Glossary

The vocabulary on a Florida window quote

Name: Deltona Window Co
Telephone: +13867425619
Price range: $$

34 terms that turn up on labels, on quotes and in the guides on this site, defined for how they apply to a block-walled house in a cooling climate.

Anodized finish: The electrochemical surface treatment on the original aluminum windows in most older Deltona houses, usually silver or bronze. It is thin, it chalks and dulls under decades of ultraviolet, and once it has gone the aluminum underneath starts to pit. A frame that leaves a gray smear on a wet cloth has lost its finish, which is a cosmetic problem rather than a structural one.
Argon fill: An inert gas sealed into the cavity of an insulated glass unit in place of air. Argon conducts heat more slowly than air, so it lowers the U-factor a little. In a cooling climate it is a marginal gain compared with what the coating on the glass does, which is why it belongs low on the list of things worth paying extra for here.
Balance: The spring or coil mechanism inside the jamb of a single-hung or double-hung window that counterweights the sash so it stays where you put it. Balances are a wear part and a replaceable one. A sash that slams shut or will not stay up has a failed balance, not a failed window.
Buck: The wood or precast frame set into a masonry opening that the window fastens to. In Florida block construction the buck can be poured into the wall or attached to it, and how the window is anchored through the buck into the block is part of what the design pressure rating assumes.
Design pressure (DP): The wind load, in pounds per square foot, that a window assembly is rated to withstand, positive pressure pushing inward and negative pressure pulling outward. It follows every Florida window and is calculated for the position the opening occupies on the building. It rates the frame, anchors, glass and hardware as one system.
Fenestration: The trade word for the glazed openings in a building, windows, skylights and glazed doors taken together. It turns up on performance documents and specifications because the numbers are often written against the whole set of openings rather than window by window.
FL number: The Florida product approval number carried by a window sold for use in this state. It identifies the exact assembly and the conditions it was tested under: the sizes it covers, the design pressures it holds, whether it is impact rated, and the installation method behind those figures. Worth asking for and worth keeping.
Flange (nailing fin): The thin projecting lip around a window frame that gets fastened to the sheathing in wood-frame construction and integrated with the flashing. It is the standard detail in stick-built houses and largely irrelevant in Deltona, where most windows anchor into block through the frame instead.
Glazing bead: The removable strip that holds a pane in its sash. Its position matters more than it sounds: interior beading means the glass can only be removed from inside, which is a security consideration on ground-floor openings and a serviceability one when a unit needs replacing.
Horizontal roller: The manufacturer term for what everyone else calls a slider: a window with one or more sashes running side to side on a bottom track. Common in Deltona because the house plans that built the city favored wide openings, and prone to a specific failure where a blocked track ponds water instead of draining it.
Impact rating: Certification that a glazed assembly passed a large missile impact test followed by thousands of pressure cycles on the damaged unit, meaning the opening stays sealed after a strike. Standard practice along the coast, and available everywhere else for anyone who wants it.
Insulated glass unit (IGU): Two or more panes separated by a spacer and sealed at the perimeter, with the cavity between them filled with air or an inert gas. The whole point is the sealed cavity, which is why a failed perimeter seal ends the unit even though the glass itself is undamaged.
Laminated glass: Two sheets of glass permanently bonded to a tough plastic interlayer. When it breaks the fragments stay stuck to the interlayer instead of leaving the opening. It is the basis of impact glazing, and it also cuts sound transmission and blocks almost all ultraviolet light.
Large missile test: The impact test behind hurricane ratings for openings within thirty feet of grade: a timber projectile is fired at the glazing at a specified speed, and the assembly then has to survive repeated wind pressure cycling without opening up. Smaller openings higher up are tested with a small missile instead.
Low-emissivity (low-E) coating: A microscopically thin metallic layer on a glass surface that reflects long-wave heat. Which surface it sits on changes what it does: a coating positioned for a cooling climate rejects solar heat before it enters, while the same technology positioned for a heating climate holds indoor heat in.
Meeting rail: The horizontal member where the upper and lower sashes of a hung window come together, and where the lock engages. A meeting rail that no longer lines up is usually telling you the frame has moved or the sash has dropped, not that the lock is broken.
Miami-Dade NOA: A Notice of Acceptance issued by Miami-Dade County product control. South Florida ran its own stringent product control system long before the state one existed and it still does, so an NOA on a quote does the same job as an FL number and is not a red flag.
Mullion: The vertical structural member joining two window units into one assembly in a single opening. Mullions carry load, which is why a wide multi-unit assembly has its own rating rather than inheriting the rating of the individual windows in it.
Muntin and grid: The bars dividing a pane into smaller lights. True muntins hold separate panes; modern grids sit between the panes or clip to the surface and are decorative. In neighborhoods with covenants, grid pattern is one of the exterior details most often specified.
NFRC label: The performance sticker on a new window from the National Fenestration Rating Council, carrying U-factor, solar heat gain coefficient, visible transmittance and sometimes air leakage. It is the only apples-to-apples comparison between products, and it is on the glass when the window is delivered.
Return: The finished surface running from the face of the interior wall back to the window frame. In block construction the return is plaster or drywall over masonry, and it takes damage when the old frame comes out. Whether the crew patches it back to a paintable finish should be stated on the quote.
Sash: The moving frame that holds the glass, as distinct from the fixed frame it moves within. Most window complaints are sash complaints: the sash sticks, the sash has dropped, the sash will not lock. Some are fixable in place and some end the window.
Seal failure: The end of an insulated glass unit, when the perimeter seal lets moist air into the sealed cavity and the interior surfaces fog or stain. Nothing can be cleaned because both reachable surfaces are already clean. Failures cluster across a house because all the units were manufactured in the same batch.
Single-hung: A window with a fixed upper sash and a lower sash that slides vertically. The dominant window type in Florida housing and in Deltona specifically, because fewer moving parts survive humid air better and a hung sash seals well against wind pressure.
Solar heat gain coefficient (SHGC): The fraction, from 0 to 1, of solar energy striking a window that ends up as heat inside the room, counting both what passes straight through and what the glass absorbs and re-radiates inward. In a cooling-dominated climate it is the single most consequential number on the label.
Spacer: The perimeter component holding the panes of an insulated unit apart and carrying the desiccant that keeps the cavity dry. Warm-edge spacers use lower-conducting materials than the traditional aluminum ones, which reduces condensation at the edge of the glass in humid conditions.
Stucco return: The stucco carried from the face of the wall into the window opening. It is part of the weather barrier on a block house, and cutting an old frame out of it inevitably disturbs it, which is why making it good and tooling the sealant joint properly is a real part of the installation rather than tidying up.
Tempered glass: Glass heat-treated so it is several times stronger than ordinary annealed glass and crumbles into blunt pieces instead of shards. Standard in the places a person could fall against it: beside doors, in bathrooms and low to the floor. Strong, but not the same thing as impact rated, because it does not stay in the opening.
Thermal break: A non-conducting barrier built into the middle of an aluminum frame so the outside face and the inside face are no longer one continuous piece of metal. It is what stops a frame running with condensation on a humid morning, and it is why a modern aluminum window behaves nothing like the original it replaces.
Tilt-in sash: A sash hinged so it swings inward out of its track, letting the outside of the glass be cleaned from indoors. Standard on current single-hung units and absent from the originals in most Deltona houses, which is why people who have never had it rate it higher than they expected to.
U-factor: How fast heat conducts through a whole window assembly, in BTU per hour per square foot per degree. Lower is better insulated. It is the headline number in cold climates and the secondary one here, where the sun coming through the glass outweighs conduction through it for most of the year.
Visible transmittance (VT): The share of visible light that passes through the glazing, from 0 to 1. It matters because aggressive solar-control glass can darken a room, and the useful trade is finding a package that rejects heat while keeping VT high enough that the room still reads as daylit.
Weep hole: The small drainage opening in the bottom of a window frame or sill track that lets water that gets in find its way back out. Blocked weeps are the single most common cause of a window that leaks indoors, and clearing them is close to the whole of window maintenance.
Wind mitigation credit: The reduction a Florida carrier applies to a premium for construction features that reduce hurricane damage, opening protection among them. It rests on documentation of what is physically installed, and it generally rests on every glazed opening being protected rather than most of them.

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