Two sashes, gas struts, one movement: the whole opening clears above the counter and the window seals like a casement when you close. Supplied in aluminium, in sizes and designs to the opening, installed with the storefront.
A fold-up window is a vertical bi-fold: two glazed sashes hinged to each other and to the head of the frame, which fold up and outward on gas struts so the whole opening clears in one movement. Nothing slides sideways, nothing swings into the room, and there is no track on the sill — which is why it is the window for restaurant bars, café counters, kiosks, kitchens and any pass-through where a counter runs under the glass. Alex GC supplies fold-up windows in aluminium, in sizes and designs to the opening, and installs them with the storefront around them.
A black colonial-grid fold-up window on the sample stand: the lower sash lifts, the pair folds against the head and the opening is clear from the counter up.
The frame is a normal aluminium window frame. Inside it sit two sashes, one above the other, joined by a hinge along their meeting rail and hinged again to the head of the frame. Lift the lower sash and it swings up; the meeting hinge lets the two sashes fold flat against each other and the head hinge carries the folded pair up and out, so the assembly ends up stacked horizontally at the top of the opening, outside the plane of the wall, held there by gas struts.
The gas struts do the work. They are sized to the weight of the glazed sashes so that the window lifts with one hand, holds itself at any position, and closes without slamming; a heavier or wider unit takes stronger or more struts, which is why the size and the glass make-up have to be settled before the hardware is chosen. Closed, the sashes lock with a multipoint or a pair of latches at the sill and compress on gaskets like any casement, so the window seals properly when the restaurant is shut.
Some designs fold the other way: the sashes are hinged at the sill and fold down outward to make a shelf, or the pair folds inward. The outward-and-up version is the one that works for a counter, because it leaves the whole depth of the bar free and puts the glass out of the way of heads and trays.
A white two-sash fold-up window in a showroom display beside a matching door: lifted, the sashes fold flat against the head and the counter opening is clear.
Restaurants and bars. A bar counter that runs through the window line is the classic use: the fold-up opens the bar to the sidewalk or the garden in one movement, the counter stays clear, and the window closes and seals when the weather turns. It is the alternative to a horizontal bi-fold, which needs a track on the counter, and to sliders, which never clear more than half the opening.
Cafés, coffee windows, ice-cream and takeout counters. A walk-up service window that opens fully during the day and locks like a window at night; the counter under it can be a shelf on brackets or a full bar top.
Kiosks, ticket booths, concession stands, stadium and park concessions. Anywhere staff serve through an opening and need it weather-tight between shifts.
Kitchens, home bars, pool houses and terraces. A fold-up over a kitchen counter to a deck or a garden bar, or between a pool house and its terrace; the residential versions are the same mechanism in a residential frame.
Interior pass-throughs. Between a kitchen and a dining room, a bar and a lounge, or a serving hatch in a hall or a school, single-glazed and without weather seals.
| Type | How it opens | Clear opening | Sill | Best for |
|---|---|---|---|---|
| Fold-up (vertical bi-fold) | Sashes fold up and out on gas struts | Full width and height | Flat sill, no track | Bar and service counters, pass-throughs |
| Horizontal bi-fold | Panels fold sideways in a track | Nearly full width | Track on the counter or floor | Wide openings without a counter |
| Sliding / stacking | Panels slide behind each other | Half to two-thirds | Track | Long low openings where a track is acceptable |
| Gas-strut awning | Single sash swings out at the bottom | Full, but the sash hangs in the way | Flat sill | Small service windows |
| Roll-up / shutter | Rolls into a box at the head | Full | None | Where glass is not wanted |
Fold-up windows come in a range of sizes: single units from about 3 feet wide and 3 feet tall up to roughly 8 feet wide and 5 feet tall, and wider openings as a run of units side by side between mullions. Above about 6 feet of width the sashes get heavy, and the strut count, the hinge specification and the head structure are engineered to the unit rather than taken from a catalogue; we settle size before we quote the hardware.
Designs run from a plain frame with clear glass to divided-lite grids — the black colonial grid in the sample above suits a brick or a traditional storefront — in any RAL colour, two-tone inside and out, and with matching swing doors and fixed lites so a whole facade reads as one system. Options include an insect screen on the inside, a counter or bar shelf integrated with the sill, laminated or acoustic glass, low-E insulated glass for the energy code, and a lockable limiter that holds the window part-open.
Every fold-up window is glazed with tempered safety glass, since the sashes move and sit within reach; laminated tempered glass where security matters after hours. The frame is thermally broken aluminium on exterior units, so the window meets the same energy requirement as the storefront around it, and a plain non-thermal frame is acceptable for interior pass-throughs.
When the folded sashes project over a public sidewalk they count as a projection from the building line, and the Department of Buildings and the storefront rules on projections apply: the height above the sidewalk and the depth of the projection are what get checked. On a private terrace, a garden or a courtyard there is no projection issue. A fold-up in an existing storefront is usually a like-for-like glazing change; a new or enlarged opening needs a permit, and a restaurant in a landmark district needs LPC sign-off on the storefront change. We handle the filings with the shop drawings.
Two things decide whether the window works day to day: the head has to carry the folded sashes and the strut reaction, so a lintel or a steel header is checked before we fabricate; and the sill has to drain, because a counter that runs under the glass collects rain when the window is open. We detail the sill with a drained threshold and a counter flashing so the bar top stays dry and the wall below it stays sound. See storefront replacement and commercial doors for the rest of the front.
Send us the opening width and height (or a photograph with a tape in it), whether there is a counter and what it is made of, which way the window faces and what is outside it, and the look you want — plain, grid, colour. We come back with a size and design proposal, the glass and hardware named, a price and a lead time; a fold-up window is typically six to ten weeks from approved drawings, and we install it with the storefront, or supply it to your contractor with the installation drawings. We also ship nationwide as part of a container order.
A vertical bi-fold window: two sashes hinged to each other and to the frame head that fold up and outward on gas struts, clearing the full opening with no sill track and nothing swinging into the room.
A fold-up window: the counter stays clear, the opening clears fully in one movement, and the window closes and seals like a casement. Horizontal bi-folds need a track on the counter and sliders clear only half the opening.
Single units from about 3 by 3 feet to roughly 8 by 5 feet, and wider openings as a run of units between mullions; above about 6 feet wide the struts, hinges and header are engineered to the unit.
Yes; closed, the sashes compress on gaskets and lock at the sill with a multipoint or latches, on a thermally broken frame with low-E insulated glass, so they meet the same energy requirement as the storefront.
A like-for-like change in an existing storefront usually is not; a new or enlarged opening needs a DOB permit, sashes that fold out over a public sidewalk are checked as a projection, and landmark districts need LPC sign-off on the storefront change.
Yes, an insect screen on the interior side; it stays in place while the sashes fold out.
Yes; the gas struts hold the sashes at any position, and a lockable limiter fixes it where you want it.
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About this page. Written by Alex GC Inc. d/b/a Alex Glass Construction and reviewed before publication by Aleksandr Chernovolenko, Managing Partner, with our design and estimating lead and a field foreman. Our foremen hold the NYC DOB Site Safety Training supervisor card and our crews the 40-hour worker card; we are certified to fabricate, install and service Alutech and Everest aluminum systems. Facts are drawn from our own projects, manufacturer test data and the applicable codes; where we are giving an opinion, we say so. Last reviewed September 2026. Credentials
Send the opening size and a photo; we come back with a size, a design and a price.
