A search for ALPES aluminum system doors sliding type usually hides one real question: is this a sliding door that behaves like a door, or a sliding window that was simply made taller? The difference is not marketing. It is engineering. A system door is a coordinated set of parts - frame, moving and fixed sashes, track, upper guide, rollers, interlock, perimeter seals, glass, locks, and a drainage path - designed to move together for the whole service life of the opening. This article explains what that coordination buys you, maps the four ALPES sliding door families, and gives a framework for choosing among them.
A door leaf carries far more glass weight than a window sash and is operated far more often. If a maker only scales up a window profile, the sash can flex under its own glass, rollers wear early, and the frame can settle out of square. A genuine door system is dimensioned for the door load path from the first extrusion. At ALPES the sliding door profiles are 6060-T66 aluminum at 1.8 to 2.5 mm wall thickness with a PA66GF25 multi-chamber thermal break - the same structural grade used across the window range, but with heavier main load-bearing profiles on the larger doors (the SL155 main profile starts at 2.2 mm).
What you are really buying is the list below working as one unit. If any single item is weak, the whole door feels it within a few years:
ALPES offers four sliding door families. They share the same aluminum grade, thermal-break philosophy, and hardware partners, but they are aimed at different opening sizes, climates, and sightline targets.
| Family | Track and frame depth | Profile wall | Max single sash | Load rating | Signature feature |
|---|---|---|---|---|---|
| SL155 thermal-break sliding door | Four-track, 155 mm | 2.2 to 2.5 mm | 2800 mm wide by 2600 mm high, about 7.5 sq m daylight | 400 kg, 20-wheel self-balancing | Passive check-valve drainage, dual-matrix eight-layer seal |
| SL112 and SL167 heavy-duty | Single or two-track 112 mm, three-track 167 mm | 1.8 to 2.5 mm | Up to 220 kg sash drive | 220 kg sash | 45 mm high-ｄｒｏｐ bottom track, 24A inert-gas glazing |
| SL126 and SL182 (96) | Two-track 126 mm, three-track 182 mm | 2.0 mm, up to 3.0 mm at critical zones | 2500 mm wide by 3000 mm high, about 7 sq m daylight | Door-grade, locally reinforced | Patented eave-style waterproof, continuous four-side seal |
| SL126 and SL182 (75) | Two-track 126 mm, three-track 182 mm | 2.0 mm | Slim 75 mm interlock | Sliding and lift-sliding | 38 mm extreme slim frame, 27A inert-gas glazing, butyl gasket |
Frame depth is a property of the series, not of how many tracks it has. Note that the four-track SL155 is 155 mm deep while the three-track SL182 is 182 mm deep - more tracks does not mean a deeper wall.
Every ALPES sliding door starts from 6060-T66 aluminum. The PA66GF25 multi-chamber thermal break cuts the conductive path through the frame so the interior face stays closer to room temperature. Where a door meets a very hot or very cold climate, the break and the glazing together decide how much energy moves through the opening.
The single most important number on a sliding door is the roller load rating, and it is rated per sash, not per door. Glass is heavy - roughly 2.5 kg for every millimetre of thickness - so a large insulated unit can push a single sash well past 200 kg. The SL155 uses a 20-wheel self-balancing system rated for 400 kg, and the SL112 and SL167 drive sashes up to 220 kg. Specifying the roller to the finished glass weight, not to a catalogue average, is what keeps the door smooth at year ten instead of year two.
A sliding door seals by compression at the interlock and around the perimeter, not by a swinging leaf pressing into a frame. The upper families carry eight-layer or continuous four-side sealing, and the SL155 adds a passive check-valve drain that speeds water out and stops it flowing back. A track that holds water is doing exactly what it was designed to do until the water crosses the interior sill - which is why the drainage path, not the glass, is the part to inspect first if a door ever weeps.
Security on a sliding door comes from multi-point locks that anchor the moving panel top and bottom, plus anti-lift blocks that stop the panel being levered off its track. The locking points are a clamping system as much as a security system: even pressure around the perimeter is what keeps the seals working, so a well-locked door is also a better-sealing door.
The threshold is where the door meets the floor, and it decides both water protection and step-free access. ALPES offers low 8 mm tracks for clear floor lines, 43 mm high tracks and 45 mm high-ｄｒｏｐ bottoms for exposed elevations, and an optional 85 mm water barrier. These are not interchangeable - a barrier that stops storm surge also stops a wheelchair, so the choice has to be made against the actual exposure and the accessibility requirement, not against a photo.
| If your priority is | Start with | Why |
|---|---|---|
| A very large single panel and the heaviest glass | SL155 | Highest load rating and the deepest four-track system for panoramic runs |
| A wide opening split across three tracks on a tight budget | SL112 or SL167 | Flexible fixed and moving layouts with a high-ｄｒｏｐ drain for ground floors |
| Maximum exposed-elevation weather resistance | SL126 or SL182 (96) | Patented eave waterproof and continuous seal, reinforced at critical zones |
| The slimmest visible interlock and cleanest sightline | SL126 or SL182 (75) | 75 mm interlock and 38 mm extreme slim frame for unbroken views |
No published whole-door thermal value is listed for the sliding families, and that is the honest position: a sliding door seals by compression at an interlock, which is a different geometry from an opening casement, so its tested value is not the same number. The lowest published frame-side baseline in the ALPES range is the AW90 tilt-and-turn at K equals 1.3, but that is a different opening type. For a sliding door, ask ALPES for the project-specific Uw calculated against your exact glass build-up and opening size - do not carry a number from another product line into your spec.
ALPES builds from a 100,000 square metre manufacturing base across Foshan and Zhaoqing in Guangdong, and ships in full containers for overseas projects. Buying direct from the sliding door supplier means the same engineering drawings that define the system travel with the order, and a single sash can be re-made to the original specification years later rather than replacing the whole run. For a metal sliding door or an alum sliding door built to a project, that traceability is part of the system too.
| Tell ALPES | Why it changes the door |
|---|---|
| Opening width and height in millimetres | Decides the family, the track count, and the maximum sash |
| Track configuration and panel layout | Sets how much of the opening actually clears when open |
| Glass build-up and any solar or acoustic requirement | Drives the sash weight and therefore the roller rating |
| Climate exposure: coastal, hot, or wind-driven rain | Selects the threshold, the seal strategy, and the finish |
| Threshold type and accessibility need | Balances water protection against step-free access |
| Hardware brand and colour, plus destination port | Locks in the ROTO, Winkhaus, CMECH, or Wehag option and the shipping plan |
Send those six lines and the ALPES engineering team can return a drawing and a bill of materials for the right system rather than a generic price for the wrong one.
