Every term on an estimate, in plain English.

How much heat passes through a window: the lower the U-factor, the better it holds heat in. It is the one number worth comparing when you are choosing between window brands and styles.

Denver Metro note What counts as efficient enough varies by area, and Denver Metro has its own version of this rule.

How much of the sun's heat comes through the glass into the room. A lower SHGC blocks more heat, which matters most on windows that sit in direct afternoon sun in a warm climate.

Denver Metro note What counts as efficient enough varies by area, and Denver Metro has its own version of this rule.

A microscopically thin metallic layer on the glass that reflects heat while still letting daylight through. It is what makes a window energy efficient without tinting the glass or darkening the room.

Denver Metro note What counts as efficient enough varies by area, and Denver Metro has its own version of this rule.

An inert, odorless gas sealed between the panes of an insulated glass unit in place of ordinary air. It is denser than air and slows heat moving through the glass, adding a bit more insulating value.

The sealed glass assembly inside a window: two panes, called double pane, or three, called triple pane, held apart by a spacer and sealed airtight. More panes and a wider gap between them insulate better.

When the seal on an insulated glass unit lets go and moisture gets between the panes, leaving a permanent haze that cleaning cannot remove. It usually means the glass, not the whole window, needs replacing.

Moisture that forms on glass when warm, humid indoor air meets a cold surface. Condensation on the room side of the glass is normal in cold weather; condensation trapped between the panes means the seal has failed.

Glass heat-treated to be far stronger than ordinary glass, and if it does break it crumbles into small, blunt pieces instead of sharp shards. Used near floors, doors, and other spots where someone could fall into it.

Two layers of glass bonded around a clear plastic interlayer, so the glass stays in one piece and in the frame even after it cracks. Common in storm-prone areas for the impact resistance it adds.

How much daylight passes through the glass and into the room, shown as a rating on the window label. A higher number means a brighter room, weighed against how much heat a homeowner wants blocked.

ENERGY STAR is a voluntary label a window can earn by meeting efficiency targets set for its region. The IECC is the model energy code many local governments adopt, and it can set the minimum window performance required on a project.

Denver Metro note What counts as efficient enough varies by area, and Denver Metro has its own version of this rule.

Both have an upper and lower sash in one frame. On a double-hung, both sashes slide up and down; on a single-hung, only the bottom sash moves while the top stays fixed in place.

Both crank open on hinges instead of sliding. A casement swings outward from the side like a door; an awning hinges at the top and opens outward from the bottom, so it can stay open in light rain.

A window with one or more sashes that slide side to side in a track rather than swinging open. Simple, gives a wide opening, and has fewer moving parts than a crank-operated window.

A large fixed window that does not open at all, built for the view and the light rather than airflow. Often flanked by operable windows on either side to still get ventilation.

Both project outward from the wall to add space and light. A bay window is three windows set at angles; a bow window uses four or more panels curved into a gentler arc.

A window sized and placed to serve as an emergency exit, most often required in a bedroom. It needs a minimum opening size and a maximum height off the floor, which can rule out some styles in a basement.

Windows built in shapes other than a standard rectangle, such as arches, circles, half-rounds, and octagons. Usually fixed rather than operable, and often placed above a door or another window as an architectural detail.

A frame made of PVC, the most common material sold today. Low maintenance and never needs painting, though it can expand and contract more than other frame materials across a big temperature swing.

Fiberglass frames are pultruded from glass fibers and resin; composite frames blend wood fiber or other materials with a polymer. Both hold paint well, resist rot, and move less with temperature than vinyl.

A wood frame with a protective layer, usually vinyl, aluminum, or fiberglass, bonded to its exterior face. Gives the look and feel of real wood on the inside with less outdoor upkeep than bare wood.

A metal frame, thin and strong for its size, common on older homes and some commercial-style windows. Conducts heat and cold more readily than other frame materials unless it has a thermal break built in.

A retrofit, or insert, replacement fits a new window into the existing frame left in the wall. A full-frame replacement removes everything down to the rough opening, which lets a crew fix rot or settling hidden underneath.

A nailing fin is the flange around a new-construction window that gets nailed to the sheathing; flashing tape laps over the fin afterward to seal that seam against water. Both matter as much to a leak-free install as the window itself.

A shaped pan set into the rough opening at the bottom of a window before the window goes in. It catches any water that gets past the window and carries it back outside instead of into the wall.

Capping wraps exterior wood trim in aluminum or vinyl so it never needs repainting again. Brickmold is the trim piece that finishes the gap between a window frame and the wall or brick around it.

The jamb is the frame's side and head pieces; the sash is the part holding the glass that slides or swings. On a double-hung, a spring or weight system called the balance holds each sash up at any height.

The seal, often a foam or rubber strip, that closes the gap between a sash and the frame when the window is shut. Worn or missing weatherstripping is a common source of drafts that has nothing to do with the glass.

Two or more separate window units joined together, at the factory or on site, into one combined frame. Lets a picture window flanked by two operable windows, for example, read as a single wide opening.

The main door into the house, and the narrow fixed glass panel or panels often set beside it. Sidelights add light to an entryway and are usually sized and glazed to match the door.

A large, usually glass, door with one panel that slides past a fixed panel to open. Common at a back patio or deck, and prone to its rollers or track wearing out after years of use.

A pair of doors, both usually glazed, hinged on opposite sides so they swing open from the middle. Gives a wider opening than a single door and is common at a patio or as an interior feature.

A second, lighter door mounted outside the main entry door, usually fitted with a glass panel that can be swapped for a screen. Adds a layer of weather protection and airflow without touching the entry door itself.

The threshold is the sill piece a door closes against; the sweep is the strip on the door's bottom edge that seals against it. Both wear down over time and are a common source of drafts and water at a door.

A siding material made from cement, sand, and cellulose fibers, formed into planks or panels. Holds paint well and resists rot, insects, and fire better than plain wood siding.

PVC panels that lock together to cover an exterior wall. Low maintenance and never needs painting, but it can crack under a hard impact and fade over time in direct sun.

A cement-based plaster applied over a wire mesh or board base and finished with a textured coat. Common in drier climates and prone to cracking if water gets trapped behind it.

A thin layer of natural or manufactured stone applied over a wall for the look of solid stone without the structural weight or cost. Usually used as an accent rather than covering a whole house.

Horizontal boards or panels installed so each course overlaps the one below it, shedding water down and out. The most common siding profile, whatever the material underneath, wood, fiber cement, or vinyl.

House wrap is the water-resistant barrier stapled over the sheathing before siding goes on, keeping wind and water out while still letting moisture escape from inside. J-channel is the trim piece that finishes the edge where siding meets a window, door, or corner.

The fascia is the board along the roofline where the gutter usually hangs; the soffit is the underside of that overhang, often vented to let air into the attic. Both take a beating from moisture over the years.

Small dents or fractures left in siding, especially vinyl and fiber cement, by hailstones. It can be easy to miss from the ground and is usually documented alongside roof damage on the same storm claim.

Denver Metro note Denver Metro sees enough hail that this comes up on siding and window inspections after a storm.

Siding, trim, or a window torn loose, cracked, or blown off by high wind. It often shows up alongside roof damage after the same storm, since both are on the exterior taking the same gusts.

Denver Metro note Storm claims in Denver Metro usually run through this, so it helps to know the term before the adjuster shows up.

The request filed with an insurer to pay for storm damage to the home. It starts with documenting what is damaged and ends with the insurer approving, adjusting, or denying the amount owed under the policy.

Denver Metro note Storm claims in Denver Metro usually run through this, so it helps to know the term before the adjuster shows up.

The person the insurance company sends out to inspect the damage and decide what the claim will pay for. A contractor can walk the property together with the adjuster so the same damage gets seen by both.

Denver Metro note Storm claims in Denver Metro usually run through this, so it helps to know the term before the adjuster shows up.