Sash Window Double Glazing
Replacing Single Glazing with Double Glazing
Traditionally, the structure of the sash window has not allowed the fitting of double glazing while retaining the original historic appearance of the sash window detail. The double-glazed units were simply too thick.
But in the last decade or so different types of double glazing have come to the market.
One of these include slimline double-glazed units with a 7mm-wide spacer bar around the edges of the pane. This enables us to putty glaze the slim doubleglazed units into traditional sashes, replacing single glazing (but to mention, the glazing bars have to be at least 24mm in wide, if the width is less than that, the black seal between the two glass panes will be visible and visually unacceptable.
The narrow gap between the panes in these units can have a Krypton / Argon gas or similar in the slightly wider units or a Vacuum (in the narrowest of units). This new type of slimline double-glazed units allow us to successfully accommodate traditionally detailed sash windows.
When double glazing your sash windows we ensure glazing bars are exact match of original bars, glazing bars and external glazing bones are not stuck on instead housed into the sash in a lattice frame, and double-glazed sash windows are putty glazed on the outside.
As your Sliding Sash Window Refurbishment Experts, we can assist by installing slimline double-glazed units to your beautiful traditional sash windows.
Why Do I Need Double Glazing?
Often one of the issues with older sash windows in period properties, which are very important to preserve in a condition as close to the original as possible, are cold air draughts and heat leakage through the windows. While owners generally assume they need to replace the glazing or install double glazing, in reality the air gaps between sashes and the frame are the main issue, whether from simple wear over time or from improper sealing of the windows at some stage during their lifetime.
It is worth mentioning that, if a sash window has not been draught proofed, there would be very little benefit in double glazing it, as the heat loss from an unrefurbished sash window is mostly due to draughts of about 80%, while the single glass pane is only responsible for about 20% of the total heat loss. So before considering to fit double glazing to your sash windows you should talk to us first and let RepairSashWindows.ie to advise you which option is more economical, should you to draught proof only or fit double glazing, or both at the same.
Thermal Performance and Sound Reduction
Thermal performance of double glazed units is measured in U-Values – the lower the value: the better the performance. Single glazing has a U-Value of about 5.4, while the regulation for double glazing requires it to be 1.9 or lower.
All our double glazed units come with energy efficient A-rated glass units and with warm edge spacer bar which is made from an insulated composite plastic material. This spacer bar also helps improve the energy efficiency of the overall window.
Where noise is a problem, our unique combination of double glazed and draught proofed sash windows will not only reduce heat loss but will reduce noise pollution as well.
Condensation
Apart from keeping heat in and noise out, double glazing has another major benefit, it prevents condensation on the glass in cold weather. Single glazed sash windows are a primary cause of condensation as they have a cooler inside surface temperature than double glazed windows and the only thing separating your home from the cold outside environment is one pane of glass.
Condensation accumulates on single glazing in rooms where warm moist air hits the cold glass. It condenses on the glass, forming pools of water at the bottom of the panes. When double glazed unit U-values are 1.9 or lower, condensation is normally prevented, when the moisture levels in the air are not extreme. And if moisture accumulation on the inside of glass is not prevented it can lead to the growth of black mould, corrosion of fittings as well as damage to woodwork and the paint finish on a window.
Double Glazing for Sash Windows in Listed Buildings
Historic period timber sash windows are normally unable to accommodate double glazed units, and many planning authorities object to double glazing being installed in listed buildings and sensitive conservation areas in Dublin and other parts in Ireland.
Slimline double glazing is a viable alternative that is accepted by conservation officers in many cases. RepairSashWindows.ie supply and install Slimline double glazed units, designed to fit existing timber sash windows. By using a smaller, gas-filled gap between the glass panes, slimline double glazed units can achieve an energy rating on par with standard double glazing. This makes them perfect for heritage buildings and period homes in Ireland which need both the thermal benefits of energy efficiency and an authentic period appearance.
We work closely with a number of local authorities and conservation officers to find the best solution for every property. If slimline double glazing is not approved, we can offer single glazing or secondary glazing.
If there is historic glass in the sash window, the Conservation Officers normally refuse to issue a permission to change the glass or install double glazing.
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