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This page will contain a glossary of terms and definitions relevant to the professional window cleaner. If you think we are missing a word or don't see something, please scroll down to the bottom of the page and submit it. If we think it will be helpful for others we will add it to the page.


Alpha Brush: A term used to refer to any waterfed brush that features a swivel gooseneck and over the top rinse bar.

Angle Adaptor (WFP): Connects the waterfed pole to the brush.

Apron: Inside flat trim member, which is used under the stool at the bottom of the window.

Astragal (Sp.): The center member of a double door, which is attached to the fixed or inactive door panel.

Awning: A window with a sash that is hinged at the top or topsides and opens/swings outward at the bottom.



Bay window: A composite of three or more windows, usually made up of a large center unit and two flanking units at 30°, 45°, or 90° angles to the wall. 90° angled window assemblies are often referred to as “Box Bay” windows (1.e. It looks like a box in plan view).

Boars Hair (WFP): Bristles on a waterfed brush are all-natural real Boars Hair. These provide a more aggressive scrubbing power and can generally clean with fewer passes. Heavier than Nylon bristles. Ideal for cleaning less than 30′ or 3 stories. Best for first time or irregular cleans.

Bow window: A composite of two or more window units in a radial or bow formation. These window configurations are often installed in a 10° angle to the exterior wall surface (i.e. it looks like a bow in plan view).

Brick mould: Outside casing around window to cover jambs and through which nails are driven to install the window. Traditionally used in masonry construction such as stone or brick, the decorative trim or molding surrounding the head and sides of the window frame was known as brick mold (brickmold, brickmould, brick moulding, etc.)

Bucket Bob: A playful term describing someone who has no intention of growing and regularly servicing a customer base but rather they just want to make some quick cash. Most often does not have a business license, insurance or may be operating under the table/radar.

Bucket On A Belt: Also referred to as "BOABs" or "hip buckets." These buckets can be attached to your belt so you can keep a selection of tools by your side. Can come in different clip styles such as semi-detachable, detachable or fixed clip. Generally used for holding squeegees, scrubbers and other small tools.

Butyl (butyl tape): A pliable substance applied between the window sash and the lights of glass to seal against the elements and typically used to adhere the glass to the sash.



Callback: A request you receive after service has been completed, either to fix something not done right or to explain a question regarding the service.

Carbon Fiber (WFP): Type of waterfed pole material. Top recommended material for professionals due to it being lightweight and stiff. Safe for use up to 60 feet.

Carbon Sediment Filter: In waterfed cleaning, this helps prevent material and debris from entering your RO membrane, as well as Chlorine.

Casing: Inside casing is a flat, decorative molding which covers the inside edge of the jambs and the rough openings between the window unit and the wall. Outside casing (or Brick Mould) served the same purpose, while it also is an installation device through which nails are driven to install the window unit to the wall.

Check rail: On a double-hung window, the bottom rail of the upper sash and the upper rail of the lower sash, where the lock is mounted. The rail sections of the top and bottom sash of a double-hung window where they meet in the middle, when in a closed position.

Clamp (WFP): The device used at the end of each section of a waterfed pole used to hold the section above it. Locks the pole in place upon extension. A complete clamp consists of a bolt (sometimes 2 bolts), lever, and clamp body.

Closeout: the final stroke when finished fanning a window pane

Clerestory: A window near the top of an outside wall. A window installed in a high location on a wall and generally out of common reach for operable purposes. These windows often use remote operation, such as electric motors or extension pole cranks, or they can simply be fixed or stationary windows.

Commercial Window Cleaning: Window cleaning that focuses on properties that are places of business such as shops, stores, offices, schools, dealerships, hospitals etc.

Construction Clean Up: Also referred to as "CCU." A type of job/ client. New constructions of houses or retail require windows be cleaned of all construction debris such as paint splatter & overspray, concrete splatter, mineral deposits, tape and glue residue, etc.

Cottage double-hung: A double-hung window in which the upper sash is shorter than the lower sash.

Cripples: The short 2’ x 4” members used to frame under the still or above the surface of the header in a rough opening for a window in a frame wall.

Curb: A watertight wall or frame used to raise slope glazing above the surface of the roof as a preventative measure against water leakage from melting snow or rain run-off.



Detailing: The use of a dry towel or cloth to wipe leftover water after the squeegee is done.

DI: Stands for Deionization, also referred to as "1-Stage" filtration

Deionization Resin: What many window cleaners use to “Purify Water.” It can be used as a standalone filtration system or as the final step in a multistage purification system.

Dormer: A space that protrudes from the roof, usually including one or more windows.

Double rafter: The doubling (side by side) of the roof members to reinforce an opening in the roof for a sloping glazing installation.

Double glazing: Use of two panes of glass in a window to increase energy efficiency and provide other performance benefits.

Drip cap: A moulding placed on the top of the head brick mould or casing of a window frame to deflect water away from the window. This is generally a metal flashing material.

Dual RO: An RODI purification system which has 2 RO membranes, instead of one. This increases flow output to the brush, allowing for greater heights to be reached without a pump, for dual users on the same system and for faster rinse times.



End Defender (WFP): A small ring of metal or plastic installed at the base of a waterfed pole section to protect the carbon fiber.

Extension Pole: Allows the user to attach traditional tools such as squeegees, scrapers or any other window cleaning accessories. Used for residential, route or storefront window cleaning.



Fabricating Debris: The result of the process of manufacturing heat strengthened or tempered glass. This type of glass must be cut to size before entering the tempering furnace. If it is not cleaned properly of glass fines or other airborne contaminants before the tempering process these can fuse to the surface of the window. These defects can cause scratching of glass surfaces when standard cleaning techniques are used.

Fanning: A technique used by a window cleaner where the squeegee is drawn back and forth across the surface being cleaned without lifting the tool off the glass. Also known as the “Snake” or “s curve technique” by some.

Fan Jets (WFP): Fan jets emit a fine mist of water over a larger area.

Fenestration: An architectural term referring to the arrangement of windows in a wall.

Finger-jointing: A means of joining individual pieces of wood together to form longer lengths. The ends of the pieces are machined to form a set of interlocking fingers, which are then coated with adhesive and meshed together under pressure.

Fixed: Non-venting or non-operable. Fixed windows are often referred to as Stationary or Picture windows.

Flashing: A metal or plastic strip attached to the outside of the head or side jambs to provide a weather barrier, preventing leakage between the frame and the wall. (See Drip Cap)

French hinged door: Hinged door(s) that have wider panel members around the glass.

French sliding door: A sliding door that has wider panel members around the glass., giving the appearance of a French hinged door.



Gasket: A pliable, flexible continuous strip of material used to affect a watertight seal between sash and frame of roof windows much like the seal around a refrigerator door.

Glass Sealant: Forms a protective barrier against smears, scratches and other damage. Applying a glass sealant reduces the amount of maintenance and prolongs the life of the glass.

Glazing: The glass panes or lights in a sash of a window. Also the act of installing lights of glass in a window sash.

Glazing bead: A plastic or wood strip applied to the window sash around the perimeter of glass.

Glazing compound: A pliable substance applied between the window sash and the lights of glass to seal against the elements and sometimes adhere the glass to the sash.

Glazing stop: The part of the sash or door panel that hold the glass in place.

Gooseneck: In relation to waterfed pole cleaning, the part that screws into the pole tip and also screws into the brush block. They come fixed or adjustable in angle. They can range in length from a couple of inches to many feet.



Hard Water: Water that has high mineral content, full of minerals like calcium, magnesium, metal cations, and compounds such as sulfates and bicarbonates. When hard water comes in contact with glass, it can leave behind mineral stains.

Head: The main horizontal member forming the top of the window or doorframe. 

Head board: A flat board cut to fit the contour of a bow or bay window and installed between head jambs and the flat wall surface to finish that area which would normally be ceiling.

Header: A heavy beam extended across the top of the rough opening to prevent the weight of the wall from resting on the window or door frame.

Hopper: A window with a sash that swings inward. Specifically - the sash is hinged at the bottom or bottom-sides and opens/swings inward at the top (opposite of an awning window). These window types were often used in school buildings.

Hose (WFP): Feeds purified water to your waterfed pole brush.

Hybrid (WFP): Type of bristles on a waterfed brush. Bristles are a mix of Nylon & Boars Hair

Hydrophilic Glass: Lit. - "water loving". A term used to describe glass where water "sheets' down the pane when water-fed cleaning. This results in faster rinse times.

Hydrophobic Glass: A term used to describe glass where water "streams" down the pane when water-fed cleaning. This results in longer rinse times.





Jack stud: Framing members, generally 2" x 4"s which form the inside of the window or rough opening. They run from the sole to the header, which is supported by them.

Jamb liner: Metal or plastic covering the surface and head jambs of sliding window.



Keeper: The protruding, hook-shaped part of a casement window lock, which is mounted on the inside surface of the sash stile. This is also used for the locks on other window types, and is simply the female part of the lock which is engaged by the male or rotating part of the window lock.



Lift (Sash Lift): A handle or grip installed on the bottom of the rail of the lower sash of a double-hung window to make it easier to raise or lower the sash.

Light: (also spelled lite) Glazing framed muntins and/or sash in a window or door.

Light shaft: An insulated shaft built to direct the light from a roof window or skylight through the attic to the room below.

Low-E glass: A common term used to refer to glass that has low emissivity due to a film of metallic coating on the glass or suspended between the two lights of glass to restrict the passage of radiant heat.



Masonry openings: The openings in a masonry wall to accept a window or door unit, the same as a rough opening in a frame wall.

Modularscopic (Mod-scopic) Section: A section of a waterfed pole which is attached to the bottom when the pole is fully extended against the building. Combines the features of a Telescopic pole with modular sections. Pole sections fit inside one another but sections can also be added on later to gain additional height. Generally used with poles over 40'.

Mortise: A slot or rectangular cavity cut into a piece of wood to receive another part.

Mortise-and-tenon: a strong wood joint made by fitting together a mortise in one board and a matching projecting member (tenon) in the other.

Mullion:  The vertical or horizontal divisions or joints between single windows in a multiple window unit.

Mullion casing: An interior or exterior casing member to cover the mullion joint between single windows.

Muntin: A short bar used to separate glass in a sash into multiple lights. (Also called a windowpane divider or a grille.)



Non-Proprietary Filters (WFP): Filters that can be sourced or bought from multiple vendors or even locally.

Nylon (WFP): Also referred to as "Monofilament." Nylon bristles are soft plastic materials that are gentle. Lighter and not as aggressive as Boar's Hair bristles. Best for working at any height and regular maintenance cleans.



Operator:  A metal arm and gear that allows for easy operation or closing or projecting windows.

Outer frame member: The exterior protruding portion of a window frame that has no exterior casing.



Palladian window: A large, archtop window flanked by smaller windows on each side.

Panel: This usually refers to the separate panel or panels in a door frame.

Passive solar collector: Any glazed area in the walls or roof of a building pointed to the south to take maximum advantage of the sun’s heat without a mechanical (or active) method of storage or distribution of the heat.

Pencil Jets (WFP): Pencil jets emit a small, circular jet of water.

Picture frame casing: The use of casing on all four slides of the interior of a window, replacing the stool and apron at the sill. Also known as full-bound casing.

Pitch: The pitch of a roof is the degree of the inclination upward from horizontal or flat. It may be expressed in degrees or as the ratio of the number of inches it rises in each 12 inches or horizontal span; 4/12 means the roof rises four inches in every foot span.

Pivot: A mode of operation for ventilating windows, which generally means the sash, pivots on a central axis and turns 90 or more degrees.

Proprietary Filters (WFP): These types of filters typically cost more and you are limited to purchasing from one particular vendor. 

Pure Water: Water that has been "purified" and has a TDS of zero (0).





Rafter: Structural members of a roof that support the roof and run from the ridge to the eaves (overhang).

Rails: The horizontal members of a window sash or door panel.

Residential Window Cleaning: Any window cleaning done on a residence such as a home, apartment, condo, townhouse, flat etc. Service provided to end customer on-site.

Reverse Cottage double-hung: A double-hung window in which the upper sash is taller than the lower sash.

Rinsebar: A device installed on the back of a waterfed pole brush, which allows a small stream of water to cascade over the top of the brush. Allows brush to remain on the glass during the final rinse. Essential for Skylights, solar panels, and 2nd story work and above.

RO Membrane: In place to prolong the life of your DI Resin in a multistage waterfed system. Removes up to 90% – 95% off all Total Dissolved Solids. If your incoming TDS is above 100 it is typically more cost-effective to use a multistage system with an RO membrane attached.

RODI: Stands for Reverse Osmosis Deionization, also referred to as "3-Stage" filtration in waterfed window cleaning.

Rough opening: The opening left in a frame wall to receive a window or door unit.

Rough sill: The horizontal rough framing member, which forms the bottom of the rough opening. It is toenailed into the jack studs and is supported by cripples.



Sash balance: A system of weight, cords, and/or coiled springs which assist in raising double-hung sash and tend to keep the sash in any placed position by counterbalancing the weight of the sash.

Sash cord: In double-hung windows, the rope or chain that attaches the sash to the counter balance.

Sash lock: Generally, a cam-action type lock applied to the check rails of a sliding window or at the open edges of a projecting window to pull the check rails tightly together or to seal the sash tightly to the frame, both for security and weather tightness.

Sash weights: In older double-hung windows, the concealed cast-iron weights that are used to counterbalance the sash.

Scrapers: Specialty tools with blades used to remove the stubborn buildup of dirt. Vary in design, for example: angled or straight.

Screen Cleaner: A portable device attaches to a common garden hose and consists of a frame with built-in brushes and running water. Dirty window screens are inserted into and scrubbed and rinsed clean.

Seat board: A flat board cut to fit the contour of a bow or bay window and installed between the sills and the flat wall surface, providing a seat or shelf space.

Shims: Wood wedges (often wood shingles) used to secure the window or door unit in a rough or masonry opening in a square, level and plumb position during and after installation.

Side lights: Tall, narrow, fixed or operating sash on either or both sides of a door to light an entryway or vestibule.

Sill: Horizontal member that forms the bottom of a window frame.

Sill course (soldier course, soldier row): The row of brick, cement blocks or stones set into a pattern across the bottom of a masonry opening which lie under the outside edge of the window sill. The pattern is commonly shown as bricks set in an upright position and tightly grouped (visually appearing as a row of soldiers standing in formation).

Sill Nosing: The trim or molding located at the bottom exterior sill area of the window frame in a masonry wall. It is used in combination with brick molding (i.e. brick mold is located at the head and sides, with still nosing at the bottom.

Simulated divided light: A method of constructing windows in which muntins are affixed to the inside and outside of a panel of insulating glass to simulate the look of true divided light.

Single glazing: Use of single panes of glass in a window. Not as energy-efficient as double-glazing.

Single-hung: A double-hung type of window in which the top-sash is fixed or inoperable.

Slope glazing: Any glazed opening in a sloped roof or wall, such as a stationary skylight or fully operable roof window.

Solar gain: The process of providing a net heat gain within a structure, over and above the normal heat loss, by passive collection of the sun’s heat through windows and other glazed areas.

Sole plate: The bottom horizontal member in a frame wall. Usually either single or double 2” x 4”s. It is nailed to the deck or rough floor and the studs are nailed to it.

Stile: The vertical side member of a window sash or door panel.

Stool: Inside horizontal trim member of a window or sash.

Stop: A wood I trim member of a window nailed to the window frame to hold, position, or separate window parts. The stop is often moulded into the jamb liners on sliding windows.

Storefront Window Cleaning: Usually one story (maybe 2 stories, like a car dealership or entrance to an establishment) work that goes on a frequency of at least once a month.

Storm Windows: Windows held in a frame that is secured (usually) over older single-pane windows to increase energy efficiency. This doubles the number of panes in the opening.

Stud: Vertical wood framing members which form a frame wall. In normal construction, these are 8 foot long 2” x 4”s.

Squeegee: A tool designed to remove water, soap solution and dirt from a flat pane of glass. Consists of a handle, a channel, and a rubber.

Swivel Gooseneck: A gooseneck that allows the brush to pivot side-to-side.



TDS: Stands for "Total Dissolved Solids" and is a simple measurement of water quality. This metric is used to measure levels of solids and impurities (minerals, metals) in water.

TDS Meter: A device used to measure the TDS levels in the water.

Telescopic Pole: Refers to a waterfed pole in which all the sections nest into each other when fully collapsed. Pole sections fit inside of one another. Open a clamp and extend a section to gain height.

Tenon: A rectangular projection cut out of a piece of wood for insertion into a mortise.

Traditional Window Cleaners: Traditional window cleaners favor using hand tools like squeegees and mops.

Transom: A smaller window above a door or another window. A transom joint is also the horizontal joining area between two window units that are stacked one on top of the other.

Triple glazing: A sash glazed with three lights of glass, enclosing two separate air spaces.

True divided light: A term that refers to windows in which multiple individual panes of glass or lights are assembled in the sash using muntins.



U-Factor: A measure of heat transmission through a wall or window. The lower the U-Factor, the better the insulating value. The U-factor is the inverse of its R-value, a more familiar term describing thermal resistance or insulation.

Unison lock: A casement locking system that secures the window at two locking points by operation of one handle.



Vapor barrier: A watertight material used to prevent the passage of moisture (i.e. water vapor) into or through floors, walls and ceilings.

Venting unit: A window or door unit that opens or operates.



Washer Sleeve: Also referred to as a "mop" or "sleeve." These covers refer to the scrubbing agents attached to a T-Bar.

Waterfed Brush: The device found at the end of a waterfed pole used to abrade the glass and loosen dirt. They are available in Nylon, Boar's Hair or hybrid, which is a mix of the two. Consists of a brush block, jets, bristles, backing plate.

Waterfed Pole: Also referred to as "WFP" and delivers water to clean windows. Allows you to clean ground-level windows all the way up to 6 stories from the ground. Can be made of Aluminum, Fiberglass, or Carbon Fiber material. Can be suited for residential, commercial and more.

Window Cleaning: The act of washing or cleaning glass windows and surfaces to remove dust, dirt and other substances.

Windload: Force exerted on a surface by moving air.

Window Bleed: Water that runs from the top of a window or from vinyl lettering, stickers, etc on the window after it has been cleaned, caused by using to much water or no detailing.

Windowpane divider: A short bar used to separate glass in a sash into multiple lights. Also called muntin or a grille.



XERO: Pronounced "zero", WCR's house brand of waterfed poles, systems, and other professional window cleaning equipment