Honest John's Ranking System

Honesty, integrity and transparency.

How We Rank Double Glazing Companies – Our Recommendations and Scoring System Explained

How we rate and rank double glazing companies in an area

Honest John ranks double glazing companies according to a number of factors. To qualify, companies must have an online presence, so appear on Google Places certainly helps. The factors we consider include the following:

  1. Which? Trusted Trader Membership

  2. GGF, TrustMark or any other government endorsed standards

  3. Verifiable number of trading years - checked through The Companies House

  4. Online reviews from specific third party sites including Google, Trustpilot, Yelp, Review Centre and others.

    It is still important to keep in mind that there are individuals who earn a living by writing fake reviews for businesses.

How We Use These Factors

Why we chose the factors we consider.

Which? Trusted Trader

Which Trusted Trader.

Below is a quote from the Which? website:

As you'd expect from Which?, you'll be carefully assessed by our trading standards professionals. They'll give your business a health check and provide valuable advice and feedback to help you get and stay ahead. Once you've met our high standards, you can choose to join and be endorsed by Which? Trusted Traders.

Their assessment process includes the following:

  • A preliminary credit check to validate your business's financial health.

  • A check of customer references (chosen at random by the Which? Trusted Traders endorsement team from the 10 domestic customer details that you must provide)

  • A thorough examination of your business and administrative procedures, including checking certificates and insurance.

  • A visit from a Which? trading standards assessor and a face-to-face interview.

  • Before joining, applicants must also agree to the Which? Trusted Traders code of conduct, and to our terms and conditions and fees.

Which? have one of the most onerous conditions which you must fulfill before you join. For this reason, being a Which? Trusted Trader earns you the most points for a single factor in our ranking system: 8 points.

Falsely claiming to be a Which? Trusted Trader will deduct 8 points from your running total. This means if you had 0 points to begin with, and then were found to falesly claim Which? approval, your final point score would be -8 points.



As a GGF Member and having passed their criteria for membership, you automatically pass the criteria to become a TrustMark registered firm through GGF.


To become a GGF member you have to be trading for 3+ years. You also have to prove that you're financially viable and have to pass some background checks. This is #2 on our ranking criteria: 7 points.

These schemes also offer consumers an extra layer of protection, options and assistance for dispute resolution should the need arise.

False registration claims will deduct 7 points from your running total.

Verifiable Trading Years

Double glazing benefits.

According to the Office of National Statistics, only 41% of new businesses survive 5 years. What good is a 10-year guarantee on your windows if the business you bought them from survives just 5 years? The more established a business is, the more likely it is to have established systems that make it efficient. This is why 10-year trading history is 3rd on our list: 6 points.

These trading years have to be verifiable through the companies house, otherwise no points will be scored. That means sole traders and otherwise reputable white-van men will not be able to score in this category, unless they are registered as Limited Companies.

We like to look at how long a company has been in business, as this can give an idea of a company’s stability and financial viability. It also presents more opportunities to see how they deal with clients by considering their local reputation.

double Glazing generally comes with a 10 year guarantee. In an ideal world, if something went wrong with your windows, you would pick up the phone and have it rectified at no additional cost. But what if the company has gone out of business? You want the company you deal with to last, at least for as long as the guarantee. This is why we consider a 10-year trading history.

False claims will lead to a deduction of 6 points from the running total.

Online Reviews

Online Reviews.

As mentioned before, reviews can be faked. There are several articles outing big companies for buying reviews. Separating real reviews from fake ones can sometimes be impossible if they're done well enough.

We try to consider reviews from a specific location if these are available. This is because a national company's reputation can vary from city to city, so it makes sense to take location-specific experiences into account. Where reviews from specific locations are not available we will use the available aggregated scores.


Trustpilots placed at #4 of our 8 ranking factors. This is because of their size and the work being undertaken to counter fake reviews.

A business will score 5 points if it has reviews averaging 60% or better. Similarly, the business will have 5 points deducted from its running total if review ratings fall below this level.

Trustpilot combating fake reviews


Yelp placed at #5 of our 8 ranking factors. They have an automated review filter that suppresses 25% of suspicious reviews, although these may go too far by filtering out legitimate reviews.

Yelp reviews averaging 60% will score a business 4 points in our ranking system. If the reviews fall below this level then 4 points will be deducted from the running total.

Yelp Fake Reviews

Google Reviews

To leave a google review you need a google account, which also requires a legitimate mobile number to verify your account. This was put in place to combat spam, which is ultimately what we are discussing here. However, you can open several accounts with a single number.

Once a Google Review is left on your Business Page it is difficult to have that review removed, fake or otherwise. This can be a problem when a business is unfairly targeted with bad reviews.

Google Reviews place at #6, earning a business 3 points for reviews averaging 60% and -3 points for falling below that threshold.

The Review Centre

There are several cases where consumers have been contacted to provide proof of purchase before a review is allowed to stand. Even then their system is far from perfect: 2 points for reviews averaging above the 60% threshold and -2 points if below.

Other Third Party Review Sites

If a double glazing company has ratings from any other third party websites then we will consider those as appropriate and add points thusly: for a company that averages a rating of 3/5 and above (or the numerical equivalent), we will add 1 point to its running total. Falling below the threshold will result in the deduction of 1 point from the running total.

Highest Possible Score

The highest possible score that can be attained is 36 points.

How We Pick The Double Glazing Companies We Recommend

Double Glazing Company Selection Process

After reviewing all relevant factors and adding up points, we sort the companies considered from highest rated to lowest, in the given city or region. Be sure to complete your due diligence and exercise caution, regardless of anyone’s recommendations, even ours!

Please note that our recommendations are also part of an ongoing project – it’s certainly possible that there will be new double glazing companies or changes of ownership occuring over time. If you know of any significant changes in your area then click here to let us know!

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Help Other Consumers – Spread the Word!

Did you have a good experience with a double glazing company? Had a bad experience or disagree with a recommendation? Help other consumers by leaving reviews on any third party websites – this will also help us to keep recommendations and ratings updated.

Your experience can help point people to a good company and keep them away from dodgy ones. If you found the information from Honest John helpful, we’d also love it if you helped spread the word about our recommendations and the tools we provide to help consumers like you!

Be a Consumer Champion and spread the word: Use the share buttons on your left!

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Do You Own and Operate a Double Glazing Company? Help Us Help You Get in Touch with Consumers and Customers

Don’t see your company listed here? Want to add some information you think is missing or would be helpful? By all means, send us a message and let us know. Communication is currency when it comes to building trust - the more accurate and useful information consumers are able to get their hands on, the more likely it becomes that they will decide to transact with a company.

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