Sheerline Classic Windows
Steel-look aluminium windows in four profiles, made in Keighley
Classic Steel-Look Windows
Sheerline Classic Heritage Windows
Sheerline Classic windows are steel-look aluminium windows with sightlines from 35.5mm and made to measure in our own factory in Keighley.
They give you the layered look of early twentieth-century steel glazing at a fraction of the cost of the real thing and meet current building regulations.
Typical 4-week lead time for supply only
Made to measure
10-year manufacturer warranty
Nationwide supply & delivery
Regional survey & installation
25-year paint finish guarantee
PAS24 Secured by Design accredited
Made in Keighley, delivered UK-wide
Request a Bespoke Quote →
Or call our team on 01535 603909
What are Sheerline Classic windows?
Sheerline Classic is the heritage window system made by Sheerline, part of Garnalex and we fabricate it here in Keighley. The frames come in four profiles – Contemporary, Contemporary Flush, Stepped and Stepped Flush – and it is the stepped option that gives you the shadow line of steel glazing rather than the flat square edged profile of a modern window system.
Within the Sheerline aluminium frame, Thermlock® multi-chamber technology does the thermal work. Each window is carefully hand-tuned as it is assembled by using a patented construction method that addresses fabrication misalignment commonly found in cheaper aluminium window systems. Every window is designed to your specific requirements and made to your exact sizes.
Sheerline aluminium windows: the full specification
| Specification | Details |
|---|---|
| Fixed light sightline | 49mm |
| Beadless casement and French sightline | 59mm small outer frame / 72mm intermediate outer frame (on header if trickle vents are required) |
| Beaded sash sightline | 60.5mm / 73mm intermediate outer frame (on header if trickle vents are required) |
| Opener sightline | 60.5mm |
| U-value – double glazed | 1.4 W/m²K |
| U-value – triple glazed | 1.2 W/m²K – profile specific |
| Building Regulations | Part L compliant |
| Thermal technology | Thermlock® multi-chamber, polyamide thermal break |
| Security | PAS 24 security accreditation (2016 standard), with 6.8mm laminated glass upgrade for Secured by Design |
| Frame profiles | Contemporary, Contemporary Flush, Stepped and Stepped Flush |
| Glazing bars | Horizontal or vertical, Georgian grid or Art Deco layouts |
| Colours | 12 standard powder-coated finishes, plus bespoke CLASSIC RAL colours |
| Glazing unit | Double or triple glazed 28mm sealed unit |
| Warranty | 10-year manufacturer warranty and 25-year paint finish guarantee |
| Weather performance | BS 6375 air, water and wind classifications and Part Q |
| Lead time | Typically 4 weeks for supply only, although this can vary depending on season and project size |
Which window types can we make?
Casements are the most common window function design: side and top-hung opening lights at 59mm beadless or 60.5mm beaded in whichever layout matches the operational requirements.
French casements are also available where two sashes meet in the middle with or without a central mullion giving a 101mm sight line and 35.5mm for fixed lights.
How do Sheerline windows compare with Alitherm Heritage?
Choice and specification are what separate Sheerline Classic from the other heritage window system we make. Both use a stepped profile, but Sheerline Classic comes in four options, Contemporary, Contemporary Flush, Stepped and Stepped Flush so you can set the shadow line to suit the property and it carries the higher energy specification as standard.
Alitherm Heritage is built around a single ultra-slim profile, sized to fit inside existing stone mullions and original steel openings without altering the reveal. That makes it the one to start with on a listed building or a like-for-like steel replacement where the physical opening can’t be changed. Both ranges are accepted on conservation-led projects and neither will rust or rot.
How secure are they?
Every Sheerline Classic window carries PAS24 security accreditation (2016 standard), and the beadless sash removes the external bead that an intruder could otherwise work at from outside. Upgrading to 6.8mm laminated glass gives you Secured by Design accreditation, and it is worth specifying at ground-floor level.
Period property projects and planning
Sheerline Classic has been accepted on period, listed and conservation-led projects though final approval always depends on your specific property and the officer handling it. We can provide technical drawings and sightline details for a planning application and also a free corner sample so that the profile can offered for consideration. If you are early on in your project, our guides on what conservation officers look for and which windows tend to be approved are the better starting point.
How long does it take, and how do you get a quote?
We usually send quotations within 24 – 48 hours from receiving the initial enquiry but larger projects can sometimes take a little longer. Manufacturing runs to roughly 4 weeks for supply only though lead times move with the season and the size of the project. To quote accurately we need three things: approximate sizes, width and height; a basic layout or sketch; and the location of the project. Call 01535 603909 or send the contact form. We deliver nationwide and install across the north of England.
Real Sheerline Classic Projects
Explore our Sheerline Classic and heritage-inspired aluminium glazing projects, showcasing elegant designs that bring together traditional character and modern performance.
Leeds
Monarch House
Project details coming soon
Why homeowners choose Marlin
We are a family business, and we have been manufacturing aluminium windows and doors at our factory in Keighley since 2003. The business grew by applying the same quality standards and attention to detail we learned in aerospace engineering. All of the aluminium glazing we supply is made by us, not bought in as finished units.
“Excellent customer service from enquiry to delivery. Thank you to Hannah, Adrian and the team for going the ‘extra mile” – Caroline Dyson, Bingley
“We used Marlin for steel style doors and internal screens using Alitherm Heritage products on our recent self build project… Simply stunning” – Gareth Robinson – Hull
We are approved by Sheerline to fabricate the Classic system. Every window comes with a 10-year manufacturer warranty from us, and a 25-year paint finish guarantee from Sheerline.
Visit our Keighley showroom
You can see Sheerline windows at our Keighley showroom alongside the largest selection of steel-look windows and doors in the UK. Appointments are available Monday to Friday 9am to 4:30pm and Saturday 8am to 12 noon – other times by arrangement. Call 01535 603909 to book.
Helpful guides
Art Deco Windows: Styles, Features & Modern Replacements
Discover the timeless appeal of Art Deco windows in our buyer’s guide. Explore classic 1920s and 1930s designs, distinctive steel frames and modern heritage aluminium replacements that combine period style with improved insulation, security and durability.
Latest projects
HERITAGE WINDOWS AND DOORS
Classic Heritage Windows & Doors in Alderley Edge
HERITAGE DOORS
Barn Gym Conversion – White House Farm, High Catton, York
Frequently Asked Questions
Who makes Sheerline Classic windows?
The system is designed and extruded by Sheerline, part of Garnalex. The windows themselves are made by us in Keighley, to your design and your sizes, so quality control sits directly with us. The 10-year manufacturer warranty is ours; the 25-year paint finish is guaranteed by Sheerline.
Are these casement windows?
Yes. Side and top-hung casements are the most common operational function and heritage aluminium casement windows in the stepped profile are what most period replacements call for. Fixed lights and French casements are also available but for tilt and turn windows our Prestige system is used for this window type.
How energy efficient are they, and what glazing is that based on?
? The Classic window achieves an overall Part L compliant U value of 1.4 W/m²K with a 28mm double glazed unit and can achieve an overall U value of 1.2 W/m²K using a 28mm triple glazed unit with Krypton gas on certain styles which is A+.
What is the difference between beaded and beadless sashes?
On a beaded window an external bead holds the glass in place whereas the beadless version holds the glass in place without a physical bead. Also, the beadless version has a slimmer 59mm sightline, the internal corners look cleaner and there is one less point of attack. We offer beaded sashes with a sight line of 60.5mm as standard due to this being the most popular option and it provides the same PAS24 security accreditation as the beadless variant.
How are trickle vents handled?
Part F of the UK building regulations means most replacement windows now need to provide background ventilation. The Classic window system allows trickle vents can be introduced in the window sash but fixed windows need a 45mm add on to the top of the frame for the trickle vent which increases the sight line in this location. We always provide colour matched trickle vents so that they appear as discretely as possible on the frame work.
Can I have Georgian or Art Deco glazing bars?
Yes. Georgian-style 25mm bars can run horizontally or vertically, which is what makes Classic suit both a traditional Georgian layout and the strong horizontal proportions of 1920s Art Deco glazing.
What handles can I have?
Our full range of window and door handles is on the website, with the colours, finishes and patinas available.
Are there different cill sizes?
Yes, projection cills are available in 85mm, 150mm, 175mm, 225mm depths. Depending on the frame positioning within the reveal you can choose a cill size to suit your requirements.
How much do they cost?
Size, the number of opening lights, the glazing specification and the finish all move the price, so every quotation is worked out from your own sizes and layout rather than a list price. Send approximate sizes and a sketch and we will come back to you.
Do they need much maintenance?
No, and far less than timber or steel. There is no repainting, no rot and no rust. Cleaning the frames and lubricating the hinges and mechanical parts once a year is all it takes to ensure that everything looks and performs as it did when new.
Can I use them on a new build or an extension?
Yes, and people often do. The Classic system looks great for a contemporary application requiring slim framework on a modern or period new build, home rear extension or garden room.
Can I match the windows to my doors?
Yes. Sheerline Classic doors are built as an integrated range with the windows, so the profile and the colour carry across the whole elevation
Does the Sheerline system accommodate load-bearing bays?
Absolutely! The Sheerline Classic window system is designed to seamlessly integrate with structural support components, allowing you to enjoy slim sightlines without compromising your home’s structural integrity.
Window frames themselves (whether aluminium, uPVC, or timber) are designed to hold glass and not imposed loads unless additional integrated supports. Sheerline safely manages heavy loads using hidden engineered components inside the frame assembly, including heavy-duty bay jacks, engineered corner posts, and reinforced steel posts.
Come and explore…
Aluminium Bi-fold Doors, Sliding Doors, Contemporary Glazing, Aluminium Heritage Windows and Traditional Steel Replacement Doors
