Utilise the natural strength of aluminium to create slim thermally broken profiles
• Low maintenance hard wearing powder
coated aluminium
• 20mm sight lines
• Multi point locking system
• U values from 1.3W/M2k
• Moving corner posts
• 4-6 week lead times
• Automated option
• Flush tracks and slot drainage available
• Available as sliding windows
• A variety of glazing options including solar control and easy clean
• Up to 4 track available giving you 80% opening
Our vision is simple. Being able to see exactly what you want: your view, not your window or door.
We specialise in installing frameless sliding doors and windows in homes and commercial buildings across the UK. Taking glazing to a whole new level, by making it invisible, we are committed to product development of our systems to ensure we are always at the forefront of glazing technologies.
Specification Data
| Applications | All general light applications |
| Features | Frameless sliding doors incorporates frameless design with 20mm sightlines allowing for as much daylight as possible. Recessed tracks allow for as little interrupted views as possible. Highly efficient double glazed units with thermally broken aluminium allow for low U values. |
| Colour | Aluminium able to be painted to any RAL, Syntha Pulvin and BS colours. |
| Performance | While all calculations such as wind-loading, U-values, size and weight limitations are calculated on a project basis these are the average values for an average casement. |
| U Values | 1.3W/m2 K (Using a 1.1W/m2 K glass unit) |
| 1.1W/m2 K (Using a 0.7W/m2 K glass unit) | |
| Wind Resistance | EN 12210:2000 Class C5 |
| Water Tightness | EN 12208:2000 Class 7A |
| Air Permability | EN 12207:2000 Class 4 |
| Document Q | Compliant |
| Document L | Compliant |
| Dimensions | |
| Maximum Dimension | Each panel can go 3000mm high by 3000mm, please enquire if you would like to go outside these sizes. |
| Maximum Weights | 500kg – enquire if you would like to go outside this weight. |
| Frame Depth | 44mm |
| Glazing Thickness | 28-32mm double glazed units – triple glazing available on request. |
Make glass the hero of your home. GSL COR delivers a near-frameless look with 20 mm sightlines, thermally broken aluminium and beautifully resolved details like flush tracks and slot drainage. It pairs naturally with our glass extensions, glass links and glass roofs to create bright, seamless spaces that open effortlessly to the garden.
Whether you’re upgrading a period townhouse or finishing a contemporary extension, COR is tailored to your architecture and lifestyle. We coordinate low-profile thresholds, crisp junctions and discreet hardware so the doors look as considered closed as they do fully open. Prefer one design language across elevations? Specify COR as a sliding window in kitchens or utility spaces to match your main sliders.
Popular residential options
Thermally broken frames, insulated glass units and high-quality seals help stabilise indoor temperatures while maximising light. Weather performance is engineered for UK conditions, with reliable resistance to wind, water and air ingress. For sunny aspects, we’ll specify solar-control coatings; for urban plots, acoustic laminates help calm outside noise. Energy and security requirements can be met to UK standards when specified.
What you can expect
Exact limits depend on site conditions, glass specification and structural design—our team will validate spans during survey and CAD.
We keep your programme predictable with an end-to-end service: survey → CAD → manufacture → install → aftercare. We’ll coordinate thresholds, drainage and any electrics for automation, working with your builder to protect finishes and minimise disruption.
Typical timings
Bespoke residential sets commonly start from 4–6 weeks after design sign-off, varying with configuration, glazing complexity and colour finish.
Yes. Flush tracks with slot drainage maintain clean lines and smooth transitions for accessible, family-friendly living.
We can engineer openable glass corners so two sliding screens meet without a fixed post—perfect for terraces and garden rooms.
GSL COR focuses on a near-frameless look with integrated drainage details and typical panel sizes around 3×3 m. GSL 20 is our large-span, high-spec slider with different performance options; compare based on required span, security spec and aesthetic.
