---
title: "Window and Door Glossary: 40 Terms Defined | Honey Rock Window and Door"
description: "Plain-English definitions of 40 window and door terms, from SHGC and U-factor to pivot hinges and thermal breaks, with sources where numbers are given."
url: https://honeyrock.multisites.ai/glossary
publisher: Honey Rock Window and Door
phone: +1-214-484-9982
quote: https://honeyrock.multisites.ai/contact-us
---

# Glossary

40 window and door terms in plain English.

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## A

[Air leakage rating](https://honeyrock.multisites.ai/glossary/air-leakage-rating)

The air leakage rating shows how much air passes through a closed window or door, measured in cubic feet per minute per square foot. Lower is tighter.

[Aluminum-clad](https://honeyrock.multisites.ai/glossary/aluminum-clad)

Aluminum-clad describes a wood window or door whose outside face is covered with a layer of aluminum that resists weather and fading.

[Argon gas fill](https://honeyrock.multisites.ai/glossary/argon-gas-fill)

Argon gas fill replaces the air between the panes of an insulated glass unit with an inert gas that slows heat transfer.

[Awning window](https://honeyrock.multisites.ai/glossary/awning-window)

An awning window is hinged at the top and opens outward from the bottom, like a shade over the glass.

## B

[Bifold door](https://honeyrock.multisites.ai/glossary/bifold-door)

A bifold door has hinged panels that fold flat and stack to one or both sides of the opening.

## C

[Casement window](https://honeyrock.multisites.ai/glossary/casement-window)

A casement window is hinged on one side and swings outward like a door, usually with a crank.

[Certificate of Appropriateness](https://honeyrock.multisites.ai/glossary/certificate-of-appropriateness)

A Certificate of Appropriateness is City of Dallas approval for exterior work on a landmark or in a landmark district, issued before the work starts.

[Corner window](https://honeyrock.multisites.ai/glossary/corner-window)

A corner window joins two glass units at a corner with no post, so the view wraps around the room.

## E

[Egress](https://honeyrock.multisites.ai/glossary/egress)

Egress is a window or door opening large enough, and easy enough to open, that a person can escape through it in an emergency.

[ENERGY STAR climate zone](https://honeyrock.multisites.ai/glossary/energy-star-climate-zone)

An ENERGY STAR climate zone is a region of the country with its own limits for the U-factor and SHGC a window must meet to qualify.

## F

[Fixed (picture) window](https://honeyrock.multisites.ai/glossary/fixed-window)

A fixed window does not open. It gives the largest clear view and the thinnest frame for its size.

[Flashing](https://honeyrock.multisites.ai/glossary/flashing)

Flashing is waterproof material, such as metal or tape, that directs water away from the edges of a window or door opening.

[French door](https://honeyrock.multisites.ai/glossary/french-door)

A French door is a pair of glazed, hinged doors that open from the center with no post between them.

## I

[IGU (Insulated Glass Unit)](https://honeyrock.multisites.ai/glossary/igu)

An insulated glass unit, or IGU, is two or more glass panes held apart by a spacer and sealed around the edge with an air or gas space between.

[Impact-resistant glass](https://honeyrock.multisites.ai/glossary/impact-resistant-glass)

Impact-resistant glass is laminated glazing built to stay in the frame after a hard strike, such as hail or windborne debris.

## J

[Jamb](https://honeyrock.multisites.ai/glossary/jamb)

The jambs are the vertical side parts of a door or window frame. The head jamb runs across the top.

## L

[Laminated glass](https://honeyrock.multisites.ai/glossary/laminated-glass)

Laminated glass bonds two panes around a plastic interlayer, so the glass cracks but stays in one piece instead of falling out.

[Lift-and-slide door](https://honeyrock.multisites.ai/glossary/lift-and-slide-door)

A lift-and-slide door has a handle that lifts the panel off its seals so it glides easily, then lowers to lock tight.

[Low-E coating](https://honeyrock.multisites.ai/glossary/low-e-coating)

A low-E coating is a thin, nearly invisible metal layer on glass that reflects heat while letting daylight through.

## M

[Mullion](https://honeyrock.multisites.ai/glossary/mullion)

A mullion is the vertical or horizontal bar that joins two window or door units side by side or stacked.

[Multi-slide door](https://honeyrock.multisites.ai/glossary/multi-slide-door)

A multi-slide door has several large panels that slide past each other or tuck into a wall pocket to open a whole wall.

[Muntin](https://honeyrock.multisites.ai/glossary/muntin)

A muntin is a slim bar that divides one pane of glass, or one sash, into smaller panes called lites.

## N

[NFRC label](https://honeyrock.multisites.ai/glossary/nfrc-label)

The NFRC label is the sticker on a window or door that shows independently rated U-factor, SHGC, visible transmittance, air leakage and condensation resistance.

## P

[Pivot door](https://honeyrock.multisites.ai/glossary/pivot-door)

A pivot door turns on a hinge point set in the floor and head instead of side hinges.

[Pivot hinge](https://honeyrock.multisites.ai/glossary/pivot-hinge)

A pivot hinge is the hardware at the top and bottom of a pivot door that carries its weight and sets its swing.

## R

[Rough opening](https://honeyrock.multisites.ai/glossary/rough-opening)

The rough opening is the framed hole in the wall, before trim, where a window or door is set.

## S

[Sash](https://honeyrock.multisites.ai/glossary/sash)

The sash is the movable frame that holds the glass in a window. On a fixed window, it is the frame around the glass.

[SHGC (Solar Heat Gain Coefficient)](https://honeyrock.multisites.ai/glossary/shgc)

SHGC is a number from 0 to 1 that shows how much of the sun's heat passes through a window. A lower number blocks more heat.

[Sightline](https://honeyrock.multisites.ai/glossary/sightline)

A sightline is the visible width of frame, sash or bar you see between the glass and the wall; slimmer sightlines mean more glass and more view.

[Sill](https://honeyrock.multisites.ai/glossary/sill)

The sill is the bottom horizontal part of a window or door frame. It sheds water away from the opening.

[Slim-profile (thin-frame) window](https://honeyrock.multisites.ai/glossary/slim-profile-window)

A slim-profile window uses very narrow frames and sashes to maximize the glass area and the view.

[Storm rating (windborne debris)](https://honeyrock.multisites.ai/glossary/windborne-debris-rating)

A windborne debris rating shows that a window or door passed a test for resisting flying debris and pressure from high winds.

## T

[Tempered glass](https://honeyrock.multisites.ai/glossary/tempered-glass)

Tempered glass is heat-treated to be stronger than ordinary glass, and when it breaks it crumbles into small, blunt pieces instead of sharp shards.

[Thermal break](https://honeyrock.multisites.ai/glossary/thermal-break)

A thermal break is an insulating barrier built into a metal frame so heat cannot flow straight through the metal.

[Thermally broken steel](https://honeyrock.multisites.ai/glossary/thermally-broken-steel)

Thermally broken steel is a steel window or door profile with a built-in insulating barrier, so it keeps slim lines and better efficiency.

[Tilt-and-turn window](https://honeyrock.multisites.ai/glossary/tilt-and-turn-window)

A tilt-and-turn window opens inward two ways: tilted from the top for air, or swung open like a door.

## U

[U-factor](https://honeyrock.multisites.ai/glossary/u-factor)

U-factor measures how fast heat flows through a window or door. A lower number means better insulation.

## V

[Visible transmittance (VT)](https://honeyrock.multisites.ai/glossary/visible-transmittance)

Visible transmittance, or VT, is a number from 0 to 1 that shows how much daylight passes through a window. A higher number is brighter.

## W

[Warm edge spacer](https://honeyrock.multisites.ai/glossary/warm-edge-spacer)

A warm edge spacer is the low-conductivity strip at the perimeter of an insulated glass unit that cuts heat loss and lowers the chance of condensation.

[Wood-clad window](https://honeyrock.multisites.ai/glossary/wood-clad-window)

A wood-clad window has a real wood interior and a metal or other protective cladding on the outside that shields the wood from weather.

![A modern home with wide glass doors lit warm at dusk beside a pool](https://honeyrock.multisites.ai/_astro/dusk-modern-home-pool-01.CeePxgPr_Z2giQin.webp)

## Let’s frame your view.

Send your plans or a few photos of the openings. We will help you choose the system, the brand and the glass.

[Start your project](https://honeyrock.multisites.ai/contact-us)[or call (214) 484-9982](tel:+1-214-484-9982)