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Ultra Slimline Sliding Door

The Landscape is Changing 

21mm Frame - Alpine Aluminium's AP Infinium Ultra-Slimline Sliding Door 



slimmest sliding door system

Only 21mm Frame Width
The Slimmest in the UK

sliding door handle

Lateral Locking Handle
With Concealed Mechanism

fastest sliding door turnaround in uk

7 Day Turnaround
Fastest Available in the UK

fully concealed outer frame sliding door

Fully Concealed


The Slimmest Aluminium Sliding Door in the UK


With a profile width of just 21mm, Alpine’s AP Infinium aluminium sliding door system is capable of supporting expansive panels up to 3m in width and 3.5m high - available as either a double or triple track. With a U-value of less than 1.0 (on our triple glazed option), the AP Infinium satisfies even the most stringent Passivhaus requirements in thermal efficiency.



Don’t Miss our Introductory AP Infinium Sliding Doors Offer!


Simply call 0113 253 0254 or complete the enquiry form to instantly secure your 10% Discount, 15-year guarantee and FREE Specification Upgrade on our AP Infinium Ultra-Slimline Sliding Doors 


get a free quote

ultra slim sliding door contact details

Register Your Details Online Today to Reserve Your 10% Discount and Alpine NOW Upgrade!

ultra slimline aluminium sliding door system in leeds

AP Infinium Ultra-Slimline
Aluminium Sliding Door


With its fully concealed aluminium outer frame and sash, flush thresholds and simple operation, the AP Infinium’s considered design impresses from every angle. Ironically, its most remarkable design feature barely catches the eye. The impossibly thin 21mm sight-lines creates the illusion of a large endless space, with a seamless floor-to-ceiling panoramic view.



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  AP Infinium Sliding Door
  Design Features

  • Fully concealed outer-frame
  • U-values lower than 1.0 W/m²K
  • 21mm visible sightlines
  • One or more opening panels
  • Extensive range of configurations
  • Floor-to-ceiling panoramic view
  • Incredible width dimensions up to 3000mm
  • Expansive height dimensions up to 3500mm
  • Supports up to 400kg panel weight



ultra slim sliding door design features

Simply register online today for a 10% discount,
extended guarantee and upgraded spec on your AP Infinium order


If you are looking for aesthetically stunning design combined with incredibly thermally efficient bi-folding doors, then get in touch with one of our friendly sales team today or visit us at our showroom in Leeds. An Alpine Sliding Door Specialist will be able to help you with a wealth of useful advice whilst providing you with a no-obligation quote based on your individual requirements as well as securing your 10% discount, 15 year guarantee and FREE Alpine NOW upgrade. 

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folding sliding doors

sliding doors

roof lights

roof lanterns

The slimmest aluminium sliding door
system available in the UK


Manufactured and hand finished at our specialist factory and available to view at our showroom in Leeds, Alpine’s AP Infinium slimline aluminium sliding door system is not only the slimmest available in the UK, but able to support panels of up to 3m in width and 3.5m high and available as either a double or triple track. With a U-value of less than 1 (on our triple glazed option), the AP Infinium satisfies even the most stringent PassivHaus requirements in thermal efficiency.


However, it is aesthetics that ensure the AP Infinium stands out from the crowd – the outer frame is fully concealed and with a central interlock of just 21mm, the Sliding Doors provide a virtually uninterrupted view of the outside landscape from the comfort of your home. In addition, a floating corner post is available, creating an even larger opening space. Accompanied by lengthy guarantees, incredible air and water tightness, and security robustness, the AP Infinium is truly the leader in Aluminium Sliding Doors looks and performance on the market today.


Request a copy of our AP Infinium overview brochure and receive a 10% discount!


Simply request a copy of the AP Infinium overview brochure by downloading, calling or completing the no obligation enquiry form today, and receive a 20% discount, extended guarantee and FREE Alpine NOW! Specification Upgrade on any subsequent order.


free brochure

Alpine Aluminium AP Infinium Brochure



door upgrade option

Alpine Now - Our Priority Upgrade


Alpine Aluminium understand that it is not just a bespoke aluminium product that you require, but also a bespoke service. From our manufacturing centre in Leeds, we are able to achieve the fastest turnaround currently available in the UK. In addition, we have a wide range of Alpine Approved options and components which will ensure your doors, windows or roofs exceed all expectations with Alpine NOW! 

Alpine Now Upgrade Features:

upgraded glass for better efficiency

Upgraded Thermal Glass


Upgrade today to improved
thermal efficiency with the 4S
glazing system

5 day turnaround doors and windows5 Day Turnaround


From 7 days to 5 days.
The fastest in the UK!

15 year guarantee15 Year Guarantee


Extended guarantee from
10 years to 15 years


colour matchingSeamless Colour 


Perfectly seamless look with matching RAL7016 gaskets, handles and hinges

any colour bifold doors and windows
ANY Colour


Choose ANY colour
to match your home

bifolding doors


roof lights

roof lanterns

alpine approved doors and windows

Consistently ensuring exceptional quality


Alpine Aluminium doors and windows are manufactured using quality materials sourced from carefully selected suppliers. On delivery, every part or component is meticulously checked by hand to ensure they meet Alpine’s quality standards. Should they pass, they become officially ‘Approved’.


Alpine retain full control throughout the manufacturing and finishing processes and as a result, have the capability to achieve an exceptionally fast product turnaround. In addition, Alpine offer a 15 year guarantee, giving you all-important peace-of-mind whenever you see the ‘Alpine Approved’ stamp.

A Breath of Fresh Air


Everything we do at Alpine Aluminium is tailored around you. In contrast to many sliding door suppliers, as a UK manufacturer based in Leeds, we can offer a product and lead-time that fits your requirements. From an unrivalled range of specification options through to express manufacturing timescales, Alpine are truly a breath of fresh air in the sliding doors industry.

slim sliding doors
thermally broken sliding doors
ultra slim sliding door

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