Everest Frequently Asked Questions
What is secondary glazing?
Secondary glazing is a glazed panel in a frame that is installed to the inside of your existing window. There are different types of secondary glazing, ranging from a DIY plastic-glazed frame that can be clipped to the inside of a window. Or, a glazed unit that is professionally installed.
The gap created between a window and the secondary glazing creates a thermal barrier that has two main benefits. The gap helps the window to reduce heat loss, which is a huge benefit for period properties that struggle to increase their energy efficiency. The gap is also effective at reducing external noise and can be more effective than specialist noise reduction glass.
Secondary glazing is designed to be barely noticeable. Everest units have a slim white aluminium frame fitted inside the window reveal, sitting discreetly behind your existing window, and from outside the property the original window is all you see. The glass is fully glazed for clarity rather than the hazy plastic used in cheap clip-in units, and there are four styles to match how your window opens.
Does secondary glazing stop condensation?
Secondary glazing reduces condensation on the original window rather than stopping it completely. The inner panel keeps moist room air away from the cold original glass, which is where condensation forms. It cannot fix the underlying humidity, so it works best alongside good ventilation and controlling moisture at its source, from cooking, showering and drying clothes indoors.
Does secondary glazing reduce noise?
Yes, and it outperforms double glazing for noise. Secondary glazing reduces noise because of the gap between the two windows panes which helps to reduce the resonation on the panes of glass and the reduction of sound energy across the gap. The air tightness of the frame also contributes to reducing sound leakage.
A standard double glazed window will reduce sound by up to 33dB. According to Historic England, a secondary unit with an air gap of 100mm or more can achieve sound insulation of up to 45dB.
Does secondary glazing work?
Yes. Secondary glazing is an energy efficient window solution that creates a large air gap between the original window and the room. It slows heat loss, cuts draughts and reduces noise. It is less expensive and less disruptive than replacing windows, and it is often the only option for listed buildings and conservation areas where the original windows have to stay. Everest units are made to measure with compression seals around the perimeter for an air tight fit.
Is secondary glazing as good as double glazing?
It depends what you need. For noise reduction, secondary glazing is better. For heat retention, modern double and triple glazing can perform better. Secondary glazing is the right choice when the original windows have to stay, in listed buildings and conservation areas.
Do I need listed building consent for secondary glazing?
Usually not. Secondary glazing can offer a perfect solution for listed buildings, as it does not damage or alter the original windows and is fitted inside the home. Also as it is easy to remove without damaging the fabric of the building, most planning authorities see it as an acceptable upgrade to a building. However, if you want to be certain it is always advisable to consult your local planning advisers.
How much does secondary glazing cost?
Everest secondary glazing costs from £500 per window, made to measure and professionally installed with a 10 year guarantee covering both the units and the installation. The price depends on the size of the window, the style of opening and the number of windows, and quotes can vary significantly due to the specific project and installation requirements.
