The Window Depot
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Vertical Slider

We only use the Spectus Vertical Slider system. Survey after survey shows that the trade agrees it’s the best PVC-U sliding sash on the market.

The Spectus VS has proven itself in every type of project, for new builds, replacements and refurbishment. It’s technically superb, but its aesthetics are outstanding. It’s such a faithful representation of the timber box sash original that many planning authorities approve its use even in conservation areas.


The Spectus VS includes the authentic ovolo shape throughout – frame, bead, sash and cill. To recreate particular styles, there’s a choice of Georgian bars, sash horns and weather bars. Effective flush gaskets mimic traditional glazing. A deep bottom rail provides the all-important period look, and differently sized sash profiles give equal sightlines to the top and bottom sashes.


These sliding sashes are simple to open with smooth, reliable balance mechanisms. What’s more, both top and bottom sashes can tilt inwards so that the windows can be cleaned from indoors.

Thermal Performance

The system is a world away from the old, draughty timber sashes. These windows deliver 21st- Century standards of energy efficiency. There are woolpile seals for the sash and outer frame, and 24mm double glazing allows the windows to reach a WER of Band A.


The Spectus VS has a 128mm outer frame. This matches box sash dimensions for easier installation – cutting the time required to make good. Stairwells, larger projects and properties are no problem: windows can be up to 3000mm high and 1600mm wide.


The system is very adaptable. Options include:

  • Trickle or glazed-in vents
  • 150 or 210mm cills
  • Period hardware
  • Child safety restrictors
  • Standard or fully reinforced to Spectus recommendations
  • Compatible with off-the-shelf hardware


We offer a wide choice of contemporary and period colours in addition to classic white.


We only ever use the best components, and the Spectus VS system is highly accredited. It’s made entirely in the UK under an ISO 9001 Quality Management System using responsibly sourced raw materials.

  • Kitemarked to BS EN 12608
  • Certified to PAS 24
  • Approved by the British Board of Agrément
Casement Windows
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Bespoke Frames
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Coloured Frames
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Quality and service

We believe in quality, so we only choose the best suppliers, and our products conform to, and exceed, all the building regulations. We are a BS EN ISO 9001 registered business and have Secured by Design accreditation as well as numerous other standards.


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