• Showroom & Head Office

    01923 231 111


Having double glazing installed can often open a minefield of questions and concerns. Here and throughout this site, we hope we’ve managed to answer most of your questions and address any concerns that you may have.

Q: What makes you at Harp so different from the rest?

  • Established back in 1989, we have been continuously trading under the same name since that time;
  • We’re family owned and family run and are experts in our local market;
  • We’re fully committed to providing a quality local service that’s friendly yet professional, and provides real value for money;
  • We believe in offering our customers a CHOICE of high quality products;
  • We NEVER engage in any high pressure sales tactics and fully respect our customers’ privacy at all times.
  • Since March 2014 we’ve been members of Checkatrade where reputation matters. Read our customer reviews at http://www.checkatrade.com/HarpWindowsLtd/Reviews.aspx
  • Finally, last but by no means least, we are fully endorsed as a WHICH? Trusted Trader AND Hertfordshire Trading Standards Approved.

Q: What sort of guarantee do you offer on your products?

We offer a comprehensive ten year insurance backed guarantee on all our installed products that is administered by the Consumer Protection Association. In the unlikely event that you should have any issues with your products within this guarantee period, we’ll come out and fix them for you. Free of charge. That’s complete peace of mind for all our customers.

In addition to our comprehensive guarantee, as a WHICH? Trusted Trader we can also offer all our customers the benefit of the WHICH OMBUDSMAN SERVICE. On hand to offer extra peace of mind, The WHICH Ombudsman Service provides independent dispute resolution and is free to any customer of a WHICH? Trusted Trader. It goes without saying that we hope you never have to use this service!

Find out more from the following websites:

Q: I’m very concerned about security. What reassurances can you offer me?

With every window or door installed by Harp, comes the peace of mind in knowing that your home and your possessions are protected by products that are proven in their ability to withstand forced entry. Our uPVC and aluminium casement windows and residential doors, French doors and composite doors all have Secured by Design options available for you to choose. Secured by Design is a range of national Police projects committed to home security, and all accredited products have been tested to the very latest BS:PAS security standards published by the BSI. Please feel free to contact us for any further information about the security of our products.

Q: I live in a period property and I’d love the benefits of double glazing, but can’t fit just normal double glazed windows because I’m in a conservation* area. What can I do?

We install the Ultimate Rose sash window, virtually indistinguishable from timber sash windows, yet they are top spec, maintenance free, double glazed, easy clean and high security. You even have the option of an authentic style Georgian glazing bar and arched tops. Our sash windows have been approved for the Oxhey Village Conservation area.

We are also official selected partners for Evolution Windows. They maintain the look and feel of traditional wood in the style of Georgian and Tudor but have 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. Our Evolution windows have received approval for the Roe Green Village Conservation area.

Our sash windows and Evolution windows have been installed in conservation areas, and are the ideal choice for the discerning homeowner who does not wish to compromise on quality or choice.

Finally, we install Bereco timber windows in both lipped and traditional flush casements which can also be an option for Conservation areas and listed buildings.

*If you live in a conservation area, you may need planning permission to replace your original windows. Contact your local authority for details.

Q: Can I look at some previous installations that you’ve done?

Absolutely! We have many photographs that have been taken during installations and we are more than happy to email you photographs of installations in your area or that have a similar specification to your property or window type. We can also provide you with locations of recent installations which you are able to view. In addition, you can also see the results of our customer satisfaction surveys in our Watford showroom and see genuine up-to-date customer reviews on our Checkatrade page.

Q: Do you make aluminium windows and doors?

Yes! We manufacture windows and doors using the market leading Aluk System which is installed direct into brickwork. As an Origin Global Trusted Partner, we install the full Origin Global Premium range of aluminium windows, doors and bifold doors. You can download all our aluminium brochures from our Brochures and Videos page.

Q: Are your windows energy efficient?

Yes! Our Rehau Total 70c uPVC casement windows are available with an A+ rating as standard. Evolution windows are also A+ rated and our Ultimate Rose box sashes are A rated, as are our Kömmerling casement windows. Your quote/contract should always clearly state what energy rating your products are, but we are happy to clarify in all instances.

Since 15th June 2022, new Building Regulations have come into effect that mean our windows and doors have to meet even more stringent energy efficient measures. Using a combination of the window/door profile, with specific double glazed sealed units (for instance, soft-coat glass, argon gas filled units with a warm-edge spacer bar), we can meet and exceed the latest minimum standards. So that’s good news for your home and good news for the planet too!

Q: What does this rating actually mean?

Simply put, this will determine how well a product will perform the functions of:

  • Helping you contain and conserve heat within your building in the winter;
  • Keep out the wind;
  • Resist condensation;
  • Contribute to improved sound insulation.

For instance, our REHAU TOTAL 70c window has been awarded an A+ WER licence from the BSI. The BSI Kitemark scheme for Window Energy Ratings (WER) is based on the approved document L1B of the Building Regulations which came into force on 1st October 2010. Since then, Building Regulations were recently updated on the 15th June 2022. The latest updates stipulate that replacement windows and doors must meet the following minimum standards:

  • Windows = U-Value of 1.4W/m2k or WER B
  • Doors (glazed area > 60%) = U-Value of 1.4W/m2k or DSER C
  • Doors (other) = U-Value of 1.4W/m2k or DSER B

The BSI Kitemark scheme for WER provides a quality assured process and supporting audit trail from simulation of the WER through to installation and is therefore accepted by Building Control Bodies. The WER Kitemark label can be used on the product down the supply chain ensuring that retailers and installers can use Kitemark Window Energy Rating certified windows. Find out more at the British Standards Institute website >>

NOTE: There are different minimum standards for timber windows and doors. Please don’t hesitate to chat with us if you require any further clarification on this.

Q: I have heard that Building Regulations have changed – what does this mean for me, the customer?

New Building Regulations came into force on the 15th June 2022. There are two main parts of the new regulations that will affect installations that we undertake:

  • Document L refers to energy efficiency measures. This requires that new windows and doors meet the latest minimum energy efficiency standards.
  • Document F refers to ventilation. This requires that homes meet minimum ventilation standards when new windows and doors are installed.
  • This means that for most installations, to meet the new requirements you will need to have trickle vents installed in your new windows. We have a handy document FAQs document on these latest Regulations, that you can download here:
    FAQs on the latest Building Regulations June 2022

    Q: How long will it take for my windows/doors to be installed?

    For standard installations we usually quote a lead time of around 6 weeks. However in reality, installation can often be quicker than this, it depends on the time of year and our current workload. If a customer needs their installation completed by a certain time, we will always do everything we can to ensure that takes place.

    Q: I wanted timber windows but they are so expensive! What is your timber alternative window?

    This is the Evolution Storm™ and Flush range of timber alternative windows. These A+ rated windows truly stand out with a quality of finish that is unsurpassed:

    • The frames are all butt jointed using the same process of manufacturing a timber window; there no welded corners on the outer frames like in a standard uPVC window;
    • Windows have a timber grained finish in white, cream, black, natural wood or any colour that you require;
    • The internal edges on the outer frames are all ovolo with the exact detail of a timber window;
    • The external edges are a pencil round finish with a putty line edge to the glass;
    • Traditional style handles and peg stays complete the authentic look.

    You can see examples of our Evolution installations in our gallery, or come and see our display windows in our showroom and appreciate the difference for yourself.

    By the way, we do install Bereco timber windows in both lipped and traditional flush casements which can also be an option for Conservation areas and listed buildings.

    Q: What sash windows do you do?

    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.

    If you want to maintain the authentic look of sash windows but are on a budget, you may wish to consider our EcoSlider sash windows. Thermally efficient and environmentally friendly, they mimic the aesthetic appeal of a classic timber vertical slider but deliver all the benefits of a modern uPVC system, giving you the best of both worlds.

    Q: I’d like someone to give me a quote but don’t want to be hassled with high pressure sales or annoying salesmen!

    Please don’t worry, we never engage in these tactics. We spend around 30-40 minutes with you, discussing your options and measuring up; we will then provide you with a quotation. We don’t keep ringing you up or hounding you for a decision and we fully respect your privacy at all times. That’s a promise.

    Q: Who will fit my windows? Do you have your own teams of fitters or do you subcontract?

    We don’t subcontract; we have our own teams of fitters, many who have been with us for a considerable number of years now. They will treat you and your home with both courtesy and respect and will even clean up after themselves. We receive a lot of complimentary feedback about our fitters, see our testimonials page to see what our customers have said.

    Q: What happens if I have a problem after installation?

    Simply give us a call and we’ll send out our service engineer to rectify it for you. If you’re within your ten year guarantee period there will be no charge for this service. As a WHICH Trusted Trader,  we also offer a clear and transparent complaints procedure – we hope you will never have to use this of course! In the highly unlikely event that we are unable to resolve your complaint using our own complaints procedure, as a Which? Trusted trader we use Ombudsman Services Ltd for dispute resolution.

    If your question hasn’t been answered here, please do not hesitate to contact us – we’re here to help!

    Endorsements & Reviews

    Watch Our Videos

    Window unit replacement to a sash

    10 Verified Review

    Fantastic service from beginning to end. Local showroom in Watford with a super variety of windows and doors The fitment of the sash for my son's bedroom, best decision. Quality window and beautiful finish Paul and Miles are polite and friendly. Paul is a master at his job and Miles is super when finishing and completion. Thanks guys and thank you Harp Windows

    Location: WD25September 2023

    Replacement front door

    10 Verified Review

    All appointments on time. Advice useful when choosing design. Fitted in less time than expected.

    Location: WD23August 2023

    Bay Window Replacement

    10 Verified Review

    I have to say I have been impressed with HARP from start to finish. I was guaranteed the best price from John at the beginning, There was no hard sell or tricks, Just simple and honest. I ordered 1 window to replace my old bay which I was advised would take 6 weeks from ordering. My window arrived slightly earlier than anticipated and was fitted without delay. The fitting team worked in a clean and tidy manner, were punctual and had a great attention to detail.

    Location: WD24July 2023

    Supply rear door.

    10 Verified Review

    Excellent service, most helpful and friendly. Highly recommend.

    Location: BH10May 2023

    2 x casement windows

    10 Verified Review

    Very pleased with product and workmanship. All done with no fuss and no mess. Brilliant job. Billy even hoovered up afterwards !

    Location: WD18May 2023

    New windows and doors

    10 Verified Review

    Excellent service from both the showroom staff and the fitting team . Quality of the windows and doors is very good , and would highly recommend this company

    Location: WD24April 2023

    Read all 250 reviews

    • Harp Windows (Watford) Ltd
    • 91-93 St Albans Road
    • Watford
    • Hertfordshire
    • WD17 1UL



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