered through a network of piping and pressure-developing equipment.

Water hammer  

Water hammer is a pressure surge or wave caused by the kinetic energy of water in motion when it is forced to stop or change direction suddenly. If the pipe is suddenly closed at the outlet (downstream), the mass of water before the closure is still moving forward with some force, building up a high pressure and shock waves. In domestic plumbing this is experienced as a loud bang resembling a hammering noise. Water hammer can cause pipelines to break or even explode if the pressure is high enough and therefore can damage everything from nozzles and hoses to hydrants and fire engine pumps.

Water meter pit (or vault)

The box /cast iron bonnet and concrete rings that contains the water meter.

Water reactive materials  

Substances, generally flammable solids, that will react in varying degrees when mixed with water or when they come in contact with humid air.

Water shuttle operation 

Method of water supply by which tenders/tankers continuously transport water between a fill site and the dumpsite located near the emergency scene.

Water solubility

The maximum amount of a substance that results when it is dissolved in water. 

Water supply   

Any source of water available for use in firefighting operations.

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Water supply pumper        

Pumper that takes water from a source and sends it to attack pumpers operating at the fire scene.

Water tank 

Water storage receptacle carried directly on the apparatus. NFPA 1901 specifies that Class A pumpers must carry at least 500 gallons (2000 L). Also called Booster Tank.

Water thief   

Any of a variety of gated valves or connections that permits supplying several smaller hose lines from a larger line; variation of a wye adapter has three gated outlets, usually two 1 1/2-inch (38 mm) outlets and one 2 1/2-inch (65 mm) outlet; a single inlet for 2 1/2-inch (65 mm) or larger hose.

Water tower       

An apparatus-mounted portable standpipe with one or more nozzles that can be elevated to variable heights; primarily intended for deploying an elevated master stream; not generally intended for climbing operations. Also known as an Elevating Master Stream Device.

Watergun  

A pressurized water fire extinguisher.

Waterway  

Path through which water flows within a hose or pipe.

Watt [W]

A unit of power in the International System equal to one joule per second. 

Waybill 

The shipping paper prepared by the railroad from a bill of landing. Waybills generally accompany a shipment and are carried by the conductor in the caboose of the train. A railroad document describing a shipment for materials being transported by rail showing the shipper, consignee, routing, and weights, used by the carrier for internal record and control, especially when the shipment is in transit.

Weather stripping

Strips of fabric or metal fastened around the edges of windows and doors to prevent air infiltration. 

Weatherization     

Work on a building exterior in order to reduce energy consumption for heating or cooling.  Work involving adding insulation, installing storm windows and doors, caulking cracks and putting on weather-stripping.

Weep hole 

Small holes in masonry cavity walls to release moisture accumulation to the exterior. 

Weep holes 

Small holes in storm window frames that allow moisture to escape.

Welded seam

A union made by welding; the joining of two or more pieces of material by applying heat, pressure, or both, with or without filler material, to produce a localized union through fusion or recrystallization across the interface

Well opening

A floor opening for a stairway. 

Wet down   

Wetting down or dampening down debris after fire has been controlled but not completely extinguished.

Wet pipe sprinkler system

An automatic sprinkler system in which the pipes are constantly filled with water under pressure.

Wet standpipe system

A building standpipe system constantly filled with water; sections of small diameter fire hose are connected to the standpipe system on each floor for use of occupants.

Wet water 

Water to which a wetting agent has been introduced to reduce the surface tension of the water and to improve its penetration qualities. Trade name for a 3-M wetting agent product.

Wet barrel hydrant 

Fire hydrant that has water all the way up to the discharge outlets; may have separate valves for each discharge or one valve for all the discharges; used in areas where there is no danger of freezing weather conditions.

Wetting agent 

Chemical solution added to water to reduce its surface tension and improve its penetrating ability; detergent is a mild form of wetting agent; Class A foams have strong wetting properties and can be used as wetting agents at 0.1 to 0.3 percent. See wet water

Wheel blocks

Wedge shaped wooden or metal blocks placed against the wheels of an apparatus to prevent its movement. See Chocks.

Wild line 

A charged hose line with water flowing and that is not under control.

Wildfire

A fire, naturally caused or caused by humans, that is not meeting land management objectives. 

Wildland fire apparatus  

A fire apparatus that is de- signed especially for use in fighting wildland fires. See Initial Fire Attack Apparatus and Brush Pumper.

Wildland-Urban Interface Zone  

Where structures and other human developments meet, or intermingle with, undeveloped wildlands.

Winch

Pulling tool that consists of a length of steel chain or cable wrapped around a motor-driven drum; most commonly attached to the front or rear of a vehicle.

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Wind bracing  

Metal straps or wood blocks installed diagonally on the inside of a wall from bottom to top plate, to prevent the wall from twisting, racking, or falling over "domino" fashion.

Winder 

Stair tread that is wider at one end than the other, allowing the stairs to change direction. 

Window buck

Square or rectangular box that is installed within a concrete foundation or block wall. A window will eventually be installed in this "buck" during the siding stage of construction

Window frame

The stationary part of a window unit; window sash fits into the window frame.

Window sash 

The operating or movable part of a window; the sash is made of window panes and their  border.

Wire cutters

A tool with approved, insulated handles, used to cut wire.

Wire nut      

A plastic device used to connect bare wires together.

Wired glass    

Glass with a mesh-wire pattern in it, used to resist heat or to protect openings against the spread of fire. See Skylight.

WMD 

Weapons of Mass Destruction

Wonderboard ™ 

A panel made out of concrete and fiberglass usually used as A ceramic tile backing material. Commonly used on bathtub decks.

Worker       

A fire that requires a major fire fighting effort to extinguish. Also called a Working Fire

Working Fire

A fire of sufficient magnitude to require the services of all firefighters responding to it as opposed to an alarm that does not require a full assignment (i.e., trash fire, car fire, etc.). Often referred to by firefighters as a "real" fire or "worker."

Woven jacket hose 

Fire hose constructed with one or two outer jackets woven on looms from cotton or synthetic fibers.

Wrapped drywall   

Areas that get complete drywall covering, as in the doorway openings of bifold and bypass closet doors.

Wye 

A hose appliance for the purpose of dividing one line into two or more working lines; normally has two male and one female couplings and is usually gated; older style wye's can be found non-gated.

Wyth     

A continuous vertical section of masonry one unit in thickness