Using the wrong window film to keep your home warm can crack your glass, according to an expert. Tomass Kundzins, window film expert at Glacier Tinting, said some films absorb more solar energy than others, which can change how the glass heats up when sunlight hits it. If the film isn't suitable for that particular window, it can increase the risk of the glass cracking.
Why cheap film can cause damage
Thermal stress occurs when different parts of a pane of glass heat up or cool down at different rates. If you have solar controlled film on your windows, it increases the heat absorption. If the temperature difference is high enough, it can cause the glass to crack.
Kundzins said: "That doesn't mean fitting window film is dangerous, it just means the right film needs to be matched to the right glass." The tempting thing is to order cheap film that will keep you warm without breaking the bank, but if you haven't done your research properly, you can cause thermal stress to your glass.
Check your windows before buying
Kundzins explained: "Two windows can look almost identical, but that doesn't mean they have the same glass specification. One might have a coating or be made from a different type of glass, and that can affect which films are suitable."
"Make sure you find out what you've actually got before ordering anything. If you're not sure, ask the window manufacturer or a professional film installer to check."
The first thing to check is whether your windows are single, double or triple glazed, and see if they have any existing coatings. Read the manufacturer's compatibility guidance on any window film you buy, because some products are only suitable for particular kinds of glazing types.
Kundzins added: "Be wary of buying film purely because it's cheap or has good reviews. A film might work perfectly well on one person's windows and be completely unsuitable for somebody else's." He also advised checking whether applying the film could affect any existing glazing warranty, particularly if your windows are relatively new.
