Professional specifications, installation guide & design solutions
Casement windows open outward with a hinge on the side. Modern, efficient design with excellent weather protection. Perfect for residential and commercial applications, sliding-window windows combine functionality with aesthetic appeal. Professional installation ensures optimal performance and longevity.
We carry multiple premium manufacturers for sliding-window windows including:
Each brand offers distinct advantages in performance, design, and price point. We can help you choose the perfect fit for your project.
Proper installation is critical for optimal performance. Our licensed contractors provide:
Installation includes sealing and flashing the perimeter of the opening, because a window is only as watertight as the junction between it and the building. Where an opening needs more than that — a failed sill, damaged masonry, a detail that was wrong to begin with — see waterproofing.
Sliders deserve their own note here, because the sill is doing two jobs at once. It carries the sash on its rollers, and it is the drainage channel that takes water back out of the frame through weep holes.
That makes installation level and drainage critical in a way it is not for a casement. A sill set out of level, or weeps blocked by mortar, sealant or paint during installation, leaves water standing in the track. In winter it freezes there. Most of the sliding window failures we are called to are drainage problems rather than product problems.
Our installation includes a sill pan or end dams where the detail requires it, head and jamb flashing lapped correctly so water is shed outward, and perimeter sealing that does not obstruct the weeps. The materials we use are covered on the waterproofing page.
A horizontal slider is the simplest operating window there is: one or more sashes running on a track in the frame, with nothing projecting into the room or out over the pavement. That simplicity is its real advantage, and it also explains the trade-off that follows.
Panel count is the decision that sets everything else — how much opens, how much glass you get, and what the sash weighs. The trade writes it with X for an operating panel and O for a fixed lite, read left to right from outside.
Two panels. The standard slider. XO or OX has one operating panel and one fixed, with the handing deciding which side opens — specify it against the room, because a slider that opens away from where you stand is a daily irritation. XX has both panels operating on separate tracks, which is useful where the opening has to be reachable from either side. Both give about half the width as clear opening.
Three panels. XOX is the common wide-opening arrangement: a wide fixed centre with two operating end panels sliding inward behind it. It looks like it should open more than a two-panel unit, but the two quarter-width openings still add up to about half. XXO and OXX stack both operating panels to one side, giving a single larger opening at one end rather than two smaller ones — often the better choice where the opening serves a specific route or a table.
Four panels. XXXX or XOOX for genuinely wide openings. Worth knowing that more panels means more meeting stiles, and every meeting stile is a vertical bar of frame in your view and another line to seal. Four panels across a wide opening can read busier than two large ones.
The practical limit is weight. A single panel carrying an insulating unit gets heavy quickly, and beyond a certain size it stops sliding pleasantly no matter how good the rollers are. Where an opening is wide enough to be a problem, we will say whether it should be more panels, a lift-and-slide system or a different window type altogether.
Screens on a slider sit on their own track outside the operating panel, so they cover the opening half rather than the whole window. That is worth knowing before ordering: on an XO unit you get one screen covering one half, not a full-width screen.
Standard fibreglass mesh is the default — typically 18 by 16 weave, flexible, inexpensive, and adequate for mosquitoes and ordinary flies.
Fine mesh, often sold as no-see-um screen, uses a tighter weave around 20 by 20 to stop the smaller biting midges and gnats that pass straight through standard mesh. This is the one to ask for near water — the marsh edges of Jamaica Bay, the Rockaways, the Shore. The trade-off is real: a tighter weave reduces airflow and cuts visibility slightly.
Aluminium mesh holds its shape better than fibreglass and resists sagging on wide panels, but it creases permanently if it is pushed.
Pet-resistant mesh is a heavier woven polyester, worth it on a ground-floor opening where a cat or dog will lean on it. It is noticeably more visible than standard mesh.
Solar screen uses a dense weave to block a substantial share of solar heat before it reaches the glass. It genuinely works on a west-facing elevation, and it genuinely darkens the view — a decision to make room by room rather than across a whole building.
Retractable screens roll away into a cassette when not in use, which suits an opening where the view matters most of the year. They cost more and there is a mechanism to maintain.
Screen frames should be aluminium rather than plastic on anything exposed, and the spline should be replaceable — a re-screen is a cheap repair when the frame is sound and a new unit when it is not.
Most sliders are bottom-rolling: the sash sits on tandem rollers running in the sill track. Roller quality is the single biggest determinant of whether the window still operates well in ten years. Nylon-tyred tandem rollers with steel or brass housings outlast plain plastic wheels by a wide margin, and the difference in unit cost is small.
The sill track is also a drainage channel with weep holes taking water out through the frame. Those weeps are the most neglected part of any slider. Blocked with dirt or paint, water stands in the track, works into the frame and freezes there in winter. Clearing them takes a minute a year and prevents most of the failures we get called to.
Debris in the track is the other common fault. Grit acts as an abrasive under the rollers, and a slider that has become stiff is usually telling you the track needs cleaning rather than the window needs replacing.
This is where a slider gives ground, and it is worth stating plainly because it is the reason to choose a different window in some situations.
A casement or an awning window closes by compression — the sash is pulled tight against a gasket, and the tighter it is drawn the better it seals. A slider cannot work that way, because the sash has to keep moving past the frame. It seals with pile weatherstripping and interlock fins that brush rather than compress. Brush seals are inherently leakier than compression seals, and they wear with use in a way compression gaskets do not.
In practice that means a good slider will usually show higher air infiltration than a good casement of the same size and quality. Modern units with well-designed interlocks and multiple pile lines perform far better than older ones, and for many buildings the difference does not matter. But if the single priority is minimum air leakage, a slider is not the window to reach for, and we would rather say that than sell you one.
New York City sets minimum light and ventilation standards for habitable rooms, and the ventilation half of that test is calculated on the area that actually opens — not the size of the window.
Under NYC Administrative Code §27-2058, for living rooms in multiple dwellings erected after 18 April 1929, the total window area in a room must be at least one tenth of the floor area, every required window must be at least twelve square feet, and at least one half of every required window must open. For one- and two-family dwellings, §27-2062 requires at least forty-five percent of the required window area to be openable.
Now put that beside the geometry above. A slider opens to about half its width — and once you subtract the interlock stile and the frame, the genuinely clear openable area can land slightly under half. On a window that is comfortably larger than the minimum this is academic. On a room where the existing window is already close to the threshold, replacing a double-hung with a slider of the same overall size can move the room from compliant to non-compliant without anything looking different.
This is a real problem on alteration filings and it is entirely avoidable. We check openable area against room floor area at survey rather than after the units arrive. Where the numbers are tight, the answer is usually a casement, an awning or a larger opening — and it is much cheaper to know that before ordering.
Sliding windows are a post-war product, so the neighbourhoods where they dominate are the neighbourhoods that were built or re-glazed after about 1950. These describe the building stock rather than any specific client project.
Ranch houses, split-levels and attached homes from the 1960s and 70s, much of it originally glazed with aluminium sliders. This is the most common slider replacement work we do, and it is usually straightforward: the openings are wide rather than tall, which suits the format, and there is normally enough window area that the ventilation calculation is not tight.
The recurring finding is that the original frames are non-thermally-broken aluminium, which condenses heavily in winter. People often assume the condensation means a failed seal when it is the frame conducting cold straight through. Replacing like for like in a modern thermally broken frame solves it.
Post-war garden apartments and detached housing, with a lot of original wide openings. Garden apartment work brings the co-op question: many buildings require the replacement to match across the elevation, so the configuration and the frame colour are decided by the board rather than the individual owner. Establishing that before quoting saves a conversation later.
High-rise residential from the late 1960s and 70s, where sliders were the standard fit. Two things follow. Height means wind pressure, so the interlock and weatherstrip specification matters more than it would at grade — a slider that performs adequately on a second floor can whistle on a twentieth. And access is by stair or service lift with the building's rules attached, so scheduling is part of the job rather than an afterthought.
Attached and semi-detached post-war housing, much of it low-lying and close to Jamaica Bay. The slider format suits the stock, but the coastal proximity changes the hardware specification: rollers and fasteners in a salt-air environment want stainless rather than plated steel, and the sill drainage matters more where wind-driven rain arrives off the water.
Sliders come into their own where nothing can project — a window over a side alley, next to a walkway, or in a below-grade opening where a casement would foul the areaway. Where a below-grade room is habitable, the light and ventilation rules above still apply and are usually the binding constraint, so that calculation comes first.
Tell us the opening size, whether the room is a habitable room, and whether the building is a multiple dwelling or a one- or two-family house. We will check the ventilation numbers before quoting and tell you if a slider will not satisfy them. We supply and install across Manhattan, Brooklyn, Queens, the Bronx and Staten Island, and throughout Northern New Jersey, the Jersey Shore, Philadelphia and the Lehigh Valley.
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