Double Glazing Buyers' Guide & Tips

Want to know what to expect when purchasing double glazing or conservatories in Suffolk and Essex? At Falcon Windows, we offer free advice. We genuinely like to give as much practical, double glazing advice as possible as we have built up a wealth of knowledge about products and installations over the years. We feel that we are well-placed to give honest, unbiased advice within our industry to any of our customers who are ready and willing to ask.

As a start, we have put together a double glazing buyers' guide to offer some intial help. Please click a topic below for further information.

Further hints and tips to help you are also available on the Cowboy Stoppers as well as Fensa Homeowner websites.

Click here to read a Which? article on "Double Glazing Sales Tactics Exposed".

At Falcon Windows we value our good name and reputation in the double glazing business. Please take time to watch our customer video testimonials or read their written comments about our approach, products, installation and workmanship. Thank you.


Ask your supplier if the windows you are having a quote for are mechanically fixed or fully welded. Mechanically are generally a cheaper option though they give the impression of a wooden window, whereas a fully welded window is much stronger.

If the costs that you have been quoted are similar, then go for the welded option. However, when you are having woodgrain, light oak or rosewood windows, mechanically jointed frames are aesthetically a better option as you don't see the criss-cross welds which you get with the welded frame.

Double glazing nowadays is far superior to what it used to be. New A+ Planitherm sealed units deliver a U value (insulation value) of 1.4, giving you better insulation. Even our standard sealed units achieve a window energy rating of WER A Rated. The U-value of the centre pane (glass only) is 1.219 W/m2K.The cavity is a 20 mm warm edge spacer bar and has an argon gas filling.The outer pane of glass is a Saint-Gobain Planitherm total + low emmisitivity glass.

With new windows nowadays you can experience condensation forming on the outside in the winter months. This is quite normal, as the heat from the house is not being able to get through to the outside. Although you will end up with condensation outside,this normally disperses by around 9 AM - 9:30 AM. Previously the old type double glazing used to let the heat out and in doing so it warmed up the outer pane, so it didn't allow any condensation to form. If you have new windows installed, you will find a significant difference and will probably find yourself turning your heating down.

Most companies will ask for a 10% deposit. This is quite normal.

At Falcon Windows Ltd we also take a 10% deposit with a signed contract. We only require final payment once the job is completed to your complete satisfaction.

Ask your supplier how long it will be before your windows /doors are installed. It is a good idea to get a firm date and have it confirmed in a contract.

At Falcon Windows we give rough dates initially and then confirm installation dates only when we have received all our customer's products and materials. Normally the time between order and installation is somewhere between 6-8 weeks

It is important to consider style and appearance when choosing your windows and doors, especially in the context of the properties around you or in your surrounding area. Even though you may think a certain design would look good on your house, it may not fit in with other properties in your street. (No one wants to stand out like a sore thumb!).

It's a good idea to look at similar properties in your area, get a feel for what designs there are and keep to a similar, style otherwise this could devalue your property.

Whilst some salesman like to keep their quotations down by skimping on openings and extras, you may leave yourself with simple designs and ones that can be unpractical. Your new windows need to be aesthetically pleasing and keep in a similar style to surrounding properties.

Always as your supplier about what guarantees they offer. This is most important.

Many companies offer an insurance backed guarantee, but they may not later seem as good as the salesman depicted. Some insurance backed guarantees only come into force 90 days after a company has gone into liquidation, which to most people is not much use - especially if they can't lock their front door or shut a window.

Do check whether the guarantee is for ten years as some only cover for five years.

At Falcon Windows Limited, we are proud to say we offer our own 10 year warranty, accompanied by a totally separate, quality insurance backed guarantee with Installations Assured Ltd (01234) 855377

Try to view previous installations by the company which you intend to go with and try, if possible, to ask their customers what they thought about them and their service.

Ask probing questions such as: Were they on time? Were they clean, tidy and polite? Had they respect for your property during the installation?

Falcon Windows are always pleased to share customer feedback. On our TESTIMONIALS page you can view all the testimonials in written and video form from our previous customers.

Ask to see a showroom, if the company has one, to see the product in situ and see how it functions. However if it's a very large showroom, just bear in mind that this usually comes at a cost, to you the customer!

Ask how the company which you intend to have fit your windows, about their fitters - are they self employed or employed by the company? If they are employed, they are not perhaps so much in a hurry to get the job done as would be a self-employed subcontractor.

A number of companies pay their fitters so much per window and so much per door etc, so fitters endeavour to install as much as possible in as short space of time - so corners may be cut!

Employed staff are not normally on an incentive to finish quickly, as they tend to be on a day rate, thus a more thorough job may be done. On the other hand, self-employed fitters may rely on regular work for their livelihood and many choose to work for highly regarded window companies to keep them earning.

Finally, many window fitters who work for national companies often approach smaller local firms, as they prefer to work for them as there's much less travelling involved and they get treated better and everybody works as a team.

The term noise is derived from Latin, meaning nausea and is used to describe sounds which are perceived as harmful or disturbing. The effects on health include difficulties concentrating and sleeping, raised blood pressure nervous disorders and even depression. Consequently double glazing does provide some sound proofing, especially where one pane of glass is thicker than the other eg. 6.4mm laminated one side (normally outside) and 4mm the other. This acts as a better sound barrier than normal sealed units and also is much more secure as burglars cannot penetrate laminated glass as it has 0.4mm perspex between the two 3mm panes of glass.

The best type of sound-proofing is secondary glazing as the gap between both panels is far greater, thus many households around airports have been fitted with secondary glazing to help with noise reduction. If you live on a main road with traffic noise, this can be a way of reducing further noise. Especially if you are in a listed building or live in a conservation area, it is generally the only option available, if you require to keep the window seat you have already installed either or avoid replacing them like-for-like which can be expensive.

Planning permission is sometimes required to fit replacement windows, especially if they are to be installed into a listed building or a conservation area. As well as this, if you are converting a loft with a velux window or converting a flat window to a bow or bay window, you will normally require planning permission from your local council.

It is advisable to ask for a quotation from three or four companies for your requirements as there can be a wide range in their quotations.

Falcon Windows have been in the trade for many years and the quotations which customers receive in for a job, in general always amaze us as they vary so much between one company and another for much the same thing.

Window companies you may think are more expensive are sometimes the most competitive and vice versa.

Never rush into signing a contract on the night as this is normally a ploy to get you locked in! Many salesmen are often around customers' houses for hours on end, trying for a sale as they are normally only on commission. If you sign up with some companies and decide to cancel, you can up to seven days, but after this it can be a headache to cancel and you can be sent threatening letters.

We at Falcon Windows Limited will only come to you if asked and by appointment only. We find out your requirements, measure up and then send a written quotation in the post within a matter of days. If the customer is interested, it is up him /her to contact us with a view to proceeding with the work.

It is part of our policy not to hound or put pressure on customers that we have sent quotations out to like some companies do, most people buy off someone that they can relate to and trust so long as the price is right and they are happy with the product.

Check on the locking mechanisms on the windows as most are of an espagnotte/shoot bolt type which is a mushroom-headed device which interlocks into a metal keep in the window frame along with shoot bolts top and bottom. This is a very secure locking mechanism that is used by most companies nowadays.

The Falcon Windows team recently replaced a window for a gentleman where he had a double-glazed window in his dining room. Unfortunately for him, he had been burgled and the burglers had crow-barred the sash window away from the frame because it was of the espagnotte locking mechanism only. This clearly shows that it pays to have an up-to-date locking mechanism installed to prevent this happening.

At Falcon Windows we can also offer security hinges and metal male and female interlocking sections on the hinge side of any opening window which gives added security.

Ask your supplier if they make good around the window with sealant or plastic trims. With respect most companies nowadays finish off with trims inside and out, but it's worth checking with the company, as trims look better by far and they don't fade like silicone does over time. Some customers just prefer cork finish on the insides which is fine, but the majority prefer a small trim section especially when there's wallpaper involved as this gives a neat clean finish.

We at Falcon Windows offer our customers different ways of finishing off our windows, but generally speaking our standard way of finishing is accepted by the majority of our customers. Externally it's normally plastic trimmed between the brickwork and window, however if it's a pebbledash finish, then it's normally sealed between the window and the pebbledash.

All windows and doors require the lubrication of all moving parts every three months, as this keeps them in tip-top condition and reduces service calls.

The frames will also require the occasional clean with a rag. Cotton sheeting is best for cleaning, especially when used with a special PVC-u solvent cleaner which can be bought from most supermarkets or wholesalers.

Ask your supplier if their windows are internally or externally beaded as this is a definite factor if safety is at the top of your priority list.

With some externally beaded window systems, you can gain entry by removing the bead with a sharp putty knife and removing the glass from the frame. With respect a lot of companies who have externally beaded frames glaze their sealed units onto a double-sided security tape which does not allow the sealed unit to be taken out unless you gain entry inside.

At Falcon Windows Limited,we along with many other companies install an internally beaded window which makes it nearly impossible to remove any glass to gain entry. Also we have a hidden external gasket which gives a better sight-line to the window. There is nothing worse than seeing a thick black gasket around a white window. Some windows come with white gaskets, but we would strongly recommend not to go with these, as after a few years from inside you may start to see green mould developing on the inside of the outer beading. When new, the windows look very nice as they give the impression of a wooden window, but the salesman never warns about the possible discolouration of these gaskets. With black gaskets there is no problem and the window looks the same after 10 years.

When designing replacement doors or windows the addition of glass options such as 'Georgian Grill' or 'Leaded Lights' can have one of the best impacts on the overall look.

Georgian Designs are usually made up by a white plastic profile inserted to make a design within the sealed unit. Lead light designs use lead in varying widths, applied to the glass to make rectangular, diamond 'panes'. There are also other heritage designs eg.Tudor.

Most Georgian designs are made with the use of aluminium alloy of varying widths (19 mm & 25 mm are the most common) 'pieced' together with 'crucifix' joiners to create the design.

You decide on the number of squares or rectangles you require and then divide the glass / window design accordingly. Be aware that it's usually not possible to have all the rectangles/squares equal in size. (Unless, of course, you start from scratch and resize the windows)

In practice this isn't usually a difficulty for most people - however one way to maybe decrease the effect of having varying sizes within the design is to consider having an 'equal sight line' design. With this equal sight lines design, even the parts of the window which do not open have 'dummy sashes' inserted. This has the effect of making the overall sizes of the different pieces of glass more alike.

Another is using aluminium extrusions within the sealed units can be used to create other designs in the windows. There are Gothic Arches or Georgian Arches. (The extrusion is bent in a curve for this.)

The most common lead light designs are square or rectangular and diamond shape designs. Other alternatives such as Elizabethan and Tudor designs are also available.

If you want to add a leaded design to an already existing window, strips of lead can be purchased from most DIY stores and this can be applied by yourself. (Varying widths available - 6 mm and 9 mm are most common). However this does require a 'steady' hand and a great deal of patience! The process is often referred to as 'single leading' because you can only apply the lead to one face of the glass - i.e. not the side of the glass facing that is towards the inside of the sealed unit.

Whilst the above can be rather satisfactory, it will never look as nice as 'double leading - this is where the lead is applied to both sides of the outside piece of the glass in a double-glazed unit prior to assembly.'

Condensation is an extremely underestimated cause of damage to our homes. It is responsible for rot in rafters, joists and wooden window frames; it can cause mould and fungal growth on walls and ceilings and if not dealt with, can damage our health.

Air in the home is actually a mixture of air and invisible water vapour. The average family produces 10 to 50 litres of moisture a day from activities like cooking, bathing, washing dishes, and doing laundry. Condensation is the conversion of the water vapour into a liquid and usually happens when the vapour cools. All air contains water vapour. The quantity contained depends on the temperature of the air. This ratio is called the relative humidity. Hot air is able to carry much more moisture than cold air, so as the temperature of air rises, in broad terms, it expands and attracts a greater volume of vapour. The temperature at which the vapour begins to condense is called the dew point. Condensation occurs whenever warm, moist air comes in contact with a surface or object cold enough to chill the moisture in the air below its dew point.

Outside, if this happens near the ground to a small layer of air, dew or frost will be formed, if a larger amount of air is involved, mist or fog will arise. If this happens to air that is rising in the atmosphere and expanding clouds will form

If it happens in the home....It's called condensation

As soon as warm air, containing vapour, hits a cooler surface, it will condense. This is most obvious on windows and wall tiles, but it is happening on the walls and ceilings a lot of the time. The common assumption is that if we insulate ourselves and warm the house thoroughly, then this should not happen...But it will, the air temperature will rise until it finds a cooler surface unless we let that air out and some cooler air in, which brings us on to ventilation.

Ventilation is the answer to condensation. There are many ways we can deal with symptoms or effects of condensation, but only one way to deal with the cause. We must ensure the home is adequately ventilated.

Ways to combat condensation

Wipe down walls and other surfaces regularly

While drying clothes indoors, ventilate the room

When people come in with wet coats, hang them outside to dry

Keep the kitchen door closed when cooking, and open the windows

After a bath or shower, try to ventilate the room to the outside, not to the rest of the house - just opening a window (and closing the door) will help.

Open all windows at least once a day. Change all of the air in the house as this becomes stale air and fresh air will help to

If security permits, leave top windows in the bedrooms open, especially at night, when the outside temperature drops and the indoor temperature rises as the heating kicks in. Breathing is a major contributor to condensation!

Reduce the number of indoor house plants, as plants increase humidity levels

If condensation is excessive, try a dehumidifier to remove excess humidity from the air

What causes condensation on windows?

Whenever there is excess humidity in the home, it will manifest itself on the coldest area of a wall, which is normally the window. The warmer the air, the more moisture it will retain, so when it comes in contact with the colder glass surface and the air is subsequently cooled, moisture is released in the form of condensation.

Do windows cause condensation?

No, condensation on windows is not the fault of the window, unless the window seal has failed and the moisture is in between the two sheets of glass. However, by replacing drafty windows or even installing a new roof, you are reducing air flow in your home and making it tighter. Tighter homes retain more humidity.

Windows present a difficult problem and years ago there used to be only one practical means of dealing with the traditional single glazed domestic window. This usually took the form of collecting the water forming in a channel at the bottom of the window and leading it via 'weep holes' to the external face. These 'weep-holes' or condensation outlets are small holes about 1/4" in diameter drilled at an angle through the frame so that water will pass by normal gravitation to the outside.

The easy answer these days to alleviate window condensation is with B rated sealed unit double-glazing into PVC-U frames. The insulation properties of both framework and glass is improving all the time as technology moves on, and as measures are introduced by government to improve energy efficiency in line with the Kyoto Protocol.

With double glazing, houses have become more effectively sealed, keeping any moisture produced within the house and providing better conditions for condensation to occur, therefore ventilation has become very important.

It is unlikely that a home in the UK can be condensation free; however by keeping your property properly maintained, and having warm edged argon filled B rated sealed units installed you should be able to almost eliminate condensation.