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Windows by Harp

We offer our customers an advanced range of internally beaded double glazed windows incorporating a wide range of styles, designs and options from modern to traditional – and all with the same high specification as standard. A selection of colours and woodgrain effect finishes are available across all of our window ranges and we only install quality products from trusted names such as Rehau windows, Sheerframe sliding sash windows and Evolution Storm and Flush timber replacement windows. Our standard uPVC Rehau window is now rated A+!

Click on the options below to discover more detail about our different window ranges, features, styles and colours and download PDF Brochures from our Brochures and Videos page.

Quality and security as standard

Our Rehau casement window range offers better security features, more style choices and exceptional energy efficiency. Every product is tested, certified and manufactured to the very highest standards for proven quality and peace of mind. With a BSI-certified quality manufacturing system and Police approved security features as standard, we take quality further. With exclusive designs, a wider style range and more additional options, we take choice even further too.


Rehau white uPVC windows with feature rectangle leads.


The outward appearance of most replacement windows and doors can be almost identical, but don’t be fooled into thinking that all uPVC products are more or less the same! The quality of the materials, construction, overall design, locking and weather proofing systems can vary immensely from manufacturer to manufacturer. To help make you aware of the features you should consider when buying replacement uPVC windows, we’ve listed the main points to consider:

  • Fully reinforced 70mm frame depth with a 3mm wall thickness
    Reinforced with aluminium, for a stronger, improved thermal and acoustic performance.
  • Fully reinforced load bearing bay poles that can take a six ton workload
  • Fully welded system that is watertight
    Our casements incorporate a double sealed system with a neoprene seal, both on the outer frame and the vent.
  • Fully internally glazed
    All windows are internally glazed with a stylish ovolo bead so the units cannot be removed from the outside. 28mm overall sealed units in Planitherm Softcoft Total glass; energy efficient with a lower U value than Pilkington K.
  • Low level integrated gasket
    Much less visible and obtrusive, our integrated gasket gives the window a much cleaner appearance, in addition to providing an effective weather-proof barrier.
  • Concealed drainage system
  • Insurance rated multi-point locking system
    Locking in nine places around the window frame, incorporating an espagnolette shoot-bolt locking system with a claw lock and locking wedges.Casements have a secondary locking system where windows can be locked in a semi-closed position, aiding ventilation.
  • Energy efficient A+ rated windows as standard
    In addition to our Planitherm Softcoft Total glass sealed units, we can provide sealed units with warm edged spacer bars and argon filled units to increase thermal efficiency and improve your carbon footprint.

All these benefits are standard on our uPVC casement windows.

Colours and finishes that last

Fancy a change from white windows? Irish oak perhaps? Or maybe a sleek and contemporary anthracite grey? Our standard uPVC casement windows are available in a combination of smooth colours and woodgrain effect foils, all of which are durable, scratch resistant, can be easily cleaned and offer high performance and longevity in all types of weather conditions. We have profile examples of different standard colours available in our Bushey showroom. Other non-standard colours are also available on request but would require a longer lead time.


Rehau uPVC windows and doors in light oak and anthracite finish.


Sheerframe Environmental sash window

We specialise in the manufacture and installation of the Sheerframe® environmental sash window system. Available in smooth white, these vertically sliding sash windows are the perfect answer for period homes and period style properties, replicating the look of traditional timber sashes with the added heat and sound insulation properties of modern materials. Incorporating the very latest locking systems, adjustable restrictors and traditional timber aesthetics, our sash windows combine modern technology with traditional good looks for the perfect sash window.

The Sheerframe environmental sash window is acknowledged by architects, specifiers and planners as one of the most stylish designs in its class. A truly unique window that dispels the myth that traditional timber sash windows cannot be replicated in uPVC. It has even been approved for use within conservation areas across the UK and Ireland.

As a Sheerframe window fabricator, we offer total commitment to quality, in manufacturing,installation and service.

Sheerframe Sashes

Universal sash window

In addition to our Sheerframe sash window, we also offer our Universal sliding sash, available in white, cream, oak and rosewood woodgrain foil finishes. Superbly energy efficient window solutions coupled with the highest specification of locking systems, these box sash windows authentically replicate the look of timber but are virtually maintenance free. From six feet away it is extremely difficult to tell if the window is timber or uPVC.

Our Universal sash window is approved for installation in the Oxhey Village Conservation Area by Watford Council.

WIN SASH Universal white woodgrain

Close-up on our Universal sash woodgrain effect window profile and locks.

The Ultimate Rose sash window

Our Ultimate Rose window has been carefully designed with authentic sash details and the result is a class-leading window with woodgrain finishes, industry-leading slim sightlines, putty-effect glass lines, timber style mechanical joints and fully run-through sash horns. Features like these make all the difference, and many find it hard to spot the difference between the Ultimate Rose sash window and a traditional timber sash. As well as being virtually indistinguishable from real timber, the Rose Collection offers many advantages over timber, including increased thermal and acoustic performance, ease of operation, and low maintenance.

Two top of the range profiles to choose from – Storm or Flush fitting

Our top of the range windows, these are truly innovative, maintaining the look and feel of traditional wood but with all the advantages of state-of-the-art modern window technology. Handcrafted and tailor-made from only the finest materials, they offer outstanding energy saving, exceptional weather proofing and unequalled low maintenance. Two specifications of Evolution window are available – STORM 2 and the FLUSH system, designed to look just like a flush fitting timber window.

The Evolution Storm range successfully merges high-tech production values with hand-finished craftsmanship producing beautiful windows every time. It’s this attention to detail that is applied to every single aspect of your Evolution window that makes it different from the rest:

  • Unique timber style jointing system, new timber-look joints (no more weld marks!) and slimline proportions combined with an unparalleled attention to detail; you will find it hard to believe it isn’t wood!
  • An authentic “putty line” finish or Ovolo finish to Georgian bars ensures that your windows suit the style of your home to perfection;
  • Distinctive finishing touches such as feature period handles and working peg stays to add traditional style and elegance to your window;
  • The only manufacturer to offer windows designed to truly match the grace and refinement of genuine Tudor homes with their distinctive black and white elegance;
  • Accepted in conservation areas by a number of local authorities, Evolution windows have already won acclaim from the Heritage Association;
  • A comprehensive locking system with shoot bolts top and bottom and silver-finished steel bolts throughout the security systems for absolute consistency and effectiveness;
  • Quality that can only come from hand finished construction. You simply don’t get this on a standard uPVC window.
WIN EVO storm interior

Interior view of an Evolution window profile. Mechanical joints create a much more realistic timber-like look than a standard uPVC window.


Evolution colours and finishes

If you are feeling creative, the Storm 2 and FLUSH windows are available in a vast array of colours and with the exclusive ‘Kolorbond’ system we can create or match any colour you have in mind, the only restriction is your imagination!

If your tastes are more traditional, you can choose one of our popular wood-effect finishes in black wood, white wood, Tudor (black and white wood) natural wood, oak and cream. For more information why not download our range of Evolution brochures available on the brochures and videos page .

WIN EVO light oak flush

Evolution FLUSH profile in a light oak finish with single horizontal ovolo-putty external Georgian bar.


Enjoying a recent revival in popularity, aluminium windows have continued to be an attractive choice for replacement windows and doors. Harp Windows manufacture and install direct fix aluminium windows and doors, available in a choice of three main standard colours; white, black and brown, and up to 500 RAL colours available to order.

  • Thermally broken maintenance free, strong, durable and tough and fitted direct to brickwork just like uPVC;
  • The tough, protective, polyester powder paint gloss finish is guaranteed to maintain its good looks for many years to come and will only require an occasional wash down;
  • The slimmest and flattest possible sight lines coupled with clean, neat, elegant styling;
  • Will not warp, rust or need painting and are particularly suitable for bay windows where strong sections are essential;
  • Fully weather tested to a category C pass (severe) rating to BS6375 part 1, 2 and 3.

Harp Windows are proud to be an Aluk Beaufort Approved Quality Fabricator of aluminium windows and doors, and our comprehensive and versatile Aluk Beaufort product range is designed to provide solutions for all market sectors.

WIN ALI rear elevation house

White aluminium windows and Origin bifold aluminium doors.


Discover Europe’s leading energy saving glass

Research has shown that many homeowners assume that all double and triple glazing is equally energy efficient. In fact, there are huge differences in performance of different glazing configurations and it is the glass that makes the difference.

We install Planitherm Softcoat Total sealed units to all our windows as standard and we are members of the Planitherm Installer Network. Planitherm products are specifically designed to keep interiors more comfortable in the winter months and improve the home’s energy efficiency.

Planitherm products use a special coating to reflect heat from domestic heat sources back into the room, rather than allowing it to escape through the windows. At the same time, this coating allows free heat and light from the sun to pass through the glass, warming the room and further contributing to the energy efficiency of the windows and helping to reduce your energy bills.

As Europe’s leading energy saving window glass, Planitherm is the most efficient glass available today. Download our Planitherm guides and brochures from our Brochures and Videos page.

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  • Harp Windows (Watford) Ltd
  • 30 Aldenham Road
  • Watford
  • Hertfordshire
  • WD19 4AA


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