Ten Things To Look For In Good Quality Windows

Metal reinforcement inside uPVC windows should always be included in the vertical sections of the frame. However, profile extruders and window fabricators will have their own recommended specifications for reinforcement of their own products.

The larger the window, the more important internal reinforcement is, in order to support your uPVC windows and reduce any movement.  Having said that, reinforcing very small uPVC windows has little effect on durability and performance.

Dark coloured frames such as woodgrain effect uPVC windows should always be fully reinforced as the darker material can expand and contract at up to four times the rate of white uPVC windows. The internal reinforcement is designed to reduce this.

Ten Things To Look For In Good Quality Windows

Traditionally, when glass was installed in wooden windows, it would be held in place with either putty or a wooden bead nailed into place on the outside of the frame. Early uPVC windows also had external beads to hold the insulating glass sealed units within their frames.

And because the glazing beads were on the outside of the window they were easily removable by burglars, who would simply take out the bead, lift the sealed unit out and climb through the opening.

Products such as double sided tape to hold sealed units into place are often used to improve security in externally beaded frames but ask yourself, if a sealed unit was broken and the installer returned to replace it, would he remove the unit from the outside? Yes?….then so can a burglar.

Modern uPVC windows should all be internally beaded which means that the glass sealed units are installed from inside and can therefore only be removed from the inside. Burglars do not like to invite attention with the noise of breaking glass, so homes with internally glazed uPVC windows are less likely to be successfully burgled than those with externally glazed uPVC windows.

Externally beaded uPVC windows are cheaper to manufacture

The only valid reason for an installer supplying externally beaded windows these days is that are cheaper to manufacture. Internally glazed uPVC windows go through a manufacturing process known as reverse butt welding which is more time consuming and therefore more expensive than manufacturing externally glazed windows.

Ten Things To Look For In Good Quality Windows

There are six recognised shades of white within the uPVC window industry. They range from brilliant white to an off-white almost cream shade of white.

It is important that where trims are used around a window or door, the same colour white is used for the frames and the uPVC architraves, D-moulds and quadrants.

The problem is multiplied when conservatories are erected with a different shade of white uPVC used for the windows and doors, compared to the roof spars, gutters and trims.

Generally speaking, from our experience bright white uPVC replacement windows look better than off-white ones, which after a while can look as they have faded.

Ten Things To Look For In Good Quality Windows

No-one would consider single glazed PVCu replacement windows and doors these days, in fact it would be in breach of Building Regulations to install them in residential properties now.

The term double glazing originates from the introduction of insulating glass sealed units formed from two sheets of glass, separated by a spacer bar around the edge. The glass unit is then sealed to prevent air from getting in from outside as this would bring in water vapour which can give rise to condensation between the two sheets of glass.

The width of sealed units in uPVC windows

Generally speaking, the wider the gap between the two sheets of glass, the better the insulating properties of the sealed unit are (though exceptionally wide sealed units can encourage convection within the unit, which reduces its effectiveness).

Common consensus within the replacement window industry is that a 28 mm sealed unit (normally consisting of two sheets of 4 mm glass and a 20 mm spacer bar) is the most efficient combination. Sealed units which are narrower than 28 mm are only normally used by installers to save money, or because narrow PVCu or aluminium frames won’t take a 28 mm unit.

Triple Glazing

Advancements in window technology, particularly in Scandinavia, have involved triple glazing but the benefits for use given the climate in the United Kingdom often do not justify the extra cost.

Another issue with triple glazing is that the extra weight of the glass in each opening sash means that the overall size of sashes needs to be reduced, which could compromise the use of an opening window as an effective fire escape.

Warm edge spacer bars in sealed units

The spacer bar between the two sheets of glass is traditionally extruded aluminium with a silicone desiccant inside (to absorb any water vapour which happens to be in the air inside the factory at the time of manufacture).

Aluminium though, is a good conductor of heat – and cold – and is therefore inefficient at preventing heat loss around the edge of the sealed unit.

A warm edge, or thermal break spacer reduces the heat lost around the perimeter of a sealed unit and some types can provide almost 1,000 times more thermal insulation than aluminium spacer bars, thus improving energy efficiency. With an aluminium spacer bar, the edge of the inner pane of glass within a sealed unit can be quite cold, which can result in condensation around its perimeter; this is vastly reduced by using a warm edge spacer bar.

Ten Things To Look For In Good Quality Windows

Over 25% of the heat in your home escapes through windows and doors, so energy efficient uPVC windows not only keep your home warm, they are also good for the environment.

The Government’s commitment to reducing energy emissions combined with the potentially harmful effects of global warming are central to new legislation requiring that uPVC windows meet minimum standards of energy efficiency.

Window Energy Ratings are based on a scale of A to G in exactly the same way that household appliances such as refrigerators are rated – A being the most efficient, G being the least efficient.

uPVC windows in domestic properties must now achieve a minimum of a C rating to satisfy current Building Regulations.  An ‘A’ rating can only generally be achieved for a window when it includes an insulating glass sealed unit which includes low e glass, argon and a warm edge spacer.

Window Energy Ratings take into account the following factors: –

• The effectiveness of PVCu replacement windows in preventing heat loss from your home.

• The amount of light and heat a window allows in from the sun, known as solar heat transmission or solar heat gain.

• Air leakage through the seals of a window.

• The proportion of the total window taken up by the frame.

Ten Things To Look For In Good Quality Windows