A guide explaining everything that's involved with replacing a blown window. If you're window has become foggy and filled with condensation then its likely that the seal has blown and will need to be replaced.
A blown window is a term used when a gap is present between the panels of a double-glazed window. This gap allows moisture to enter the space between each panel and causes constant obscurities such as fogging and condensation that cannot be wiped away.
In many cases where a window has blown, you may be able to feel the presence of a draught, where air is entering through the gap. Instead of replacing the entire window, it is often possible to simply replace the misted double-glazing unit. The process can be effectively carried out by any window fitter or local joiner.
It is important to replace a blown window from the moment you recognise the problem. If left unattended, the double-glazed window will not be performing as it should. Cold air will enter the property with ease, along with heat quickly escaping. This means that the energy efficiency of your home will be jeopardised.
You may experience signs of damp and condensation occurring, as moisture will also enter through the faulty window. Generally, replacing a blown double-glazed window is something that should be left to a professional. This ensures that you receive the best quality replacement and your window performs correctly.
On average, the cost of a replacement double glazed unit costs around £100-£300, depending on your style of glass. There are many different types of glass panels available, with Sash, Georgian and Stained Glass being the costliest. The size of your window unit will also determine the replacement cost. A large, multi-bay window can cost significantly more to repair than a standard or smaller style window.
You will also need to consider that a professional window fitter or joiner will likely charge an additional labour charge which can significantly impact the cost of a window replacement. Typically, the charge for a professional window fitters labour will range between £100-£250 per day.
The table below demonstrates how these cost affecting factors can impact the cost of replacing a blown window. Please note, the prices below are estimates and should be used as a guide only.
|Standard Double-Glazed Window
|1 Hour or Less
|Large Double-Glazed Window
|1 – 2 Hours
|Small Sash Window
|Large Sash Window
|1 – 2 Hours
|Large Multi-Bay Window
|2 – 3 Hours
The first step when replacing a blown window is to thoroughly assess the problem. A professional window fitter will examine your window for signs of damage to determine the best solution for you. In some cases, it may be possible to simply replace the blown double-glazing panel.
However, depending on the extent of the damage and the age of the window, you may decide it would be better to replace the entire unit.
Once you have decided on a solution, the window fitter will begin measuring the glass or the unit in order to source the materials. The fitter may also discuss with you the various types of glass that are available, such as toughened glass or tinted glass.
Many people tend to choose a glass that best resembles any other windows or doors on the property, but you should be aware of the options that are available to you.
On the day of the installation, your window fitter will begin by carefully removing the existing or damaged panes of glass. This typically involves taking off the beads from both sides of the window along with the top.
These beads are what secures the glass inside the unit of the window, so it is important to remove these before attempting to remove the glass. The area must then be clear of any dirt or debris, to ensure that the space is clean ready for the installation. Your fitter will proceed by positioning the new glass panel in place, ensuring that it is level and perfectly situated.
Finally, the beads can be re-installed and clicked in to place to support the new glass panel. The window fitter will conduct a final check to make sure that everything is perfect and that no air or moisture can enter between the glass of your window.
It may be possible for you to replace a double-glazing window panel yourself, providing that you do not need to replace the entire window unit. While replacing a glass panel is usually a straightforward process, we always advise you seek the assistance of a professional window fitter to carry out the job for you.
Attempting a DIY window replacement does not always mean that you will save time or money, in fact, a professional would be able to install the new glass in much less time. You would however save money on the cost of a professional’s labour, although you should consider that you are going to need the correct tools and equipment to carry out the work.
Before attempting any DIY home improvement project, you should consider the potential problems and pitfalls first. While you may believe that you will save time and money by carrying out the work yourself, this is not often the case. If you are inexperienced or unfamiliar with the process, you risk causing further damage to your property or the window frames which can be very costly to replace. Not only that, but it is essential that the replacement panel is installed correctly.
Failure to do so can result in the initial problem re-occurring, and you needing to resolve the issue all over again. Improper fitted windows can lead to a great deal of issues, such as leaks, noise pollution and poor insulation. For best results, we always advise you seek the services of an experienced professional.
Here is a list of commonly asked questions regarding replacing blown windows.
The most recognisable sign of a blown window will be the presence of constant fogging or misting that cannot be wiped away. This is due to the condensation and moisture harbouring between the panels. You may experience other signs such as draughts and increased energy bills.
On the day of the installation, a blown window can usually be replaced in less than an hour. Although this will depend on the scale and complexity of the job.
The only way to remove the moisture between double glazed panels is by replacing the damaged or blown window itself. This requires drying out the moisture that has accessed the space between the glass panels.
It may be possible for you to carry out a simple replacement yourself. However, for best results you should contact a professional window fitter. Poorly fitted windows can result in further issues establishing.
Over time, windows tend to expand and contract due to the effects of weathering and use. This causes wear and tear that naturally leads to a reduction in the windows performance. Blown windows are one of the most common issues faced with double or triple-glazed units.
The average lifetime for a double-glazed window is expected to last between 20-25 years. This will vary depending on your location and the quality of the unit.