Every window term, decoded.

A price presented as available only if you sign during the visit — the in-home-sales pressure close.

A glassed-in room with minimal or no insulation, not tied to the home's heating and cooling — comfortable spring, summer, and fall, but not in real heat or cold.

A fully insulated, climate-controlled sunroom built to addition-level standards — insulated glass, insulated walls/roof/floor, tied to heating and cooling — usable year-round.

AL — air leakage

An NFRC rating for how much air slips through the window assembly. Lower means fewer drafts; on the label it's reported as 0.3 or lower.

A metal frame — strong and slim, but the worst insulator of the common materials, because aluminum conducts heat and cold straight through.

Ordinary, slow-cooled “standard” glass — the cheapest kind, and the base most other glass starts as before it's tempered or laminated.

An inert, harmless gas denser than air, sealed between the panes to slow heat transfer. A cheap, standard upgrade over a plain air gap.

The vertical strip where a pair of doors (double or French) meet — the piece one door latches into that seals the gap between them.

A sash hinged at the top that cranks outward, so the open glass forms a little “awning.”

A foam cord pressed into a deep gap around the window before sealant, so the caulk bonds to two sides at the right depth instead of filling a bottomless joint.

The hidden spring mechanism inside a hung window's jambs that counterweights the sash so it stays put wherever you stop it.

Three panels — a flat center parallel to the wall with two angled sides — that project out to make a small alcove.

A vertical siding look — wide boards with narrow strips (battens) covering the seams between them.

Four or more equal panels curving out in a gentle arc — a rounded cousin of the bay.

Where the ends of two siding panels meet in the same course. On vinyl they overlap; on fiber cement they're a caulked or flashed seam.

Tiny breather tubes some makers add to a sealed glass unit shipped to high elevations, to equalize pressure so the panes don't bow or stress the seal.

A single sash hinged on the side that cranks fully open like a door.

A peaked sunroom roof that rises to a ridge, giving a tall vaulted ceiling instead of a single flat slope.

A wood-frame window wrapped on the outside with a weatherproof skin (aluminum, vinyl, or fiberglass), so the interior stays real wood while the exterior shrugs off weather.

The classic horizontal siding look — straight boards, each lapping over the one below. The most common profile.

A frame made from a blend of materials — often wood fiber plus PVC or fiberglass resin — engineered to be stronger and more stable than plain vinyl.

CR — condensation resistance

An NFRC score from 0–100 for how well a window resists interior condensation. Higher resists sweating better.

A traditional glass garden room — mostly glass walls and a glass or polycarbonate roof, often on a low brick base.

One horizontal row of siding. Panels are described by course height — “double 4” is two 4-inch faces per panel, “double 5” two 5-inch faces.

The drying agent packed inside the spacer of a sealed glass unit, there to absorb any trace moisture and keep the gap clear.

DP rating

How much wind load a window is rated to withstand, tested to standards. A higher DP means it holds up to stronger storms.

The flexible seal along the bottom edge of a door that presses against the threshold to block drafts, water, and bugs.

A window whose two sashes both slide up and down and, on most modern units, tilt inward for cleaning. The traditional American window.

Two panes of glass sealed with a gas gap between them — the NC standard for replacement windows.

A small flashing ledge installed above the window that kicks rain running down the wall out and away from the top of the frame.

A siding profile with a notched groove along the top of each course, throwing a stronger shadow line than plain lap siding.

EERO — emergency escape and rescue opening

A window big enough to climb out of in a fire (or for a firefighter to climb in). Bedrooms and finished basements generally require one.

A government efficiency label. A window earns it by meeting U-factor and SHGC thresholds for its climate zone — a quick “efficient enough” screen, though not the strictest tier.

The in-home worksheet a rep fills out to turn your current power bill into a projected monthly “savings” that helps justify the price.

A claim that you're buying straight from the maker with no middleman. Sometimes literally true; often a framing used to justify an in-home-sales premium.

The horizontal board that caps the ends of the roof rafters along the eave — where the gutters mount.

A dense siding board of cement, sand, and cellulose fiber — the premium NC default. Non-combustible, rot- and pest-resistant, and it reads like painted wood.

An entry door with a molded fiberglass skin over an insulated foam core — the premium replacement default.

pultruded fiberglass

A frame made of pultruded glass fibers — stronger and more dimensionally stable than vinyl, holding paint and shape in heat. A genuine step up, priced like one.

Andersen/Renewal by Andersen's proprietary composite frame material — a blend of wood fiber and PVC. A real material, marketed as a category of its own.

The layered, overlapping water barrier wrapped around a window opening that directs rain away from the wall. The difference between a dry wall and a hidden leak.

Haze or moisture trapped between the panes — a sign the sealed glass unit's seal has failed and its insulating gas has leaked out.

The fixed outer perimeter anchored to the wall that holds the sash. Frame = stationary; sash = moving.

A patio (or interior) door of one or two panels that swing open on hinges from the center, meeting at an astragal.

Two ways to replace a window. An insert (pocket) drops a new unit into your sound existing frame. A full-frame tear-out goes back to the rough opening and rebuilds it.

A small glass box that projects outward with a glass top and interior shelves — a mini-greenhouse, usually over the sink.

The narrow strip that holds the glass unit in place against the sash. On modern windows it usually snaps in from the interior.

The decorative bars that give a window a divided-pane look. Sold three ways: sealed inside the glass, stuck on the surface, or as true separate panes.

GBG — grilles between glass

Decorative grille bars sealed inside the insulated glass unit, between the panes.

How a door is “handed” — which side the hinges are on (left or right) and which way it swings (in or out) — described from a set viewpoint so the factory builds it to fit.

Removing and disposing of your old windows and debris after the swap.

A sash hinged at the bottom that tilts open inward from the top.

WRB — weather-resistive barrier

The sheet material wrapped over the wall sheathing, under the siding, that blocks bulk water while letting the wall dry — the last line of defense behind the siding.

International Energy Conservation Code climate zone

The building-code climate map that sets insulation and energy requirements by region. North Carolina spans IECC zones 3A, 4A, and 5A — warm Piedmont and coast to cold mountains.

insulated glass unit

The sealed sandwich of two (or three) panes with a gas-filled gap and a spacer around the edge. The “glass” in a modern window is really this whole unit.

Vinyl siding with rigid foam laminated to the back, adding some insulation and stiffness versus hollow-back panels.

A quote that breaks the job into its parts — window units (type, size, material, glass, energy ratings), labor, trim and sealants, old-window disposal, permits, and both warranties — instead of one lump-sum total.

A J-shaped trim that receives the cut edges of siding around windows, doors, and roof lines and hides them.

A bank of horizontal glass slats that crank open together like a set of blinds.

The vertical sides — and the top “head jamb” — of the window frame that the sash rides against or seals to.

An inert gas denser than argon, sealed between panes where the gap is too narrow for argon to work well — mainly the thin gaps of a triple-pane.

The installer's guarantee on the install itself — leaks, drafts, misalignment from bad sealing — as opposed to the maker's guarantee on the product.

Two panes bonded to a tough plastic interlayer, so the glass holds together when broken. The basis of impact-rated coastal windows and a strong sound blocker.

A warranty term that means three very different things depending on whose lifetime — and the difference is almost never on the price sheet.

The glass area in a door — and the shorthand for how much there is: “half-lite” (glass on the top half), “full-lite” (mostly glass), “quarter-lite,” and so on.

low-emissivity coating

A microscopically thin metallic layer baked onto window glass that lets daylight through but reflects heat. It's the single biggest driver of how a window performs.

A window-and-door-rated spray foam used to insulate the gap around the frame — deliberately low-expanding so it fills without pushing.

MSRP, in a window pitch

A high “list” number a window is almost never actually sold at — the starting point a big discount is measured down from.

The horizontal bar where the two sashes of a double- or single-hung window meet and lock in the middle.

Selling the job by its monthly payment instead of its total price.

Two or more units — a door with its sidelites, or windows joined side by side — factory-joined into one assembly. “Mulling” is the joining.

The structural post between two separate window units joined side by side.

A vinyl (or composite) frame built with several internal hollow chambers — and sometimes filled with foam — so the frame itself insulates better.

A locking system that throws bolts at several points along the door edge with one lift-and-turn of the handle, instead of a single deadbolt.

The thin bars that divide a window's glass into smaller panes — or that look like they do. In old windows they held separate small panes; today they're usually decorative grilles.

A thin flange around a new-construction window that nails flat to the wall sheathing so the unit can be flashed into the wall.

A window with a nailing fin, meant to be installed with the exterior cladding open so it can be fully flashed into the wall — as on a new build or a full tear-out.

National Fenestration Rating Council label

The standardized white sticker on a new window listing its independently-tested U-factor, SHGC, and more — so you can compare any two windows on the same terms.

Glass that's textured, frosted, or patterned to blur the view while still letting light through.

A catch-all for enclosing an existing patio or porch with screen, vinyl, or glass panels — anywhere from a screen room to a near-sunroom.

A quote's total divided by its window count — the only number that compares apples-to-apples across bids.

Local government authorization to do the work, with an inspection to confirm it meets code. Replacing like-for-like windows often doesn't need one; resizing openings, egress work, structural door changes, and sunrooms usually do.

A fixed pane with no operable sash — glass sealed straight to the frame.

A complete door unit — slab already hung on hinges inside a new frame, with the sill and weatherstrip — that installs as one piece.

Starting with a deliberately high “list” or “retail” number so every discount from it feels like a win — the setup behind “$60,000, but today $34,000.”

The window maker's guarantee against defects in the frame, sash, hardware, and glass seal — separate from the installer's labor warranty.

Coverage that shrinks over time — as the product ages, the maker pays a smaller share of a claim and you pay the rest.

The horizontal top and bottom members of a sash. The bottom rail is the one you push; the “meeting rail” is where two sashes overlap.

The exposed face height of each siding course — how much of one board you see before the next laps over it.

The bare framed hole in the wall — studs and header, no window — that a window is built to fit into, slightly larger than the unit so it can be shimmed and sealed.

A financing offer — “no interest if paid in full by month 12 or 18” — where interest is only waived if you clear the whole balance by the deadline. Miss it, and interest is charged back on the entire original amount.

The moving framed panel that holds the glass — the part that slides, tilts, or cranks. The frame stays put; the sash is what operates.

An enclosure of mesh screen panels under a solid roof — bug-free open air, with no glass and no insulation.

solar heat gain coefficient

How much of the sun's heat the window lets in, 0–1. Lower blocks more heat. In cooling-dominated North Carolina, this is the number you feel.

Thin tapered wedges the installer slips behind the frame to set the window plumb, level, and square before fastening it.

A tall narrow glass panel beside an entry door — on one or both sides — that lets light into the entry.

The bottom horizontal member of the window frame — the “floor” of the opening that sheds water outward.

A waterproof tray set under the window at the bottom of the opening that catches any water getting past the window and drains it back outside.

Only the bottom sash moves; the top sash is fixed. The budget cousin of the double-hung.

The door panel by itself — just the swinging part, no frame, hinges, or hardware.

A window whose sash or sashes glide left-and-right on a horizontal track — no cranks, no springs.

A patio door with panels that glide horizontally on a track — one fixed, one sliding.

The weight of accumulated snow a roof must be engineered to carry, set by local code for the area.

The underside panel of a roof overhang or porch ceiling, usually vented to let the attic breathe.

The two ways a Low-E coating is applied. Soft-coat (sputtered) performs better but is delicate, so it must live sealed inside the glass unit; hard-coat (pyrolytic) is tougher and can be exposed, but blocks less heat.

An all-glass sunroom — glass walls AND a glass roof, with minimal framing — for maximum light and views.

The first strip nailed along the bottom of a wall that the first course of siding locks into.

An entry door with a steel skin over a foam core — the budget-strong option.

The vertical side members of a sash (as opposed to the horizontal rails) — the upright edges of the moving panel.

A secondary outer door — usually glass over screen — mounted in front of your entry door for weather protection, light, and ventilation.

A sunroom roof that's a single flat slope pitching away from the house — the simpler, lower-cost roof style.

Glass heat-treated to be roughly 4–5× stronger than ordinary glass; when it does break it crumbles into small blunt pebbles instead of sharp shards.

A closing routine where the rep steps away to “call the manager” and returns with a further, seemingly special discount to prompt a signature.

A non-conductive barrier built into a metal frame to interrupt the path heat and cold would otherwise take straight through the metal.

The bottom sill piece you step over in a doorway, which the door's sweep seals down against to keep out water and air.

A European-style window whose single handle does two things — tilt the top in for a crack of air, or swing the whole sash in like a door.

Glass colored in the mass (gray, bronze, green, blue) to cut glare and some solar heat.

A warranty that survives a home sale, passing to the next owner instead of ending when you move.

A window above a door (or another window) — sometimes a decorative arch, sometimes an operable vent.

Three panes with two gas-filled gaps, instead of the standard two panes and one gap.

How well a whole window keeps heat in — the rate it loses heat. Lower is better; most quality NC windows land around 0.25–0.30.

UI — width plus height

A window's width plus its height in inches. Price books are banded by UI, so crossing a band bumps the same window into the next price bracket.

polyvinyl chloride

The most common replacement-window frame material — rigid PVC plastic. The NC value default, and itself split into tiers (recycled-content vs first-generation).

Extruded PVC panels that “float” on the wall — the budget-friendly, no-paint default siding.

visible transmittance

How much visible light the window lets through, 0–1. Higher means a brighter room. Separate from how much heat it blocks.

The strip around the edge of the sealed glass unit that holds the panes apart. “Warm-edge” means it's made of a low-conducting material instead of plain aluminum.

Small drainage slots along the bottom outside edge of a window that let rainwater escape instead of pooling in the frame.

Coastal areas with high design wind speeds — in NC, roughly 130 mph and up — where code requires glazed openings to resist flying debris, either with impact-rated (laminated) glass or approved shutters.

A traditional solid-wood frame — an excellent natural insulator with unmatched historic looks, but the highest-maintenance material.