Double Glazing in General

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Double Glazing in General

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Review of "Double Glazing in General"

published 02/07/2004 | SuperSpy
Member since : 23/05/2003
Reviews : 14
Members who trust : 3
About me :
Pro Low maintenance, secure, energy efficient, adds value to your home
Cons Serious trouble if you get it wrong
After Sales Service

"Cheap and tearful?"

So you can’t put it off any more. The old windows really have to go. You’ve heard the horror stories of the unscrupulous sales reps, the cowboy fitters and the non-existent customer service. Your ability to choose one window from another is limited to what looks nice in the brochure. You are bombarded with cold phone calls, leaflets through the door, amusing commercials on the radio, and studying the Yellow Pages only adds to the confusion. Where do you start? How do you decide which companies to get quotes from? And worst of all, how do you survive the visit of the dreaded double glazing salesman? How much should I budget for, and should I consider finance. If you survive all this with your sanity intact, you then have to decide which windows to actually buy.

There are two very simple steps to solving all these problems:
1 Win the national lottery
2 Ring Everest.

However, if step one proves to be elusive, my guide may help you through the minefield you are about to step into.

DG companies boil down into three groups. The big national companies, many of which may be household names, smaller local DG specialists, and local general builders. Unfortunately there are no hard and fast rules here. You can have triumphs or disasters from all categories, but long term satisfaction and peace of mind tends to come from the companies who have already been in business for longer than the guarantees they give. Personal recommendations are a popular starting point, but taken in isolation, may only be anecdotal. Besides, some people just love to complain about anything, whereas others are so easy to please, their opinions may not be objective enough to be of any use.

The only thing for it is to do your homework. Collect as many opinions as you can. Look around your neighbourhood, don’t be afraid to knock on a few doors and ask if the homeowner would recommend the company that installed their windows.

Draw up a shortlist of four or five companies drawn from the three categories I mentioned above and then check if they are members of the Glass and Glazing Federation. You can phone them on 0207 403 7177 or visit their web site at

This extract from their web site explains what they do and the free services they provide:-

GGF members have been vetted to ensure quality of service: this vetting process includes making a site visit to the company's premises, checking three year's of their accounts and taking up references.
A Code of Good Practice & Glazing Manual
All our members work to A Code of Good Practice and to the Technical Standards laid out in the Federation's Glazing Manual.
Customer Charter
GGF has a Customer charter offering consumers:
advice on where to buy
advice on what to buy
safeguarding of purchases
quality service at all times
continued customer care.
Free Conciliation Service
The GGF also provides a free conciliation service, should a customer and a member company not see eye to eye over work carried out. In the rare cases that this does not work, the GGF has an independent arbitration scheme run by the Chartered Institute of Arbitrators.

Do not necessarily accept the GGF logo on headed notepaper as proof that any DG company is currently a GGF member. Some companies, including a big well known one (BAC) are no longer members since they have ceased trading, started up again under a slightly changed name. The guarantees given by these companies are consequently not to be trusted. Incidentally, I know of a BAC salesman who keeps with him an advert from a local free newspaper that insinuates that Everest advertise for contractors to carry out installations. He shows it to prospective customers in order to undermine a rival company. I can only assume that the salesman placed the advert himself for that very purpose.

Checking with the GGF should weed out the less reputable or unestablished companies and help you decide on your short list with some confidence. But they vet the companies, not their staff, so it may not be of much help when you step into the ring with the wily sales rep.


Dealing with a DG Salesman in your home can be a worrying prospect if you know nothing about the wide variation in the quality of the product and fitting techniques of the installers, not to mention the spiel of the salesman himself.

A golden rule is that you should have a pre-prepared list of questions. This op should help you write one. If he answers any them as part of his patter, note down what he says. At the end, if you have anything unanswered, ask him open questions (do not put words in his mouth) from your list and note down his answers. This will not only put you in control, but also give you a tool to help you make comparisons between the merits of the products of each company you obtain a quote from.

The Appointment
Broadly speaking the format of the appointment is as follows:- The salesman will measure your windows and discuss your requirements, present a sample, explain any finance and work out the price, then finally, present the price, which is usually where the fun begins. If you don’t want the ‘hassle’ or can’t afford the time and just want a price, then you are doing yourself a disservice. It is essential that you see what you are paying for. If a salesman is keen to demonstrate his wares, it is a good sign. If you just want an estimate it may be of little help. It may not be very accurate, you will have no idea what is included and you will have to find time to see what’s on offer and get an accurate quote before you buy anyway.

The measurements a salesman takes are accurate enough only to be able to give you the correct price. If you decide to buy, It is essential that you then receive a visit from a qualified surveyor in order to take the exact dimensions and check for any structural considerations that the salesman may have missed. This is very important since your windows must fit as closely as possible to the surrounding brickwork.

It is expensive to manufacture to a fine tolerance and the windows may take a little longer to fit, but the alternative is that your windows may be held in place with nothing more than some DIY ‘expanding foam’ covered by a strip of silicone. The whole unit can then be removed from the outside with a crow bar or a shovel. If loose fitting units are bolted in place, there is a risk that the bolts may be over-tightened, damaging the frame and compromising the effectiveness of the sealed unit.

Ask about the fitters
Always ask the salesman about the fitters and their methods:
 They should never remove a window unless they have time the same day to replace it.
 Any local damage sustained the brick and plaster should be made good.
Covers and dustsheets should be used throughout the property, not just where the work is being carried out.
 All old material should be removed from site without a stopover on your lawn.
 Fitters should have trade qualifications as well as being trained and employed by the company. This is important since contractors may not necessarily care about either the quality of their work or the state in which they leave your property.
 They should clean and tidy up before they leave.
 They should allow you to inspect the installation to your satisfaction before signing anything and paying any balance due.
 The fitting should also be part of any guarantees.

The more reputable companies will even send in an inspector after the fitters have gone. Ask the salesman if his company does this.

The Surveyor
As mentioned earlier, the surveyor plays an essential part in the process for the benefit of the customer.
However, the visit of the surveyor can sometimes carry a sting. A classic “con” regularly employed by one of the UK’s larger companies and copied throughout the industry…. (A close relative of mine had exactly this experience with Anglian recently) . . .

You get such a cheap price that you decide to sign an order to proceed (a legal obligation for you to have the job done) and you pay a deposit. Next to the price on the order form, or somewhere in the small print are the infamous words “Subject To Survey” or even STS. The surveyor duly arrives, assesses the work, scratches his head, and delivers the following news…“I’m really sorry about this, I don’t know what the sales person has done, but he has left off X, Y and Z from the order – The job simply can’t be done for this amount – We’ll either have to cancel, or you will have to pay the extra to cover the X, Y & Z the sales person has “unfortunately” omitted”. By this time, you are so tired of shopping around, and the price increase is up to around the other quotes you had previously – So you do one of two things:
1. Do what the errant company is relying on – Pay the difference, so they have secured another order in the face of their competition or….
2. Tell them that they employ incompetent sales people and show the surveyor the door.
At this point, some companies will not pursue the sale, but others (and this happens daily), will enforce the legal agreement you have signed in the comfort of your own home, saying, “You should have read what you are signing”. Legally, it is very difficult to get out of this situation, so the moral is – Read the terms and conditions on the order form. Ensure that your deposit, if paid, is returnable if the price is substantially altered.

While on the subject of the small print, you are legally allowed to cancel within a statutory seven days if you buy anything ‘on the doorstep’. But if you invite a salesman into your house and sign an agreement, you are legally committed, unless there is something in the terms that gives you seven days grace anyway. Always ask for this.

All windows are pretty much the same aren’t they?
With regard to the windows themselves, the variance in quality and therefore price is vast. Since the time when PVC-U double-glazing was a new phenomenon, advances in technology have had both positive and negative effects on the product. On the positive side, there have been advances in the effectiveness of welding the joints, the design of the internal cross sections that house the steel reinforcement and improved glass coatings. On the negative side, the introduction of recycled PVC-U and cheap and nasty DIY fitting aids have meant that just about anyone, even on the most meagre of budgets, or sometimes no budget at all, can have double glazing installed.

This has lead to a polarisation of companies at one end of the market or the other. Without doubt, over the last decade since the great council house sell-off, the highest turnover has been at the cheaper end of the market where companies often compete on price alone.

Recycled PVC-U
May look OK on the sample, but does not retain the hard shiny coating, allowing for dirt and grime to discolour it. Once this happens, you can not clean it or repaint it. You are stuck with grotty looking windows.

Depth of the Frame
Your old timber window frames are probably 3 inches deep (inside to outside). If you replace them with standard PVC-U units of 60mm depth you will be left with either a gap on the inside, or outside which could leave a white line around your brickwork where the old frames were painted. A full 70mm depth is recommended since this also allows for stronger steel reinforcement and more internal cross section compartments that will restrict heat loss through the frame. It also improves rigidity without deepening the width of the frames, which would reduce the amount of glass.

All salesmen will tell you their window frames are steel reinforced. But in the small print it may say ‘where appropriate’ or ‘above a certain size’. Sometimes it may refer only to the outer frame and not an opener, in which case the locking mechanisms may only be screwed, or sometimes riveted, into a few millimetres of plastic. And what about the steel? What kind of steel is it? Galvanised steel is recommended. Does the shape matter? Yes. Some frames have a single bar of steel, others angled for extra strength, but the best are box-sectioned and even corrugated.

The reinforcement of PVC-U windows is an unseen but vital component. Any major building work on your home will put a strain on the surrounding walls, effecting plaster and even internal door frames. It is essential that any window replacements are tightly fitting and sufficiently reinforced to keep movement to an absolute minimum.

With regard to the actual glass its self, government regulations stipulate minimum insulation standards. If a salesman talks about ‘Document L’, this is what he is referring to. Pilkington ‘K’ glass has the special coating that conforms to this standard. See my notes under Building Regulations regarding FENSA.

Toughened (safety) glass should be fitted as standard where the glazing panel is low enough to the floor to be a danger to toddlers. This glass will shatter harmlessly if broken. Not to be confused with laminated glass. This is a 2mm acrylic sheet built into a 4mm glazed pane making a 6mm thickness. This is always worth considering when security is an issue particularly on glazed back doors.

No window is 100% secure. If a burglar has the time, the tools, and the incentive to get in, he probably will. The best you can do is make sure that your windows are better than your neighbour’s, and fit an alarm system or buy a big black Alsatian.

The Sealed Unit
The effectiveness of the sealed units also varies. Some cheaper units have to be ‘gas filled’ in order to reach the standard of the better quality windows. Regarding the distance between the panes, there is a trade-off between heat insulation and sound insulation. If you live under a flight path or on a busy road and noise pollution is you main concern, then consider secondary glazing. This gives a much deeper gap between the inside and outside glass surfaces. The optimum distance for a double glazed sealed unit is 20mm between the inside surfaces of two sheets of 4mm glass.

One of the biggest problems with double glazed sealed units is that they will eventually suffer from condensation forming between the panes. Only one company gives a lifetime guarantee as standard and you can guess who they are. In the early days, this was such a problem in the industry that the sealed units were fitted into the frames from the outside (externally glazed), so when they had to be replaced, a fitter would not have to make an appointment with the homeowner. He could just turn up, remove the ‘clipped-in’ units and replace them. Of course this caused a major security risk since any burglar could remove the units just as easily to gain access. It is essential that any windows you buy are internally glazed.

I think I’ll have those nice ones with the rose petals
Anyone who simply chooses their windows from a brochure because they look nice and are cheap will be totally unaware of any of the vital points that I have discussed above. What a window actually looks like with regard to the fancy appendages that are available is entirely down to personal taste (for which there is no accounting) and whether the style of the house is taken into consideration, (which in many cases it is not). Many options are available, rectangular, diamond, or many other fancy lead designs are available, often with coloured glass (Stick-on film is generally better than spray painted). Georgian bars, between the panes (tacky) or on both outside surfaces (authentic but more expensive) are also widely available. Arched corners and woodgrain effect are all cosmetic options, but one thing many people do not take into account is the different widths of adjacent opening and fixed frames. Sometimes referred to as ‘sight lines’.

You see examples of this everywhere and in large bay windows with a mixture of fixed and opening fanlights and casements they look absolutely awful. It can be rectified, usually at extra cost, by an extra width of PVC-U around the edge of the fixed panes. Ensure that your quote includes these if you require them.

Not to be confused with warrants. A warrant usually involves the homeowner being obliged to perform regular maintenance in order for the warrant to remain valid.

Guarantees are usually for 10 years, so be especially wary of a small company that gives a 25-year guarantee. It is not unheard of in the industry for companies to cease trading and start again under a different but very similar name, even some well-known ones. In which case, any guarantees they gave will be worthless.

Some smaller companies or local builders who do not manufacture their own units, may get them from manufacturers who may only give a 5 year guarantee or maybe none at all. The units may then be given a standard 10-year guarantee by your DG company who will merely cross their fingers. Another thing to beware of are guarantees that do not include the fitting.

Building Regulations
As far as I am aware, building regulations on double-glazing apply to two issues. Firstly, the heat retention quality of the glass. This is a government requirement for reasons of energy conservation.

Here is an excerpt from the FENSA web site
FENSA stands for the Fenestration Self-Assessment Scheme. It has been set up by the Glass and Glazing Federation (GGF), with Government approval, in response to the new Building Regulations for England and Wales
From 1 April 2002, all replacement glazing in dwellings will come within the scope of the Building Regulations. From then on, anyone who installs replacement windows or doors will have to comply with improved thermal performance standards.
When having their windows and doors replaced from this date homeowners must ensure that they get a certificate form Local Authority Building Control or have the work completed by a FENSA Registered Company.

If a sales rep talks about ‘K’ Glass or Document ‘L’, this is what he is referring to.

Secondly, from a safety point of view in case of fire, an escape hinge (sometimes known as an ‘egress’ hinge) must be fitted to all habitable upstairs rooms. A normal hinge on a double glazed unit will open up to a third of the way from the edge of the frame. This makes it easy to clean the outside of the window, but can restrict exit in case of an emergency. An egress hinge opens from the edge of the frame to allow wider access. Better quality ones will also allow for outside cleaning by use of a sliding mechanism..

You will most likely be offered a finance package. I am not a financial adviser, but these are the things to consider.

Cash is NOT king. Discounts for cash may not be forthcoming unless a very heavy deposit is required, in which case, beware, the company may be existing on a hand-to-mouth basis. A company is more likely to offer discount or cashback incentives for a finance deal since they know they will get their money up front. Not all customers who order double-glazing have the readies to pay for it on installation.

Any credit purchase has far more consumer protection than a simple cash transaction. Your deposit is protected, and with the more reputable companies, the bank may even back up their guarantees. This is not a benefit you will enjoy if you arrange your own finance. If you add the cost to your mortgage you will probably pay more in the long run. On the down side, the APR is likely to be uncompetetive. You must balance this against the discounts and incentives you may receive. The bottom line is what will the total cost be compared to paying the balance by cheque. Flexibility is also very important. Can you set your own level of payments and vary them? Can you pay lump sums and make an early redemption without penalty? Do spend some time on this.
How Much?
A good salesman from a reputable company should always work from a price list. Of course, no one in their right mind ever pays the full list price, as there are always discounts available. Some of these discounts may be conditional. The salesman should explain all the discounts and the conditions attached in order to reach the final price.

Be aware that if you push for further discounts in order to get a better bargain, you could be shooting yourself in the foot. Every company has to make a profit to pay to run their business. The gross profit margin is often 40% of their basic cost to do the job. If a company says that the replacement window cost is normally £1,000 but because there's a 'special offer' at the moment giving 50% off, this means that the salesman will sell you the job at £500. It should be costing around £600 just to do the job, if the £1,000 retail price is to be believed, so the company will actually be making a £100 loss on your job. Either the salesman is telling you lies or the company will soon be out of business.

Another point to consider is that if a company is capable of producing windows of varying quality, you will have been shown the top quality windows priced accordingly, but may end up with budget quality actually fitted.

Of course you should not pay more than you can afford for your windows, but it is an even bigger mistake to pay too little. Your home is the biggest investment you are ever likely to make and the windows are an integral part of it. From the point of view of strength, security, insulation and maintenance, you should consider paying the most you can afford for the best quality. Unlike other purchases that you can exchange, sell or write off if you make a mistake, double glazing units should be regarded as a once-only purchase.

Steel yourself, here comes the close.
Hopefully, armed with this information you will feel better prepared to consider the relative merits or otherwise of the company and their products. You will then be more confident of your own opinion instead of being swayed by the irresistible deal-closing patter of the salesman who, unlike you, is a professional. Expect to be offered a special ‘tonight only’ price. Of course it makes much better business for the company if the salesman can wrap it up in one appointment, but you can rest assured that if you call back in a few days time and request that ‘tonight only’ offer, you will not be turned down.

However, there is nothing wrong with doing a deal on the night provided that you are doing it for the right reasons. If these are the windows you actually want above all others, if this company is one you can trust, and if the price is right, then why not?

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Comments on this review

  • Lini_M published 24/01/2008
    excellent review - a lot of very informative advice! thanks :)
  • fluffy20 published 26/05/2006
    Very helpful as we are about to move house and renovate an old one. I was interested in the bit where the sales rep arrives and measures the windows. Last time we went through this charade 2 out of 3 reps did not even have a tape measure with them yet were able to give a quote. The one who did measure up first got the job. Jo
  • megaroons published 27/02/2006
    First class review. I have printed it out, we have a rep. coming any minute now!
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