Two-track, two-sash
The standard slider: two sashes on separate tracks, each able to open half the width. Simple, economical and quick to make in volume.
Horizontal sliding window systems
Aluminium Sliding Windows for Residential and Project Supply
An aluminium sliding window has one or more sashes that run sideways on tracks inside an extruded aluminium frame, so it opens without swinging into the room or out over a walkway. It is the most economical opening window for apartments, hotels, schools, kitchens and balconies, and modern thermally broken versions reach respectable energy and weather ratings. Metline supplies sliding window profiles in 6063 and 6060 alloy, thermal-break sections and accessories to window fabricators and project buyers worldwide.
- Alloy
- 6063-T5 / T6, 6060-T66
- Tracks
- Two, three or multi-track
- Wall thickness
- About 1.4 – 2.0 mm
- Finish
- Powder, PVDF, anodised, wood-grain
What is an aluminium sliding window?
A sliding window (often called a slider) is built from an outer frame with parallel tracks, sashes that carry the glass and run on rollers, interlocking meeting stiles where the sashes overlap, and a lock that pulls those stiles together. Because nothing swings, the window takes no floor or balcony space and can be made very wide without the hinge loads that limit casements.
Aluminium is the natural frame material for sliders. 6063 alloy extrudes into the complex, thin-walled sections the system needs (tracks, roller channels, interlocks and glazing pockets) with accurate dimensions and a smooth surface for coating. The frame is stiff enough to carry large glass panes, does not rot, swell or rust, and can be recycled at the end of its life.
The trade-off is sealing. A sliding sash has to move along its seals, so it relies on brush (wool-pile) seals and interlock gaskets rather than the compressed gaskets of a casement or tilt-and-turn window. Standard sliders are therefore a little leakier to air and wind-driven rain. Good design closes most of that gap: deeper frames, multiple seal lines, raised inner sill legs and well-sized drainage paths bring quality sliders close to casement performance in normal exposures.
Types of aluminium sliding windows
Three-track
Three sashes or two sashes plus a screen track. Opens two-thirds of the width, or lets a fly screen sit permanently on its own track.
Single-slide with fixed light
One sash slides over a fixed pane. Useful where only partial ventilation is needed and better air tightness is wanted.
Thermally broken slider
Frame and sash are split into inner and outer aluminium shells joined by polyamide strips, cutting heat flow and condensation risk.
Lift-and-slide window
The sash lifts off its seals to move and drops onto compressed gaskets when closed, giving near-casement air and water tightness on large panes.
Slimline slider
Narrow interlocks of about 20 – 30 mm for maximum glass, using stronger profiles or steel reinforcement in the interlock.
Vertical slider (single or double hung)
Sashes slide up and down, balanced by springs or spiral balances; common in North America and for sash-style elevations.
Sliding with integrated screen
Insect screen on an extra track or as a pleated or roll-up screen built into the frame.
Fixed and sliding combinations
Sliders coupled to fixed lights, transoms or casements to fill large openings with one consistent frame.
Reference specification for aluminium sliding windows
Frame and profile
- Alloy and temper
- 6063-T5 or 6063-T6 to ASTM B221 / EN 755-2; 6060-T66 for European systems; 6005A-T6 for heavy interlocks
- Profile wall thickness
- About 1.4 – 2.0 mm on main load-bearing walls, set by span, wind load and local rules
- Frame depth
- Roughly 50 – 80 mm for non-insulated systems; 80 – 150 mm or more for thermally broken and lift-and-slide systems
- Thermal break
- Glass-fibre reinforced polyamide 6.6 strips, typically 14 – 34 mm wide
- Tracks and rollers
- Stainless steel or reinforced-nylon rollers on extruded tracks; adjustable roller carriages sized to sash weight
- Seals
- Silicone-treated wool pile with fin, EPDM interlock and glazing gaskets
Glazing
- Single glazing
- 5 – 8 mm toughened or laminated glass, for mild climates and internal use
- Double glazing
- For example 5 + 12 air/argon + 5 mm or 6 + 12 + 6 mm insulated units, with low-E coating for energy performance
- Triple glazing
- For cold climates in deep thermally broken or lift-and-slide systems
- Safety and acoustic glass
- Toughened, laminated and acoustic-interlayer laminated glass for low-level glazing and noisy sites
Finish
- Powder coating
- Polyester powder to Qualicoat or AAMA 2603/2604; super-durable powders for strong sun
- PVDF coating
- 70 % PVDF systems to AAMA 2605 for coastal and high-UV exposure
- Anodising
- Clear, champagne, bronze or black to ISO 7599 / Qualanod, 15 – 25 µm by exposure
- Wood-grain
- Sublimation transfer over powder coat for a timber look without timber maintenance
Final dimensions, glass and finish are confirmed against the project drawings, wind-load calculation and test reports.
Performance ratings and how to read them
Performance depends on the whole system, its size and how it is installed, so compare test reports rather than brochure claims. The ranges below indicate what different categories of slider typically achieve when tested to European classification standards.
| Property (test / classification) | Basic non-insulated slider | Quality thermally broken slider | Lift-and-slide |
|---|---|---|---|
| Air permeability (EN 1026 / EN 12207) | Class 1 – 2 | Class 3 – 4 | Class 4 |
| Watertightness (EN 1027 / EN 12208) | Class 2A – 4A | Class 5A – 7A | Class 7A – 9A |
| Wind load resistance (EN 12211 / EN 12210) | Class B2 – B3 | Class B3 – C4 | Class B4 – C5 |
| Thermal transmittance Uw (EN ISO 10077) | About 4.5 – 5.8 W/m²·K (single glass) | About 1.4 – 2.0 W/m²·K | About 1.0 – 1.6 W/m²·K |
| Sound reduction Rw (EN ISO 717-1) | About 25 – 30 dB | About 30 – 36 dB | About 32 – 40 dB |
Indicative ranges only. In North America the same properties are rated to AAMA/WDMA/CSA 101/I.S.2/A440 as a performance class (R, LC, CW or AW) and grade, with U-factor rated by NFRC 100.
If a project sits on an exposed coast, above about ten storeys, or in a cyclone or typhoon region, ask for wind and water ratings that match the calculated design pressure before choosing a slider at all. Where the required watertightness is above class 7A or the wind load is high, a lift-and-slide or a casement window is often the safer choice.
Tracks, rollers, drainage and thermal breaks
Tracks and rollers
Rollers should be rated for the sash weight with a safety margin; double-glazed sashes of 1.2 × 1.5 m already weigh 35 – 40 kg. Stainless steel wheels or bearings last longest. Raised track rails keep the rollers out of dirt and water.
Interlocks
The meeting stiles hook together when closed. Deep interlocks with a gasket and a pull-in lock reduce air leakage and stop the sashes rattling in wind.
Drainage
Water that passes the outer seals is collected in the sill and drained outside through slotted, baffled weep holes. A stepped sill with a higher inner leg stops wind pushing water into the room.
Seals
Wool-pile seals with a central fin seal the sliding joints; EPDM gaskets seal the glass. Seals wear over time and should be replaceable without dismantling the frame.
Thermal break
Polyamide strips separate inner and outer aluminium shells. Wider breaks and foam-filled chambers lower the frame U-value and keep the inner surface above the dew point.
Locks and safety
Hook locks or multi-point locks, child-safety restrictors on upper floors, and anti-lift blocks so a closed sash cannot be lifted off its track from outside.
Sliding or casement window: how to choose
| Factor | Sliding window | Casement / tilt-and-turn window |
|---|---|---|
| Space needed to open | None; the sash stays in the frame plane | Swing space inside or outside |
| Maximum opening area | About half (two-track) or two-thirds (three-track) | Up to the full sash area |
| Air and water tightness | Good to very good with quality seals | Excellent with compression gaskets |
| Wind exposure | Best for low and medium exposure | Suits high-rise and storm-prone sites |
| Insect screens | Easy, on a dedicated track | Possible, more complex for outward sashes |
| Cleaning outer glass | Lift-out sashes or cleaning from outside | Inward-opening sashes clean from inside |
| Cost per m² | Lower | Higher |
| Typical use | Apartments, hotels, schools, kitchens, balconies | High-rise homes, cold climates, energy-led projects |
A practical approach used on many residential projects is to mix both: sliders in kitchens, utility rooms and balcony walls where space is tight and screens are wanted, and casement or tilt-and-turn windows on exposed elevations and bedrooms where air tightness and acoustic comfort matter most. See our aluminium casement windows for the alternative.
Where aluminium sliding windows are used
- Apartments and housing developments: repeated window types delivered by floor and block, often with integrated screens
- Balconies and kitchens: wide openings for light and air where a swinging sash would obstruct
- Hotels, hostels and student housing: durable, easy-to-use windows with restrictors for safety
- Schools and hospitals: sliders with limited opening and robust hardware for frequent use
- Offices and mixed-use buildings: sliders combined with fixed lights in ribbon or punched windows
- Coastal and tropical homes: PVDF or anodised frames with stainless steel rollers and fly screens
- Renovation: replacing old steel or timber sliders with thermally broken aluminium
A typical apartment specification might include two-track sliders of about 1500 × 1200 mm in bedrooms with 5 + 12 + 5 mm low-E glass and a fly-screen track, three-track sliders across the balcony wall, and fixed lights over kitchen counters, all powder coated in one colour, with profiles labelled by unit and floor for the fabricator.
How to order sliding windows: RFQ checklist
A complete enquiry lets us quote accurately the first time. Include as much of the following as you have; we can advise on anything still open.
- Window schedule or elevations with each opening size, quantity and reference
- Track and sash configuration (two-track, three-track, fixed plus slide, lift-and-slide)
- Thermal break required or not, and any target Uw value
- Glass build-up, safety glass zones and acoustic requirements
- Wind load or building height and location, and any required test classes
- Finish type and colour (RAL, anodised shade or wood-grain)
- Insect screens, locks, restrictors and handle colour
- Destination port or site, packing and labelling needs
- ReviewWe check sizes and loads against system limits and suggest the right profile series and glass.
- ApproveShop drawings, section details and finish samples are sent for approval.
- Produce and inspectProfiles are extruded, coated and checked for dimensions and coating thickness before packing.
- Pack and shipProfiles are wrapped, edge-protected and bundled or crated by floor or block, with mill test certificates (EN 10204 3.1) for the aluminium on EXW, FOB, CIF or DAP terms.
References and standards
- EN 14351-1 – Windows and doors: product standard, performance characteristics
- EN 12207, EN 12208 and EN 12210 – Classification of air permeability, watertightness and wind load resistance of windows and doors
- AAMA/WDMA/CSA 101/I.S.2/A440 – North American Fenestration Standard for windows, doors and skylights
- ASTM B221 – Standard Specification for Aluminum and Aluminum-Alloy Extruded Bars, Rods, Wire, Profiles, and Tubes
- EN ISO 10077-1 – Thermal performance of windows, doors and shutters: calculation of thermal transmittance
Aluminium (aluminum) sliding windows: frequently asked questions
Are aluminium sliding windows energy efficient?
Thermally broken sliders with low-E double glazing typically reach Uw values of about 1.4 – 2.0 W/m²·K, which meets many warm and temperate-climate codes. Non-insulated sliders with single glass lose much more heat and are best kept to mild climates or internal partitions. For cold climates, a lift-and-slide or tilt-and-turn window is usually the better choice.
How do I choose between two-track and three-track sliding windows?
Two-track windows open half the width and cost less. Three-track windows open two-thirds of the width, or keep one track for a permanent insect screen. Choose three-track for wide openings, balconies and mosquito-prone regions.
Do sliding windows leak more than casement windows?
Standard sliders allow somewhat more air and water through because their sashes move along brush seals rather than pressing onto gaskets. Quality sliders with interlock gaskets, multiple seal lines and stepped sills perform well in normal exposures. On exposed high-rise elevations, casement or lift-and-slide windows are safer.
Can aluminium sliding windows be made soundproof?
They can be improved considerably with laminated acoustic glass, asymmetric double glazing, tight interlocks and good perimeter sealing, reaching around 35 – 40 dB Rw in better systems. For very noisy sites near airports or rail lines, a dedicated acoustic window is the better option.
Which aluminium alloy is used for sliding window frames?
6063-T5 and 6063-T6 extrusions are standard, with 6060-T66 common in Europe. They extrude into thin, detailed profiles and take powder coating, PVDF and anodising well.
Can I get a quotation without full drawings?
Yes. Opening sizes, quantities, preferred system type and destination are enough for a budget price; final pricing follows once drawings, glass and finish are confirmed.
Need sliding window profiles for a project?
Send your window schedule, glass and finish requirements and destination. We will reply with profile recommendations and a delivered quotation.
