Certifications and Double Glazing

Double glazing has been around since at least the 1970s, and most homes, barring perhaps period properties, now have it. As a homeowner, you might not know exactly when the windows were installed, or who by, and this may make it difficult to know if they arestill in warranty and when they might need replacing.

Unfortunately, there is no universal way to check this sort of information, especially with older windows. There are however, a few good tips that might help you. I’m going to assume that you have already checked all your documentation and paperwork that you may have received from the previous owner!


If your windows were installed after April 2002, then your windows should have been registered with FENSA. FENSA is a national scheme designed to ensure that replacement windows meet building regulation requirements, without having to go through the time consuming process of approval from the planning department. Building regulations now stipulate that all replacement windows must meet minimum requirements, and be issued with a certificate to confirm this.

What does that mean for you? It means that if the windows were installed after this time, the previous owner should have passed the FENSA certificate on to you. Of course, this doesn’t always happen! If the windows were DIY’d or done by a non-FENSA company, then the windows should have had full local authority Building Control Approval. This is easy to check – your local council will have a database that is readily accessible online.

You can also check the FENSA website, which holds a database of all past certificates, and even re-order your certificate there. So if the works have been done in the last 15 years or so, you should be able to find all the information you need – like the manufacturer, installer and age of the glazing.

Is my Warranty Transferable?

So you have bought a home and got your FENSA certificate – how do you know that the warranty is transferable? All FENSA registered installers must offer a transferable warranty – there are no exceptions to this, so you should go directly to FENSA if you are having a hard time getting your installer to honour the warranty.

Older Double Glazing

If your windows don’t show up on any of these checks, chances are that they were installed prior to 2002. This will make finding the installer a lot more difficult, but you can probably be sure that they are no longer in warranty.

As for replacing the windows, remember that the age at which windows need replacing can vary greatly depending on the type of window, the quality of them, and how well they were installed. Age actually doesn’t mean a great deal in this instance. A well installed double glazed unit may last for 20 or even 30 years, with just the most straight-forward upkeep and maintenance, whereas a poor quality unit may need replacing in 10 years. You will find that uPVC frames tend to discolour and lose their integrity a little quicker than wooden windows, whilst wooden windows will need more maintenance over the years.

So don’t despair if you don’t know where to go about your windows – if they are from the last 15 years, you should be able to find your certificate, and if not your windows are almost certain to be out of guarantee. Fairly straight forward!

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