Window terminology for Phoenix homeowners

This is the vocabulary a glass company puts on a quote, translated. Read it before approving work on your windows and you will know what is being proposed, and where a quote describes something other than what you assumed.

It runs the way you would look at a window rather than alphabetically: the glass, the sealed unit behind fogging, the moving parts, the styles you see across the valley, the code rules, and last the one distinction that decides how much money is on the table. We have done this work in Phoenix since 2010, and these are the words we use daily.

What kinds of glass go into a house?

Five types cover almost everything in a Phoenix home, and the differences decide what happens when glass breaks, whether it can be cut on site, and how hot your living room gets in July.

• Annealed glass. Ordinary float glass, cooled slowly, not strengthened. It breaks into long curved shards. Why this matters to you: it is the least expensive glass and can be cut to size any time, but it is not permitted in a hazardous location. A window that broke into dangerous pieces and came back as annealed glass got the wrong product.
• Tempered glass. Annealed glass reheated to near softening and chilled hard at the surfaces, putting the faces in compression and the core in tension. It is several times stronger and breaks into small blunt cubes rather than blades. Why this matters to you: tempered glass cannot be cut, drilled or edged after heat treatment. Touch the edge with a tool and the whole pane lets go. So it has to be ordered to exact measured size, which is why replacing one takes a day or two rather than an hour. Look for the sandblasted stamp in a corner.
• Laminated glass. Two layers of glass with a plastic interlayer bonded to both. It cracks, but the pieces stay stuck to the film. Why this matters to you: a glazier can cut laminated glass on site by scoring both faces and parting the interlayer, so it is often a same visit job where tempered is not. It also cuts street noise and blocks nearly all ultraviolet, which is why it turns up on road-facing bedrooms and over furniture that keeps fading.
• Low-E glass. Glass with a microscopically thin metallic coating that reflects heat while passing visible light. Why this matters to you: in this climate it is the biggest comfort difference you can make to a west-facing room. The coating lives on one specific surface inside a sealed unit and goes back on that same surface when the unit is rebuilt, so a replacement ordered without matching the original will look slightly off next to the window beside it.
• Obscure and patterned glass. Textured, acid etched, reeded or frosted glass that passes light and blocks the view. Why this matters to you: these are named patterns from named makers, so a bathroom pane replaced with a merely similar texture reads as mismatched from the street. Photograph the pattern before anyone removes it.

What is an insulated glass unit, and why does one fog up?

An insulated glass unit, shortened to IGU, is two panes held apart by a spacer bar around the perimeter with a sealed air or argon gap between them. It is one manufactured assembly, not two windows, and not something anyone can open up and clean between.

The perimeter carries two seals doing different jobs, and that is the whole explanation for foggy windows:

• Primary seal. A thin band of polyisobutylene between the spacer and each pane. This is the moisture barrier, keeping water vapor out of the gap and, on argon filled units, keeping the gas in.
• Secondary seal. A structural bead of silicone or polyurethane around the outside of the spacer, holding the sandwich together and carrying the load as the glass expands and contracts.

Inside the spacer is a desiccant, a drying agent that absorbs the moisture sealed in at the factory. When the primary seal fails, outside air gets pumped in and out of the gap daily as Phoenix heat expands the trapped air and night cools it. The desiccant saturates, and after that every temperature swing condenses moisture on the inner faces of the glass.

Why this matters to you: the haze between the panes is the failed seal. Nothing can be cleaned or dried out for good, and the mineral staining that etches into the inner faces is why waiting makes it worse. The fix is a new sealed unit in your existing frame, which is our foggy window repair work is, and the same subject from the other direction is covered under dual pane glass.

What are the parts of a window called?

Most quote disputes come from two people using the word window differently. Here is the anatomy.

• Frame. The fixed outer structure attached to the house, aluminum on older Phoenix homes and vinyl on newer ones. It does not move, and replacing it is construction rather than glass work.
• Sash. The part holding the glass that moves. A slider has two, one fixed and one operating. Sash replacement on a quote means the panel, not the hole in the wall.
• Lite. The trade spelling of light, meaning one pane in an opening. A two lite slider has two panes. Ask how many lites and you have asked how many pieces of glass.
• Glazing bead or glazing stop. The removable strip holding glass into the sash, sometimes over a gasket or sealant. Taking it off correctly is how glass comes out without wrecking the sash. The vehicle equivalent people sometimes borrow is the pinch weld, the flange a windshield is bonded to. On a house it is the bead.
• Balance. A spring mechanism in the jamb of a hung window that counterweights the sash so it stays where you leave it. Block and tackle, spiral and constant force are the common types. Why this matters to you: a window that slams down or will not stay up has a failed balance and perfectly good glass, which is a small repair. That is the subject of window balance replacement.
• Roller. Small wheels in the bottom rail of a sliding sash or patio door, riding in the track. They are consumable, and grit and heat kill them.
• Track. The channel the rollers run in. A bent or worn track destroys new rollers within a season, so it gets checked before anything is fitted. Doors are covered under sliding door rollers.
• Weatherstripping. The fin, pile or bulb seal closing the gap between sash and frame. Here it hardens and crumbles under ultraviolet long before anything else, so a window that whistles or lets dust in needs this, not glass.
• Muntin and mullion. A muntin divides panes within one sash, the grid look, and on modern windows it often sits inside the sealed unit as a decorative grille. A mullion is the structural post between two whole window units joined side by side. Why this matters to you: people swap the words freely and should not. One is decoration, the other holds up part of your wall, so if a quote says mullion, ask which it means.

Which window styles are common in Phoenix homes?

Style decides what can break and what the repair involves. Four families cover the valley.

• Horizontal slider. One sash slides sideways past a fixed one. This is the most common style in Phoenix by a wide margin, standard in tract homes built here from the 1970s onward. Why this matters to you: a slider has no balances. Gravity is not fighting you, so rollers, track and weatherstripping are the failure points instead.
• Single hung and double hung. Sashes move up and down. Single hung means only the bottom sash operates, double hung means both do. Why this matters to you: these do have balances, one on each side of every operating sash, and a hung window that will not stay open is telling you which part failed.
• Casement and awning. Both hinge and crank open. A casement is hinged at the side and swings out like a door, an awning is hinged at the top and tilts from the bottom, so it can stay open in rain. Why this matters to you: the crank, the hinge arm and the lock linkage are what wear out on these, not the glass.
• Picture or fixed. A pane that does not open, either in its own frame or as the fixed half of a slider. Why this matters to you: nothing mechanical can fail, so the problem is always the glass or the seal, and it is the simplest swap in the house with no moving parts to reassemble.

If your home has single glazed windows the vocabulary shifts, and single pane glass covers what changes.

What is a hazardous location, and what is safety glazing?

Building code names certain positions hazardous locations, meaning a person could fall into the glass or walk through it. Glass there must be safety glazing, in practice tempered or laminated, carrying a permanent stamp.

The positions that come up most in Phoenix homes:

• Glass in a door, and the fixed panel beside a sliding patio door
• Any pane within a set distance of a door edge, where a stumble puts someone through it
• Glazing around tubs, showers, saunas and pools, measured from the standing surface
• Large panes whose bottom edge sits low to the floor, meaning most floor-to-ceiling glass
• Glass along stairs, landings and ramps

Why this matters to you: if a pane in one of those positions came out tempered, it goes back tempered. Not an equivalent, not a thicker piece of annealed, not a compromise because it is faster. Quoted for a shower pane or a patio door lite with no mention of tempered or safety glazing, ask directly. The corner stamp is the proof, so photograph it before the old glass leaves.

What is the difference between glass replacement and window replacement?

This one is worth more than all the rest put together, because it is where homeowners overspend.

Glass replacement means the frame and sash stay in your wall and only the glass changes: a broken pane out and a new one in, or a failed sealed unit swapped for one built to your measurements. No stucco is cut, no drywall opened, no trim pulled. Most jobs finish in one visit once the glass is in hand, with no repainting afterward.

Window replacement means the whole assembly comes out, frame included, and a new one goes in. That is construction. It touches stucco or siding, usually means new trim and paint, may need a permit, and costs several times what the same opening costs in glass.

Why this matters to you: a fogged dual pane, a cracked pane, a rock strike and a failed seal are all glass problems. The frame is doing its job. Being sold a new window for any of those is being sold construction to solve a glass fault. Frame replacement earns its keep when the frame is the problem, when aluminum has corroded through, when a sash has racked out of square beyond adjustment, or when you are changing the size or style of the opening. We tell you which one you are facing before you commit, and both paths are laid out on window repair and window replacement.

What terms show up on a written quote?

A few appear on paper rather than in conversation. Glazing as a verb means setting glass into a frame, so a glazier does it. U-factor measures heat passing through the whole assembly, lower being better. Solar heat gain coefficient, or SHGC, measures how much solar heat gets through, and a low number is what you want on west and south exposures. Argon fill is the inert gas some sealed units carry between the panes.

Retrofit or insert means a new window set into your existing frame. Full frame means everything out to the studs. Nail fin or stucco flange fastens a new construction frame to the sheathing beneath the stucco, which is why full frame work disturbs the exterior. If a quote uses a word you do not know, ask what it does rather than what it is called.

Common questions about window terms

Who decides whether my window needs tempered glass?

Building code does, based on where the pane sits rather than preference. Doors, glass beside doors, bathrooms, low glass and stairways are the usual hazardous locations. We note the position on the estimate and quote safety glazing where code calls for it.

Where can I find out what glass is already in my window?

Look in the corners of each pane for a small sandblasted or printed stamp naming the maker and the standard the glass meets. Tempered and laminated panes carry one. Plain annealed glass has none, which is itself an answer.

Can you cut tempered glass down to fit?

No. Cutting, drilling or grinding a tempered pane releases the stress in it and the whole piece breaks into cubes. It has to be made to size, so we measure, order, and fit it when it arrives. Laminated is the opposite case and can be cut on site.

Is a foggy window a broken window?

The glass is intact and the seal is not. Haze between the panes means the primary seal failed and the desiccant saturated, so the sealed unit gets replaced while your frame and sash stay in the wall. Glass job, not a window job.

What is the difference between a sash and a frame?

The sash holds the glass and moves. The frame is fixed to the house and does not. Most quote confusion we untangle comes down to one of those words being used for the other.

Do sliders have balances like hung windows do?

No. A horizontal slider moves sideways, so there is no weight to counterbalance and nothing in the jamb. If a slider drags, look at the rollers, the track and the weatherstripping. Balances belong to hung windows.

Does replacing one pane of a dual pane unit work?

Not as a repair. A sealed unit is one manufactured assembly, so both panes, the spacer and both seals go in together as a new unit built to your dimensions. Splitting the panes and resealing them in place does not last in Phoenix heat.

Where in the house does glass fail first in Phoenix?

West and south facing openings, which take the longest direct sun and the widest daily temperature swing. Seal failure shows up there years before the north side, and the weatherstripping on those same windows goes brittle first.

What should I have ready when I call for a quote?

The window style, how many panes are affected, whether the haze sits between the panes or the glass is cracked, and a photo of any corner stamp. Rough measurements help. We confirm every dimension before ordering, because a pane that arrives a quarter inch wrong is a wasted week.

Call (602) 777-3717 and describe what you are looking at in whatever words you have. We work out of 4202 E Elwood St #21, Phoenix, AZ 85040, Monday to Friday, 7:30am to 5:00pm, and serve homes across Maricopa County within a 50 mile radius. Our residential glass services page has the full picture, or go straight to sliding glass door repair if a patio door has stopped moving the way it should.

Which cities do we cover?

We work across the Valley, inside 50 miles of the shop on Elwood Street. Start with your city for what we see most in the housing stock there.

Two places the vocabulary matters most are the bathroom and the patio, where safety glazing is required: see glass shower doors and frameless shower enclosures.